β-arrestin2 recruitment by β-adrenergic receptor agonists and antagonists / 生理学报

A large number of β-adrenergic receptor (β-AR) agonists and antagonists are widely used in the treatment of cardiovascular diseases and other diseases. Nonetheless, it remains unclear whether these commonly used β-AR drugs can activate downstream β- arrestin-biased signaling pathways. The objective of this study was to investigate β-arrestin2 recruitment effects of β-AR agonists and antagonists that were commonly used in clinical practice. We used TANGO (transcriptional activation following arrestin translocation) assay to detect the β-arrestin2 recruitment by β-AR ligands in HEK293 cell line (HTLA cells) stably transfected with tetracycline transactivator protein (tTA) dependent luciferase reporter and β-arrestin2-TEV fusion gene. Upon activation of β-AR by a β-AR ligand, β-arrestin2 was recruited to the C terminus of the receptor, followed by cleavage of the G protein-coupled receptors (GPCRs) fusion protein at the TEV protease-cleavage site. The cleavage resulted in the release of tTA, which, after being transported to the nucleus, activated transcription of the luciferase reporter gene. The results showed that β-AR non-selective agonists epinephrine, noradrenaline and isoprenaline all promoted β-arrestin2 recruitment at β1-AR and β2-AR. β1-AR selective agonists dobutamine and denopamine both promoted β-arrestin2 recruitment at β1-AR. β2-AR selective agonists procaterol and salbutamol promoted β-arrestin2 recruitment at β2-AR. β-AR non-selective antagonists alprenolol and pindolol promoted β-arrestin2 recruitment at β1-AR. β1-AR selective antagonists celiprolol and bevantolol showed β-arrestin2 recruitment at β1-AR. β2-AR selective antagonists butoxamine showed β-arrestin2 recruitment at β1-AR. These results provide some clues for the potential action of β-AR drugs, and lay a foundation for the screening of β-arrestin-biased β-AR ligands.

Noradrenaline modulates the spontaneous firing activities of Purkinje cells via α2-adrenergic receptor in mouse cerebellar cortex / 生理学报

Cerebellar Purkinje cells (PCs) exhibit two types of discharge activities: simple spike (SS) and complex spike (CS). Previous studies found that noradrenaline (NA) can inhibit CS and bidirectionally regulate SS, but the enhancement of NA on SS is overwhelmed by the strong inhibition of excitatory molecular layer interneurons. However, the mechanism underlying the effect of NA on SS discharge frequency is not clear. Therefore, in the present study, we examined the mechanism underlying the increasing effect of NA on SS firing of PC in mouse cerebellar cortex in vivo and in cerebellar slice by cell-attached and whole-cell recording technique and pharmacological methods. GABAA receptor was blocked by 100 µmol/L picrotoxin in the whole process. In vivo results showed that NA significantly reduced the number of spikelets of spontaneous CS and enhanced the discharge frequency of SS, but did not affect the discharge frequency of CS. In vitro experiments showed that NA reduced the number of CS spikelets and after hyperpolarization potential (AHP) induced by electrical stimulation, and increased the discharge frequency of SS. NA also reduced the amplitude of excitatory postsynaptic current (EPSC) of parallel fiber (PF)-PC and significantly increased the paired-pulse ratio (PPR). Application of yohimbine, an antagonist of α2-adrenergic receptor (AR), completely eliminated the enhancing effect of NA on SS. The α2-AR agonist, UK14304, also increased the frequency of SS. The β-AR blocker, propranolol, did not affect the effects of NA on PC. These results suggest that in the absence of GABAA receptors, NA could attenuate the synaptic transmission of climbing fiber (CF)-PC via activating α2-AR, inhibit CS activity and reduce AHP, thus enhancing the SS discharge frequency of PC. This result suggests that NA neurons of locus coeruleus can finely regulate PC signal output by regulating CF-PC synaptic transmission.

Microcirculation improvement after short-term infusion of vasopressin in septic shock is dependent on noradrenaline

OBJECTIVES: To assess the impact of vasopressin on the microcirculation and to develop a predictive model to estimate the probability of microcirculatory recruitment in patients with septic shock. METHODS: This prospective interventional study included patients with septic shock receiving noradrenaline for less than 48 hours. We infused vasopressin at 0.04 U/min for one hour. Hemodynamic measurements, including sidestream dark-field imaging, were obtained immediately before vasopressin infusion, 1 hour after vasopressin infusion and 1 hour after vasopressin withdrawal. We defined patients with more than a 10% increase in total vascular density and perfused vascular density as responders. ClinicalTrials.gov: NCT02053675. RESULTS: Eighteen patients were included, and nine (50%) showed improved microcirculation after infusion of vasopressin. The noradrenaline dose was significantly reduced after vasopressin (p=0.001) and was higher both at baseline and during vasopressin infusion in the responders than in the non-responders. The strongest predictor for a favorable microcirculatory response was the dose of noradrenaline at baseline (OR=4.5; 95% CI: 1.2-17.0; p=0.027). For patients using a noradrenaline dose higher than 0.38 mcg/kg/min, the probability that microcirculatory perfusion would be improved with vasopressin was 53% (sensitivity 78%, specificity 77%). CONCLUSIONS: In patients with septic shock for no longer than 48 h, administration of vasopressin is likely to result in an improvement in microcirculation when the baseline noradrenaline dose is higher than 0.38 mcg/kg/min.

Effects of Continuous and Accumulated Exercise on Endothelial Function in Rat Aorta / Efeitos do Exercício Acumulado e Contínuo sobre a Função Endotelial em Aorta de Ratos

Abstract Background: The practice of exercise in short bouts repeated throughout the day may be an alternative strategy to lift people out of physical inactivity. Objective: to evaluate if accumulated exercise, as occurs in continuous exercise training, improve endothelial function in rat aorta. Methods: Wistar male rats were divided into three groups: continuous exercise (CEx, 1 hour on the treadmill) or accumulated exercise (AEx, 4 bouts of 15 minutes / day) for 5 days/week for 8 weeks, or sedentary (SED). During the training period, body weight gain and increase in exercise performance were recorded. On sacrifice day, aorta was dissected into rings (3-5 mm) and mounted on the organ bath. Results: Fitness was significantly greater in CEx and AEx rats as compared with SED animals. In addition, compared with the SED group, CEx animals had a lower body mass gain, and the aorta obtained from these animals had reduced contractile response to norepinephrine and greater acetylcholine-induced relaxation. These results were not observed in ACEx animals. Conclusions: Both CEx and AEx improved fitness, but only CEx led to reduced body weight gain and improved endothelial function.

Resumo Fundamento: A prática de exercícios em sessões curtas que se repetem ao longo do dia pode ser uma alternativa para tirar as pessoas da inatividade física. Objetivo: Verificar se o exercício acumulado, tal como ocorre com o treinamento com exercício contínuo, melhora a função endotelial na aorta de ratos. Métodos: Ratos Wistar machos foram divididos em 3 grupos: treinamento com exercício contínuo (ExC; 1 hora em esteira) ou com exercício acumulado (ExA; 4 sessões de 15 minutos ao longo do dia) por 5 dias/semana, durante 8 semanas, ou grupo sedentário (SED). Durante o treinamento, foram registrados o ganho de peso corporal e desempenho na esteira. No dia do sacrifício, anéis (3-5 mm) da aorta foram obtidos e montados em banho de órgãos. Resultados: Animais ExC e ExA mostraram aptidão física significativamente maior em comparação com os SED. Paralelamente, em comparação com SED, animais ExC tiveram menor ganho de massa corporal, e aortas retiradas desses animais mostraram respostas contrácteis à noradrenalina reduzidas e maior relaxamento induzido pela acetilcolina. Esses resultados não foram observados no grupo ExA. Conclusões: Tanto o ExC quanto o ExA melhoraram a aptidão física, mas somente o ExC foi capaz de reduzir o ganho de peso corporal dos animais e melhorar a função endotelial.

Migração e invasão do câncer de boca via ativação de receptor beta 2 adrenérgico por mediador do estresse / Cell migration and invasion of oral cancer via activation of beta 2 adrenergic receptor by stress mediator

A ativação do receptor beta 2 adrenérgico (β2-AR), pelos mediadores químicos do estresse, pode induzir efeitos estimuladores ou inibidores na migração e invasão celular, dependendo do tipo de tumor maligno. A importância deste receptor na evolução do câncer de boca não está totalmente esclarecida. O objetivo deste estudo foi verificar a expressão do β2-AR em linhagens de carcinomas espinocelular de boca (SCC-9 e SCC-25), e investigar o papel da ativação deste receptor pela norepinefrina e de seu bloqueio por um antagonista na migração e invasão destas células neoplásicas. As células SCC-9 e SCC-25 foram investigadas quanto à expressão gênica e proteica do β2-AR, respectivamente, pelo RT-qPCR e pelo Western blot. A migração e a invasão celular foram analisadas pelo ensaio de cicatrização de feridas e pelo sistema de câmeras de invasão Transwell, respectivamente. Diferentes concentrações (0,1; 1 e 10μM) de norepinefrina foram utilizadas para estimular e 1μM de propranolol foi empregado para bloquear os receptores beta adrenérgicos nas células neoplásicas. As diferenças das médias obtidas nos experimentos de invasão e migração de SCC-9 e SCC-25 e da expressão proteica do β2-AR, foram comparadas pelo teste t de Student com nível de significância de 5%. Os resultados mostraram que a expressão gênica e proteica do β2-AR foi verificada em ambas as linhagens de câncer de boca. A concentração de 10μM de norepinefrina inibiu, significativamente (p≤0,05), a migração e invasão celular de SCC-9 e SCC-25, sendo este efeito mais acentuado nas células SCC-25. Além disso, houve uma redução significativa (p≤0,05) do efeito da norepinefrina na migração celular quando os β2-AR foram inibidos pelo propranolol. Adicionalmente, o bloqueio dos β-ARs pelo propranolol reverteu parcialmente o efeito da norepinefrina na capacidade invasiva de SCC-9 e SCC-25. Estes resultados comprovam que a norepinefrina, via ativação do β2-AR, reduziu a migração e a invasão das...

The activation of beta 2 adrenergic receptor (β2-AR), by chemical mediators of stress, can induce stimulatory or inhibitory effects on cell migration and invasion, depending on the type of malignancy. The importance of this receptor in the oral cancer outcome is not fully understood. The aim of this study was to verify β2- AR expression in oral squamous cell carcinoma cell lines (SCC-9 and SCC-25), and to investigate the role of activation of this receptor by norepinephrine and its blockade by an antagonist in migration and invasion of these neoplastic cells. SCC-9 and SCC-25 cells were investigated for gene and protein expression of β2-AR, respectively, by RT-qPCR and Western blot. The cell migration and invasion were analyzed by wound healing assay and Transwell invasion camera system, respectively. Different concentrations (0.1, 1 and 10μM) of norepinephrine were used to stimulate and 1μM propranolol was used to block the beta adrenergic receptors on cancer cells. Differences in mean values of the invasion and migration assays of SCC-9 and SCC-25 and β2-AR protein expression were compared by the Student t test with 5% significance level. The results showed that β2-AR gene and protein expression was verified in both oral cancer cell lines. The concentration of 10μM of norepinephrine inhibited significantly (p≤0.05), cell migration and invasion of SCC-9 and SCC-25, being the most pronounced effect in SCC-25 cells. Furthermore, there was a significant reduction (p≤0.05) of norepinephrine effect on cell migration when the β2-AR was inhibited by propranolol. In addition, blockade of β-ARs by propranolol partially reversed the effect of norepinephrine on the invasiveness of SCC-9 and SCC-25. These results show that norepinephrine via β2-AR activation, reduced the migration and invasion of oral squamous cell carcinoma cells and, therefore, the use of beta-adrenergic receptors agonists could become an adjuvant therapeutic target in the treatment of this malignancy.

Migração e invasão do câncer de boca via ativação de receptor beta 2 adrenérgico por mediador do estresse / Cell migration and invasion of oral cancer via activation of beta 2 adrenergic receptor by stress mediator

A ativação do receptor beta 2 adrenérgico (β2-AR), pelos mediadores químicos do estresse, pode induzir efeitos estimuladores ou inibidores na migração e invasão celular, dependendo do tipo de tumor maligno. A importância deste receptor na evolução do câncer de boca não está totalmente esclarecida. O objetivo deste estudo foi verificar a expressão do β2-AR em linhagens de carcinomas espinocelular de boca (SCC-9 e SCC-25), e investigar o papel da ativação deste receptor pela norepinefrina e de seu bloqueio por um antagonista na migração e invasão destas células neoplásicas. As células SCC-9 e SCC-25 foram investigadas quanto à expressão gênica e proteica do β2-AR, respectivamente, pelo RT-qPCR e pelo Western blot. A migração e a invasão celular foram analisadas pelo ensaio de cicatrização de feridas e pelo sistema de câmeras de invasão Transwell, respectivamente. Diferentes concentrações (0,1; 1 e 10μM) de norepinefrina foram utilizadas para estimular e 1μM de propranolol foi empregado para bloquear os receptores beta adrenérgicos nas células neoplásicas. As diferenças das médias obtidas nos experimentos de invasão e migração de SCC-9 e SCC-25 e da expressão proteica do β2-AR, foram comparadas pelo teste t de Student com nível de significância de 5%. Os resultados mostraram que a expressão gênica e proteica do β2-AR foi verificada em ambas as linhagens de câncer de boca. A concentração de 10μM de norepinefrina inibiu, significativamente (p≤0,05), a migração e invasão celular de SCC-9 e SCC-25, sendo este efeito mais acentuado nas células SCC-25. Além disso, houve uma redução significativa (p≤0,05) do efeito da norepinefrina na migração celular quando os β2-AR foram inibidos pelo propranolol. Adicionalmente, o bloqueio dos β-ARs pelo propranolol reverteu parcialmente o efeito da norepinefrina na capacidade invasiva de SCC-9 e SCC-25. Estes resultados comprovam que a norepinefrina, via ativação do β2-AR, reduziu a migração e a invasão das...

The activation of beta 2 adrenergic receptor (β2-AR), by chemical mediators of stress, can induce stimulatory or inhibitory effects on cell migration and invasion, depending on the type of malignancy. The importance of this receptor in the oral cancer outcome is not fully understood. The aim of this study was to verify β2- AR expression in oral squamous cell carcinoma cell lines (SCC-9 and SCC-25), and to investigate the role of activation of this receptor by norepinephrine and its blockade by an antagonist in migration and invasion of these neoplastic cells. SCC-9 and SCC-25 cells were investigated for gene and protein expression of β2-AR, respectively, by RT-qPCR and Western blot. The cell migration and invasion were analyzed by wound healing assay and Transwell invasion camera system, respectively. Different concentrations (0.1, 1 and 10μM) of norepinephrine were used to stimulate and 1μM propranolol was used to block the beta adrenergic receptors on cancer cells. Differences in mean values of the invasion and migration assays of SCC-9 and SCC-25 and β2-AR protein expression were compared by the Student t test with 5% significance level. The results showed that β2-AR gene and protein expression was verified in both oral cancer cell lines. The concentration of 10μM of norepinephrine inhibited significantly (p≤0.05), cell migration and invasion of SCC-9 and SCC-25, being the most pronounced effect in SCC-25 cells. Furthermore, there was a significant reduction (p≤0.05) of norepinephrine effect on cell migration when the β2-AR was inhibited by propranolol. In addition, blockade of β-ARs by propranolol partially reversed the effect of norepinephrine on the invasiveness of SCC-9 and SCC-25. These results show that norepinephrine via β2-AR activation, reduced the migration and invasion of oral squamous cell carcinoma cells and, therefore, the use of beta-adrenergic receptors agonists could become an adjuvant therapeutic target in the treatment of this malignancy...

Norepinephrine infusion increases urine output in children under sedative and analgesic infusion / Infusão de noradrenalina aumenta o débito urinário de crianças recebendo drogas sedoanalgésicas

Objective: to evaluate the effects of early norepinephrine (NE) infusion in children submitted to mechanical ventilation (MV) requiring continuous sedative and analgesic infusion. Methods: double-blinded, randomized, placebo-controlled trial enrolling children (1 month to 12 years of age) admitted to a Brazilian PICU and expected to require MV and continuous sedative and analgesic drug infusions for at least five days. Children were randomized to receive either norepinephrine (NE) (0.15 mcg/kg/min) or normal saline infusion, started in the first 24 hours of MV, and maintained for 72 hours. We compared hemodynamic variables, fluid intake, renal function and urine output between groups. Results: forty children were equally allocated to the NE or placebo groups, with no differences in baseline characteristics, laboratorial findings, PRISM II score, length of MV, or mortality between groups. The average norepinephrine infusion was 0.143 mcg/kg/min. The NE group showed higher urine output (p = 0.016) and continuous increment in the mean arterial pressure compared to the baseline (p = 0.043). There were no differences in the remaining hemodynamic variables, fluid requirements, or furosemide administration. Conclusion: early norepinephrine infusion in children submitted to MV improves mean arterial pressure and increases urine output. These effects were attributed to reversion of vasoplegia induced by the sedative and analgesic drugs. .

Objetivo: avaliar os efeitos da infusão de noradrenalina (NA) em crianças submetidas a ventilação mecânica (VM) requerendo infusão contínua de sedoanalgesia. Métodos: estudo duplo cego, randomizado e placebo controlado envolvendo crianças de 1 mês a 12 anos, admitidas em uma UTI pediátrica brasileira com a expectativa de necessidade de VM e sedoanalgesia por, no mínimo, 5 dias. As crianças foram randomizadas a receber infusão de NA (0,15 mcg/kg/min) ou solução salina, iniciadas nas primeiras 24 horas de VM e mantidas por 72 horas. Comparamos as variáveis hemodinâmicas, oferta hídrica, função renal e débito urinário entre os dois grupos. Resultados: 40 crianças foram alocadas aos grupos NA e placebo, sem diferenças nas características basais, achados laboratoriais, escore PRISM II, tempo de VM ou mortalidade. A infusão média de NA foi 0,143 mcg/kg/min. O grupo NA apresentou maior débito urinário (p = 0,016) e aumento constante da pressão arterial média quando comparado aos níveis basais (p = 0,043). Não se observou diferenças nas demais variáveis hemodinâmicas, reposição hídrica ou no uso de furosemida. Conclusão: infusão precoce de NA em crianças submetidas a VM em uso sedoanalgesia promove aumento na pressão arterial média e aumento da diurese. Esses efeitos são atribuídos à reversão da vasoplegia induzida pelas drogas sedativas e analgésicas. .

Stress-related hormone norepinephrine induces interleukin-6 expression in GES-1 cells

In the current literature, there is evidence that psychological factors can affect the incidence and progression of some cancers. Interleukin 6 (IL-6) is known to be elevated in individuals experiencing chronic stress and is also involved in oncogenesis and cancer progression. However, the precise mechanism of IL-6 induction by the stress-related hormone norepinephrine (NE) is not clear, and, furthermore, there are no reports about the effect of NE on IL-6 expression in gastric epithelial cells. In this study, we examined the effect of NE on IL-6 expression in immortalized human gastric epithelial cells (GES-1 cells). Using real-time PCR and enzyme-linked immunoassay, we demonstrated that NE can induce IL-6 mRNA and protein expression in GES-1 cells. The induction is through the β-adrenergic receptor-cAMP-protein kinase A pathway and mainly at the transcriptional level. Progressive 5′-deletions and site-directed mutagenesis of the parental construct show that, although activating-protein-1 (AP-1), cAMP-responsive element binding protein (CREB), CCAAT-enhancer binding protein-β (C/EBP-β), and nuclear factor κ-light-chain-enhancer of activated B cells (NF-κB) binding sites are all required in the basal transcription of IL-6, only AP-1 and CREB binding sites in the IL-6 promoter are required in NE-induced IL-6 expression. The results suggest that chronic stress may increase IL-6 secretion of human gastric epithelial cells, at least in part, by the stress-associated hormone norepinephrine, and provides basic data on stress and gastric cancer progression.

High dilutions of homeopathic remedies induce relaxation of rat aorta precontracted with noradrenalin

BACKGROUND Homeopathic potencies have been reported to produce alteration of contraction in isolated rat ileum in an organ bath. Potentized homeopathic drugs like Lycopus V and Aurum met are used for the treatment of hypertension. AIM The purpose of this study is to see whether Lycopus V 30 CH and Aurum met 30 CH could produce relaxation of isolated rat aorta in the organ bath. METHODS The aorta of rats were dissected out, placed in Krebs-Henseleit solution, cleared of connective tissue and endothelium and cut into 2-2.5 mm long rings. The rings were fixed in organ baths with the upper end connected by a string to an isometric transducer which was finally attached through a data acquisitation equipment to a computer. Aurum met 30 CH Lycopus V 30 CH, and their medium 90% ethanol were added separately to the bathing fluid containing the aorta rings which were precontracted with noradrenalin (NA). RESULTS Both the drugs produced significant relaxation of the aorta (p<0.001) precontracted with NA (10-7 M). The control did not show any marked effect on the NA induced contraction of aorta. CONCLUSION A potentised drug is thought to be specifically structured water which can transform the water structure in the bathing fluid and the isolated tissue immersed in the fluid into its own form. This in turn produces the observed relaxation. Both Lycopus V 30 CH and Aurum met 30 CH are effective in reducing NA induced contraction of rat aorta. Drugs can directly act on the isolated rat aorta without any system of influence. KEY WORDS High dilution drug, isolated aorta, hypertension, noradrenalin.

Introdução e objetivo: Segundo alguns estudos, diluições homeopáticas alteram a contratilidade de íleo isolado de rato, em banho de órgãos. Os medicamentos homeopáticos como Aurum metallicum Lycopus virginicus são usados no tratamento da hipertensão. O objetivo deste estudo foi determinar se Lycps 30 cH e Aur 30 cH podem induzir o relaxamento da aorta isolada de ratos, em banho de órgãos. Métodos: A aorta foi dissecada e, livre de tecido conjuntivo e endotelio, foi colocada em solução de Krebs-Henseleit, sendo seccionada em anéis de 2 a 2,5 cm de comprimento. Os anéis foram fixados em banho de órgãos, a extremidade superior ligada por um cabo a um transdutor isométrico, por sua vez ligado a dispositivos de registro de dados em um computador. Aur 30 cH, Lycps 30 cH e etanol 90%, foram adicionados separadamente ao líquido do banho contendo os anéis de aorta previamente contraídas pela noradrenalina (NA) ou norpinefrina (NE). Resultados: Os dois medicamentos testados induziram relaxamento significativo (p <0,001), do preparada de aorta contraída por NA (10-7 M), enquanto que a solução de controle não produziu efeitos significativos. Conclusão: Ambas as drogas foram usadas em diluições homeopáticas demasiado elevadas para admitir a presença de moléculas da substância original. Assim, o mecanismo farmacológico tradicional envolvendo as moléculas da droga e receptores no músculo liso da aorta deve ser descartado. Embora reconhecidamente diferente, o mecanismo envolvido permanece desconhecido. Lycps 30 e Aur 30 CH mostraram-se eficazes na redução da contratilidade da aorta de ratos, induzida por NA. As drogas podem agir diretamente na aorta isolada de ratos sem influência sistêmica.

Regulação autonômica das propriedades mecânicas em bioprótese valvar porcina / Autonomic regulation of mechanical properties in porcine mitral valve cusps / Regulación autonómica de las propiedades mecánicas en bioprótesis valvular porcina

FUNDAMENTO: A presença de nervos nas válvulas cardíacas foi demonstrada pela primeira vez há décadas e identificadas em subpopulações: simpáticas e parassimpáticas, e, portanto, é esperado que as válvulas sejam grandemente afetadas pelos nervos autônomos. Entretanto, poucos estudos têm se concentrado na regulação de válvulas cardíacas pelo sistema nervoso autônomo. OBJETIVO: Buscamos identificar o papel do sistema nervoso autônomo na regulação das propriedades mecânicas dos tecidos de válvulas mitrais porcinas. MÉTODOS: As propriedades mecânicas dos folhetos de válvulas mitrais porcinas foram avaliados em resposta à norepinefrina (NE) e acetilcolina (ACH), os principais neurotransmissores. Ao mesmo tempo, fentolamina (FENT), metoprolol (Metop), atropina (Atrop) e desnudamento endotelial foram adicionados ao sistema reativo. RESULTADOS: Sob condições fisiológicas, a rigidez não foi afetada pelo desnudamento endotelial (p > 0,05). A NE significantemente aumentou a rigidez valvar por aumento de 10 vezes na concentração (10-6 vs 10-7, p < 0,05; 10-5 vs 10-6, p < 0,05). Essa resposta foi amenizada por FENT, Metop ou desnudamento endotelial (p < 0,05); entretanto, manteve-se aumentada de maneira significante quando comparada aos Controles (p < 0,05). A ACH causou uma diminuição na rigidez acompanhada por um aumento em sua concentração (alteração significante na rigidez por aumento de 10 vezes na concentração de ACH, 10-6 vs Controle, p < 0,05; 10-5 vs 10-6, p < 0,05), que foi revertida pelo desnudamento endotelial e Atrop (p > 0,05 vs Controle). CONCLUSÃO: Esses achados ressaltam o papel do sistema nervoso autônomo na regulação das propriedades mecânicas das cúspides de válvula mitral porcina, o que reforça a importância do estado nervoso autônomo no funcionamento ideal da válvula.

BACKGROUND: The presence of nerves in heart valves was first depicted decades ago and identified into subpopulations: sympathetic, parasympathetic. So valves are expected to be greatly affected by the autonomic nerves. However, few studies have focused on the regulation of heart valves by the autonomic nervous system. OBJECTIVE: We sought to identify the role of the autonomic nervous system in the regulation of the mechanical properties of porcine mitral valve tissues. METHODS: Mechanical properties of porcine mitral valve leaflets were evaluated in response to norepinephrine (NE) and acetylcholine (ACH), the main neurotransmitters. At the same time, phentolamine (Phent), metoprolol (Metop), atropine (Atrop) and endothelial denudation were added to the reactive system. RESULTS: Under physiological conditions, the stiffness was not affected by endothelial denudation (p > 0.05). NE elevated the valve stiffness significantly per 10-fold increase in concentration (10-6 vs 10-7, p < 0.05; 10-5 vs 10-6, p < 0.05). This response was mitigated by Phent, Metop or endothelial denudation (p < 0.05), however, it was still increased significantly when compared to Controls (p < 0.05). ACH caused a decrease in stiffness accompanied by an increase in its concentration (significant change in stiffness per 10-fold increase in ACH concentration, 10-6 vs Control, p < 0.05; 10-5 vs 10-6, p < 0.05), which were reversed by endothelial denudation and Atrop (p > 0.05 vs Control). CONCLUSION: These findings highlight the role of the autonomic nervous system in the regulation of the mechanical properties of porcine mitral valve cusps, which underline the importance of autonomic nervous status for optimal valve function.

FUNDAMENTO: La presencia de nervios en las válvulas cardíacas quedó demostrada por primera vez hace algunas décadas e identificadas en sub-poblaciones: simpáticas y parasimpáticas y por lo tanto, lo que se espera es que las válvulas reciban una gran afectación de los nervios autónomos. Sin embargo, pocos estudios se han concentrado en la regulación de válvulas cardíacas a través del sistema nervioso autónomo. OBJETIVO: Buscamos identificar el papel del sistema nervioso autónomo en la regulación de las propiedades mecánicas de los tejidos de las válvulas mitrales porcinas. MÉTODOS: Las propiedades mecánicas de las capas de válvulas mitrales porcinas fueron evaluadas en respuesta a la norepinefrina (NE) y a la acetilcolina (ACH), los principales neurotransmisores. Igualmente, la fentolamina (FENT), el metoprolol (Metop), la atropina (Atrop) y la denudación endotelial también se añadieron al sistema reactivo. RESULTADOS: Bajo condiciones fisiológicas, la rigidez no se afectó por el denudación endotelial (p > 0,05). La NE aumentó significativamente la rigidez valvular con un aumento de 10 veces en la concentración (10-6 vs 10-7, p < 0,05; 10-5 vs 10-6, p < 0,05). Esa respuesta fue amenizada por FENT, Metop o denudación endotelial (p < 0,05); pero se mantuvo aumentada de manera significativa cuando se le comparó con los Controles (p < 0,05). La ACH causó una disminución en la rigidez acompañada por un aumento en su concentración (alteración significativa en la rigidez por el aumento en 10 veces de la concentración de ACH, 10-6 vs Control, p < 0,05; 10-5 vs 10-6, p < 0,05), que fue revertida por la denudación endotelial y Atrop (p > 0,05 vs Control). CONCLUSIÓN: Esos hallazgos destacan el rol del sistema nervioso autónomo en la regulación de las propiedades mecánicas de las cúspides de la válvula mitral porcina, lo que refuerza la importancia del estado nervioso autónomo en el funcionamiento ideal de la válvula.

Role of norepinephrine & angiotensin II in the neural control of renal sodium & water handling in spontaneously hypertensive rats.

Background & objectives: A wealth of information concerning the essential role of renal sympathetic nerve activity (RSNA) in the regulation of renal function and mean arterial blood pressure homeostasis has been established. However, many important parameters with which RSNA interacts are yet to be explicitly characterized. Therefore, the present study aimed to investigate the impact of acute renal denervation (ARD) on sodium and water excretory responses to intravenous (iv) infusions of either norepinephrine (NE) or angiotensin II (Ang II) in anaesthetized spontaneously hypertensive rats (SHR). Methods: Anaesthetized SHR were acutely denervated and a continuous iv infusion of NE (200 ng/min/kg) or Ang II (50 ng/min/kg) was instigated for 1 h. Three 20-min urine clearances were subsequently collected to measure urine flow rate (UV) and absolute sodium excretion (UNaV). Results: Higher UV and UNaV (P<0.05) were observed in denervated control SHR as compared to innervated counterparts. The administration of NE or Ang II to innervated SHR produced lower UV and UNaV (P<0.05 vs. innervated control SHR). Lower diuresis/natriuresis response to ARD was observed in NE-treated SHR compared to denervated control SHR (P<0.05). Salt and water excretions in denervated NE-treated SHR, however, were significantly higher (P<0.05) relative to the excretion levels in control denervated SHR. Conversely, there was a higher (all P<0.05) diuresis/natriuresis response to ARD when Ang II was administered to SHR compared to denervated control or innervated Ang II-treated SHR. Interpretation & conclusions: NE retains its characteristic antidiuretic/antinatriuretic action following ARD in SHR. Typical action of Ang II on salt and water excretions necessitates the presence of an intact renal innervation. Ang II is likely to facilitate the release of NE from renal sympathetic nerve terminals through a presynaptic site of action. Moreover, there is a lack of an immediate enhancement in the renal sensitivity to the actions of NE and Ang II following ARD in a rat model of essential hypertension.

Age-related changes in carotid vascular responses to noradrenaline and nitric oxide synthase inhibitor

The aim of the present work was to study whether age alters the constrictor responses evoked by the sympathetic transmitter Noradrenaline in the carotid circulation in the rat. Another aim was to test whether age changes the influence of tonically synthetised nitric oxide [NO] on arterial blood pressure [ABP] and on carotid circulation. Further, to investigate the effect of NO synthesis inhibition on carotid vascular responses euoted by noradrenaline in three age groups of rats. In anaesthetised rats aged 4-5, 10-12 and 42-44 weeks [young, mature, middle-aged respectively], carotid blood flow [CBF] and carotid vascular conductance [CVC] were recorded during infusion of noradrenaline [2.5/micro g.kg[-1]], before and after a bolus dose of the nitric oxide synthase inhibitor L-NAME [10mg.kg[-1]]. In mature and middle-aged rats, noradrenaline infusion increased mean ABP to 180mmHg, but only to 150mmHg in young rats. Concomitantly, CVC decreased more in mature and middle-aged, than in young rats: CBF remained constant in young, but decreased in mature and middle-aged rats. NO synthase inhibition produced similar increases in baseline ABP in all groups, but decreased CVC and CBF more in mature and middle-aged rats. Following NO inhibition, noradrenaline infusion increased ABP to similar levels as before in young and mature rats, but to higher levels in middle-aged rats. Further, CVC fell in young and mature, but not in middle-aged rats, in whom CBF increased with ABP.Thus, in young rats there was a weak noradrenaline-evoked pressor response and decrease in CVC. By contrast, in mature and middle-aged rats, noradrenaline evoked a strong pressor response and decrease in CVC. In young and mature rats, NO seems not to limit the noradrenaline-evoked increases in ABP or decreases in CVC. However, by middle age NO limits noradrenaline-evoked pressor response and prevents breakthrough of CBF Autoregulation. The three age groups showed good autoregulatory response of carotid circulation during a pressor response induced by noradrenaline. However, the constrictor responses evoked by noradrenaline is weak in youngs before the age of sexual maturity. On the other hand, by middle-age and well before old age, the constrictor influences of noradrenaline in carotid circulation have begun to weaken. Moreover, by middle age, the dilator influence of NO helps to prevent breakthrough of Autoregulation of CBF at the upper end of the range

Oral contraceptive-induced high blood pressure is prevented by renin-angiotensin suppression in female rats but not by sympathetic nervous system blockade.

The use of oral contraceptive (OC) steroids is associated with high blood pressure, although mechanisms responsible are still unclear. This study sought to investigate the possible roles that renin-angiotensin system (RAS) and sympathetic nervous system (SNS) may play in the development of OC-induced hypertension. Administration of OC led to significant increases in blood pressure, heart weight and significant decrease in urinary output in OC-treated and OC+clonidine-treated groups but not in OC+captopril-treated group. The pressor response to angiostensin II was significantly greater in the OC-treated rats than in the control rats. However, the pressor responses induced by norepinephrine were not significantly affected by OC administration. The results of the present study demonstrate that OC-induced high blood pressure is associated with cardiac hypertrophy, enhanced pressor response to angiotensin II and preserved pressor response to sympathetic activation. The study also suggests that the development of the OC-induced hypertension and cardiac hypertrophy is mediated by RAS, but not by SNS.

Efecto agudo de las estatinas sobre la relajación vascular in vitro mediada por acetilcolina y nitroprusiato en vasos usados en la revascularización coronaria / Acute effect of statins on acetylcholine and nitroprusside induced vascular relaxation of vessels used for revascularization purposes

Antecedentes: Uno de los efectos pleiotrópicos de las estatinas es su capacidad de inducir relajación vascular tanto in Vitro como in Vivo cuando son administradas crónicamente, pero el efecto agudo en los vasos no ha sido estudiado en detalle. Objetivos: Evaluar los efectos agudos de las estatinas en la relajación vascular in vitro mediada por acetilcolina (ACh) y nitroprusiato en vasos usados en revascularización coronaria. Método: Se analizaron segmentos de vasos obtenidos de pacientes programados para cirugía de revascularización coronaria. Cada segmento de arteria radial, mamaria y vena safena fue dividido en dos, uno de ellos incubado durante dos horas con estatinas y el otro con solución buffer. Luego, se contrajo cada vaso con 80 mM de KCl y posteriormente con 10-4 M de noradrenalina seguido de administración de dosis acumulativas de ACh para inducir la relajación del vaso. Después de lavados repetidos, se contrae con la misma dosis de noradrenalina y se relaja con dosis creciente de nitroprusiato (NP). Resultados: La administración de KCl produjo una mayor contracción, aunque no significativa, en arterias radiales en relacióna los otros vasos, tanto en los incubados con estatinas como el grupo control. La noradrenalina produjo una mayor contracción no significativa en venas safenas; sin embargo no hubo diferencias entre los segmentos incubados con y sin estatinas. La vasodilatación por acetilcolina no se vio afectada por estatinas. La vasodilatación inducida por nitroprusiato no se modificó en presencia de estatinas en arterias radiales o mamaria. Sin embargo el tratamiento con estatina disminuyó significativamente la relajación inducida por nitroprusiato en la vena safena (p<0,05). Conclusión: Los resultados de este trabajo demuestran una respuesta diferencial de los vasos usados en revascularización coronaria frente al efecto agudo de estatina.

Influência da noradrenalina na mortalidade dos idosos com choque séptico / Norepinephrine influence on mortality in elderly with septic shock

Fundamentos: Permanece controverso o uso da noradrenalina(NA) no tratamento do choque séptico(CS) em idosos, pela possível vasoconstrição excessiva e consequentemente hipoperfusão tissular. Objetivo: Analisar se o emprego da NA se associa à maior mortalidade na unidade de terapia intensiva(UTI), em idosos com CS. Métodos: Coorte prospectiva de 67 pacientes com CS e idade maior que 65 anos, monitorados com cateteres na artéria pulmonar e em vaso periférico, por período de 32 meses. Todos os pacientes utilizaram suporte ventilatório, cobertura empírica com antibióticos de largo espectro e ressuscitação volêmica. Se a pressão arterial média permanecesse menor que 70 mmhg, iniciava-se 5 ug/kg/min de dopamina(até 20 ug/kg/min), substituída por 0,1 ug/kg/min de NA(até 5 ug/kg/min) e dobutamina, na falência cardíaca. Avaliou-se: o escore APACHE II, falências orgânicas(critérios de Le Gall), troponina I, tempo de permanência na UTI, sítio primário da infecção, uso de dopamina, NA e dobutamina. Na análise estatística foram utilizados os testes t de Student, o qui-quadrado, e análise de sobrevida de Kaplan-Meier, com significância de 5 por cento. Resultados: A média da idade foi de 80 anos, sendo 51 por cento do sexo feminino. A média dos escores do APACHE II foi de 19 e do tempo de permanência de 18 dias. Ocorreram 39 óbitos. A sepse pulmonar foi prevalente(70 por cento). As falências pulmonar e cardíaca ocorreram em 69 por cento e 46 por cento dos casos, respectivamente. A troponina I foi positiva em 33 por cento. Todos fizeram uso de dopamina seguida de NA(dobutamina + NA em 12 por cento). O APACHE II (p igual 0,001), o número de falências orgânicas(p igual 0,006), a dose maior que 0,5 ug/kg/min de NA(p igual 0,001), a positividade da troponina I(p igual 0,006), o tempo de uso de dopamina(p igual 0,004) e o tempo de permanência na UTI(p igual 0,001) mostraram associação com a mortalidade. O emprego de aminas, o sítio de infecção e a idade não se correlacionaram com o óbito. Não houve correlação com a presença de falência cardíaca. Conclusão: O uso de NA em doses menores ou iguais a 0,5 ug/kg/min não se associou com a mortalidade, porém a mortalidade se correlacionou com a presença de duas ou mais falências orgânicas nos idosos, com choque séptico

Mechanisms of depressor effect of norepinephrine injected into subnucleus commissuriu of nucleus solitarius tractus in rabbits / 华中科技大学学报（医学）（英德文版）

This experiment aimed to investigate the effect of adrenergic system in the subnucleus commissuriu of nucleus solitrius tractus (CNTS) on renal nerve discharges. Norepinephrine (NE) was microinjected into the CNTS of rabbits and mean arterial blood pressure (MAP) and renal nerve discharges (FRND) were synchronously recorded. The results indicated that (1) microinjection of norepinephine into the CNTS of rabbit could significantly attenuate the frequency of renal nerve discharge, and at the same time decrease markedly the mean arterial pressure. (2) Microinjection of 0.3 nmol yohimbin into CNTS had no significant influence on FRND and MAP, but could attenuate and even reverse the effects of NE on FRND and MAP. These results suggest that microinjection of NE into CNTS may activate the alpha-adrenorecptor located in CNTS and secondarily produce a depressor effect by attenuating the activity of periphenal sympathetic nervous system.

Why the medial preoptic area is important for sleep regulation.

The medial preoptic area (mPOA) is one of the many areas in the brain that control sleep. Apart from sleep, the mPOA is important for the regulation of body temperature, and other important body functions aimed at energy homeostasis. In sleep regulation, the major function of this area is to maintain sleep. Though the mPOA controls sleep and body temperature through independent neuronal circuits, it is essential for organising the sleep architecture, as per the thermoregulatory requirement. The functional integrity of the mPOA may be essential for the regulation of energy homeostasis, in response to alterations in the ambient temperature, heat producing physical activity and sleep-wakefulness. Thus, the mPOA forms part of the brain that integrates regulations aimed at preservation of self. The mPOA is important for maintaining the "set point" for not only body temperature, but it is also important for maintaining the "set point" for several physiological parameters including sleep-wakefulness.

Inhibitory effect of manganese on contraction of isolated rat aorta.

The effects of MnCl2 on vascular smooth muscle contraction induced by noradrenaline (NA) and KCl were investigated. Rings segments from rat aorta were isolated and changes in isometric tension recorded. MnCl2 (10 microM and 1 mM) significantly attenuated the contractile responses to NA and KCI. There were also reductions in the contractile responses to CaCl2 in NA- and KCl-stimulated rings, after pretreatment with MnCl2. The magnitude of the phasic contraction to NA was significantly reduced in presence of MnCl2. The results suggest that MnCl2 inhibits vascular smooth muscle contraction by influencing a Ca2+-mediated mechanism.

Ex vivo reactivity of the ovarion vascular bed to noradreualine and carbachol during ovarian hyperstimulation syndrome

To study reactivity of the ovarian vascular bed to noradrenaline and carbachol during an experimentally induced ovarian hyperstimulation syndrome [OHSS] in rabbits. Materials and Rabbits were treated with human menopausal gonadotropin [75 IU] daily for 6 days, followed by human chorionic gonadotropin [2,500 IU] to induce OHSS. The ovarian vascular bed was isolated and perfused with physiological solution and its reactivity to injected noradrenaline and acetylcholine was examined. The mean weight of the hyperstimulated ovary was 2.85 +/- 0.5 g compared to 0.25 +/- 0.1 g for the control rabbits. There was no significant difference in [a] the basal perfusion pressure of the ovarian vascular bed ex vivo; [b] the potency of, or maximum response to, noradrenaline, and [c] agonist dissociation constant or receptor density. Carbachol induced significantly greater vasodilation in ovarian vascular beds from hormone-treated rabbits, indicating a greater role for nitric oxide in this syndrome, as further supported by the observation that NW-nitro-L-arginine methyl ester hydrochloride [L-NAME] was more effective against carbachol-induced response in hormone-treated rabbits. In the rabbit model of OHSS, carbachol produced an increased ex vivo vascular response but noradrenaline did not

Metabolic markers following beta-adrenoceptor agonist infusion in footshock-stressed rats

Stress hormones can alter metabolic functions in adipose tissue and liver, as well as the sensitivity of rat white adipocytes and rat atrial responses to ß-adrenergic agonists. In this study, we examined the effects of three daily footshock stress sessions on the plasma corticosterone, glucose, glycerol and triacylglycerol levels of fed, conscious male rats, and on the plasma glucose, glycerol and triacylglycerol levels of the same rats following iv infusions of ß-adrenergic agonists (isoproterenol: 0.4 nmol kg-1 min-1, noradrenaline: 5.0 æg kg-1 day-1, and BRL 37344 ([+ or -]-[4-(2-[(2-[3-chlorophenyl]-2-hydroxyethyl)amino]propyl)phenoxy]acetic acid), a selective ß3-adrenoceptor agonist: 0.4 nmol kg-1 min-1). Plasma corticosterone levels increased significantly after each stress session, while triacylglycerol levels increased after the first session and glucose increased after the second and third sessions. Glycerol levels were unaltered after stress. These results suggest that repeated footshock stress may induce a metabolic shift from triacylglycerol biosynthesis to glucose release by hepatic tissue, with glycerol serving as one of the substrates in both pathways. Stressed rats were more sensitive to infusion of noradrenaline plus prazosin and to infusion of isoproterenol, with elevated plasma glucose, glycerol and triacylglycerol levels. The higher sensitivity of stressed rats to isoproterenol and noradrenaline was probably related to the permissive effect of plasma corticosterone. Only BRL 37344 increased plasma glycerol levels in stressed rats, probably because ß3-adrenoceptors are not involved in hepatic triacylglycerol synthesis, thus allowing glycerol to accumulate in plasma