Vasorelaxant activity and acute toxicity of the ethanolic extract of Zanthoxylum rhoifolium Lam leaves

The study evaluated the vasorelaxant effect induced by the ethanolic extract of the leaves of Zanthoxylum rhoifolium Lam (EEtOH-Zr/leaves). Wistar rats were treated with the leaf extract containing a single dose of 2,000 mg / kg, v.o. After 14 days, the animals were anesthetized for blood collection and subsequent analysis of the biochemical parameters; they were then euthanized (sodium pentobarbital-100 mg/kg, i.p.) for the removal and morphological analysis of the heart, lung, liver and kidney. The vasorelaxation activity the and vascular reactivity of EEtOH-Zr/leaves were evaluated on artery mesenteric rings isolated from rats. The extract showed no signs of toxicity and no significant difference in the values of the biochemical parameters between the control group and the group of treated animals. In the evaluation of pharmacological activity in the smooth muscle, the EEtOH-Zr/leaves caused vasorelaxant effect on the tonic contraction induced by phenylephrine in mesenteric artery preparations in the presence (pD2=2.17±0.05 µg/mL; Emax=99.8±5.2%) and absence (pD2=2.14±0.05 µg/mL; Emax=95.3±6.4%) of the vascular endothelium. Oral administration of EEtOH-Zr/leaves reduced the contraction induced by the cumulative addition of PHE. It is concluded that the EEtOH-Zr/leaves promote vasorelaxation and reduce vascular reactivity of adrenergic alpha-1 agonist in the mesenteric artery. The results did not show toxic effects of the extract.

Effects of a Single Bout of Resistance Exercise in Different Volumes on Endothelium Adaptations in Healthy Animals / Efeitos de uma Sessão de Exercício Resistido em Diferentes Volumes sobre Adaptações Endoteliais em Animais Saudáveis

Abstract Background: Resistance exercise (RE) has been recommended for patients with cardiovascular diseases. Recently, a few studies have demonstrated that the intensity of a single bout of RE has an effect on endothelial adaptations to exercise. However, there is no data about the effects of different volumes of RE on endothelium function. Objective: The aim of the study was to evaluate the effects of different volumes of RE in a single bout on endothelium-dependent vasodilatation and nitric oxide (NO) synthesis in the mesenteric artery of healthy animals. Methods: Male Wistar rats were divided into three groups: Control (Ct); low-volume RE (LV, 5 sets x 10 repetitions) and high-volume RE (HV, 15 sets x 10 repetitions). The established intensity was 70% of the maximal repetition test. After the exercise protocol, rings of mesenteric artery were used for assessment of vascular reactivity, and other mesenteric arteries were prepared for detection of measure NO production by DAF-FM fluorescence. Insulin responsiveness on NO synthesis was evaluated by stimulating the vascular rings with insulin (10 nM). Results: The maximal relaxation response to insulin increased in the HV group only as compared with the Ct group. Moreover, the inhibition of nitric oxide synthesis (L-NAME) completely abolished the insulin-induced vasorelaxation in exercised rats. NO production showed a volume-dependent increase in the endothelial and smooth muscle layer. In endothelial layer, only Ct and LV groups showed a significant increase in NO synthesis when compared to their respective group under basal condition. On the other hand, in smooth muscle layer, NO fluorescence increased in all groups when compared to their respective group under basal condition. Conclusions: Our results suggest that a single bout of RE promotes vascular endothelium changes in a volume-dependent manner. The 15 sets x 10 repetitions exercise plan induced the greatest levels of NO synthesis.

Resumo Fundamentos: O exercício resistido (ER) tem sido recomendado para pacientes com doenças cardiovasculares. Recentemente, alguns estudos demonstraram que a intensidade de uma sessão de ER exerce um efeito sobre a disfunção endotelial. No entanto, não há dados sobre os efeitos de diferentes volumes de ER sobre a função endotelial. Objetivo: O objetivo deste estudo foi avaliar os efeitos de diferentes volumes de ER, realizados em uma única sessão, sobre a vasodilatação dependente do endotélio e síntese de óxido nítrico (NO) em artéria mesentérica de animais saudáveis. Métodos: Ratos Wistar machos foram divididos em três grupos: Controle (Ct); baixo volume (BV, 5 séries x 10 repetições) e alto volume de ER (AV, 15 séries x 10 repetições). Foi estabelecida a intensidade de 70% do teste de repetição máxima. Após o protocolo de exercício, anéis de artéria mesentérica foram utilizados na avaliação da reatividade vascular, e outras artérias mesentéricas foram preparadas para a detecção da produção de NO por fluorescência com para do DAF-FM. A resposta à insulina pela síntese de NO foi avaliada estimulando-se os anéis vasculares com insulina (10nM). Resultados: A resposta máxima do relaxamento induzido por insulina foi aumentada somente no grupo AV em comparação ao grupo Ct. Além disso, a inibição da síntese do NO (L-NAME), aboliu completamente o relaxamento vascular induzido por insulina em ratos exercitados. A produção de NO mostrou um aumento dependente do volume no endotélio e no músculo liso. No endotélio, apenas os grupos Ct e BV mostraram aumento significativo na síntese de NO quando comparado aos seus respectivos grupos sob condição basal. No entanto, no músculo liso, a fluorescência foi aumentada em todos os grupos quando comparados aos seus respectivos grupos sob a condição basal. Conclusões: Nossos resultados sugerem que uma única sessão de ER foi capaz de promover adaptações no endotélio vascular. Além disso, nós observamos que este efeito é volume-dependente e o volume de 15 séries x10 repetições induziu o maior aumento na síntese de NO.

Avaliação dos efeitos vasculares e expressão de mRNA de receptores de drogas vasoconstritoras em leito arterial mesentérico de ratos normotensos, diabéticos, hipertensos renais um-rim, um clip (1R-1C) e 1R-1C diabéticos / Vascular reactivity and vasoconstrictor drugs receptors RNAmexpression on mesenteric artery bed of normotensive, diabetic, 1K-1C hypertensive and 1K-1C hypertensive-diabetic rats

O presente trabalho teve como objetivo avaliar e comparar a reatividade vascular de agentes vasoconstritores presentes nas soluções anestésicas locais (Adrenalina - vasoconstrição e vasodilatação; Felipressina - vasoconstrição), nas doses de 80, 160, 320, 640 e 1280ng (adrenalina) ou 0,25; 0,5; 1; 2 e 4 x10-3UI (felipressina), em leito arterial mesentérico deratos normotensos, diabéticos, hipertensos renais um-rim, um-clip (1R-1C) e hipertensos1R-1C-diabéticos. E correlacionar tal reatividadecom expressão de RNAm dos receptores 1A e 2- adrenérgicos, V1A para vasopressina e AT1A, AT1Be AT2 para angiotensina II visando verificar se a hipertensão arterial e o diabetes mellitus provocam alteração em modelo indutivo e isogênico. Ratos Wistar pesando 110-160g, foram anestesiados com mistura de quetamina e xilazina (50+10mg/ml/kg de peso), tiveram seu abdômen aberto e receberam um clip de prata com abertura 0,25mm na artéria renal esquerda, removendo-se cirurgicamente o rim direito (ratos 1R-1C). Após 14 dias, receberam injeção subcutânea de estreptozotocina (50 e 60mg/kg de peso) para indução do diabetes mellitus sendo a glicemia testada pela veia caudal previamente aos experimentos (diabéticos). Após 30-42 dias da implantação do clip, todos os grupos foram novamente anestesiados e implantou-se cânula de polietileno (PE-50) na artéria carótida esquerda para registro direto da pressão arterial. Após registro da pressão os animais tiveram a artéria principal mesentérica exposta e canulada. O leito arterial mesentérico foi então isolado e colocado em banho com solução nutritiva de Krebs a 37ºC. O cateter foi conectado ao sistema de registro computadorizado (PowerLab®) utilizando software específico (Chart 5Pro ®). Analisaram-se: a pressão máxima (vasoconstrição) e mínima (vasodilatação), o tempo necessário para atingir esse valor, duração total da resposta, integral e integral sobre a linha de base. Os dados foram submetidos à análise de variância de medidas repetidas (ANOVA), seguida do teste de Holm-Sidak (distribuição normal) ou de Mann-Whitney (nãoparamétrico), quando apropriado, nível de significância de 5%. Todas as respostas máximas de vasoconstrição apresentaram comportamento dose-dependente, contudo, para os quatro grupos estudados, a resposta vasoconstritora para adrenalina foi significativamente superior à felipressina (p<0,05). Diabetes e hipertensão reduziram a resposta vasoconstritora da adrenalina e da felipressina, valores de integral sobre a linha de base, respectivamente para grupo controle, diabético, hipertenso e hipertenso-diabético: 2462±465; 1511±236; 2542± 5456 e 3749±819mmHg.s (p<0,05) para adrenalina e 3749 ± 708; 746 ± 103; 1647 ± 422; 1359 ± 591 mmHg.s (p<0,05) para felipressina. Tanto o diabetes quanto a hipertensão, associadas ou não, aumentaram significativamente o tempo para atingir a pressão máxima de vasoconstrição e a duração (p<0,05). As artérias mesentéricas de ratos diabéticos, hipertensos e diabéticos-hipertensos apresentaram expressão significativamente aumentada dos receptores 1Aadrenérgico, AT1B e AT2 para angiotensina II (p<0,05), enquanto receptor AT1A estava com a expressão aumentada apenas nos grupos diabéticos. A expressão do receptor 1A-adrenérgico é discrepante com os achados funcionais, o que pode ser justificado pela fase crônica da doença em que a PCR foi realizada. É possível correlacionar os dados obtidos com a menor atividade vasoconstritora da felipressina observada clinicamente. A maior sensibilidade às moléculas vasoconstritoras pode explicar a maior tendência de pacientes diabéticos desenvolverem hipertensão. A partir dos dados obtidos pode-se concluir que a adrenalina é o vasoconstritor mais potente que a felipressina e ambas as moléculas tem seus efeitos reduzidos em pacientes hipertensos e diabéticos, o que reforça a indicação de se utilizar anestésicos locais associados a vasoconstritores nestas populações.(AU)

The main goal of this study wasto evaluate and compare vasoconstrictor agents present in local anesthetic solutions (Epinephrine - vasoconstriction and vasodilation, Felypressin - vasoconstriction) vascular reactivity on mesenteric artery bed of normotensive, diabetic, renal hypertensive one-kidney-one-clip (1K1C) and hypertensive 1K1C diabetic rats. Dosagesstudied were 80, 160, 320, 640 and 1280ng (epinephrine) or 0,25; 0,5;1; 2 and 4 x 10-3UI (felypressin). Also, we aimed to correlate artery response with RNAm expression of 1A and 2-adrenoceptors, V1A vasopressin receptor and AT1A, AT1B e AT2 angiotensin receptors, in order to verify if arterial hypertension and diabetes can lead to alterations on a inductive and isogenic model. Wistar male rats weighing 110-160g were anaesthetized with a mixture of ketamine and xylazine (50+10mg/ml/kg), had their abdominal cavity opened and a silver clipwith 0.25-mm gap was implanted in the main left kidney artery, the right kidney was surgically removed (1K1C-rats). After 14 days, they received a subcutaneous injection of streptozotocin (50 and 60 mg/ml/kg) for inducing diabetes, whereas the glycemia was tested via the tail vein prior to surgery (diabetic rats). Around 30-42 after the clip was implanted, all the groups were anaesthetized again and a polyethylene (PE-50) cannula was implanted on the left carotid artery for direct arterial pressure register. After registering the pressure, the animals had their main mesenteric artery exposed and cannulated. The mesenteric artery bed was then isolated and transferred to a bath with Krebs nutritive solution at 37ºC. The catheter was connected to the computer register system (PowerLab®) using a specific software (Chart 5Pro ®). The following parameters were analyzed: maximum (vasoconstriction) and minimal pressure (vasodilating), the amount of time necessary to achieve this number, total duration of the reaction, integral and integral over baseline. The data was submitted to analysis of variance of repeated measures (ANOVA), followed by a Holm-Sidak (normal distribution) test or Mann Whitney (parametrics) test when suitable, with a significance level of 5%. All maximum vasoconstriction results presented dosage-dependant behavior, however, for the four groups tested, the vasoconstrictive result for epinephrine was significantly superior to felypressin (p<0,05). Diabetes and hypertension significantly reducedepinephrine and felypressin vasoconstrictor responses, integral above baseline, respectively, for control, diabetic, hypertensive and hypertensive-diabetic groups:2462±465; 1511±236; 2542± 5456 e 3749±819 mmHg.s (p<0.05, epinephrine) and 3749 ± 708; 746 ± 103; 1647 ± 422; 1359 ± 591 mmHg.s (p<0.05, felypressin). Both diabetes and hypertension, associated or not, significantly increased time necessary to achieve maximum vasoconstrictor response and its duration (p<0,05). Diabetic, hypertensive and hypertensive-diabetic mesenteric arteries presented 1A-adrenoceptor, AT1B and AT2 angiotensin II-receptor gene expression significantly increased when compared with control group (p<0,05), while AT1Areceptor presented this pattern only in diabetic groups.1A-adrenoceptor gene expression did not confirm functional data, probably due to chronic disease state in wich PCR was performed. A partir dos dados obtidos pode-se concluir que a adrenalina é o vasoconstritor mais potente que a felipressina e ambas as moléculas tem seus efeitos reduzidos em ratos hipertensos e diabéticos não tratados, o que reforça a indicação de se utilizar anestésicos locais associados a vasoconstritores nestas populações.Its possible to correlate our datawith reducedvasoconstrictor activity of felypressinin clinical use. Increased sensibility and receptor population for vasoconstrictor endogenous molecules could explain diabetic populations tendency to develop arterial hypertension. Our results suggest that epinephrine is more potent than felypressin and both vasoconstrictors presents reduced effects on diabetic and hypertensive patients, what reinforces vasoconstrictor associated with local anesthetic use in this population.(AU)

Effect of protective solutions and hydroxyethyl starch in the attenuation of the injuries of ischemia and reperfusion of splanchnic organs

PURPOSE: Vogt´s antioxidant solution (red blood cells, Ringer's solution, sodium bicarbonate, mannitol, allopurinol and 50% glucose) or its modification including hydroxyethyl starch (HES) were tested for the prevention of splanchnic artery occlusion shock. METHODS: Seventy rats were distributed in treatment (3), control (1), and sham (3) groups. Ischemia and reperfusion were induced by celiac, superior mesenteric and inferior mesenteric arteries occlusion for 40 min, followed by 60 min reperfusion or sham procedures. Controls received saline, both treatment and sham groups received the Vogt's solution, modified Vogt's solution (replacing Ringer's solution by HES), or HES. Mean arterial blood pressure (MABP), ileal malondialdehyde (MDA) and plasmatic MDA were determined, and a histologic grading system was used. RESULTS: At reperfusion, MABP dropped in all I/R groups. Only HES treatment was able to restore final MABP to the levels of sham groups. Plasmatic MDA did not show differences between groups. Ileum MDA was significantly higher in the control and treatment groups as compared to the sham group. Histology ranking was higher in the only in control group. CONCLUSIONS: Hydroxyethyl starch was able to prevent hemodynamic shock but not intestinal lesions. Both treatments with Vogt's solutions did not show any improvement. .

Serotonin contracts the rat mesenteric artery by inhibiting 4-aminopyridine-sensitive Kv channels via the 5-HT2A receptor and Src tyrosine kinase

Serotonin (5-hydroxytryptamine (5-HT)) is a neurotransmitter that regulates a variety of functions in the nervous, gastrointestinal and cardiovascular systems. Despite such importance, 5-HT signaling pathways are not entirely clear. We demonstrated previously that 4-aminopyridine (4-AP)-sensitive voltage-gated K+ (Kv) channels determine the resting membrane potential of arterial smooth muscle cells and that the Kv channels are inhibited by 5-HT, which depolarizes the membranes. Therefore, we hypothesized that 5-HT contracts arteries by inhibiting Kv channels. Here we studied 5-HT signaling and the detailed role of Kv currents in rat mesenteric arteries using patch-clamp and isometric tension measurements. Our data showed that inhibiting 4-AP-sensitive Kv channels contracted arterial rings, whereas inhibiting Ca2+-activated K+, inward rectifier K+ and ATP-sensitive K+ channels had little effect on arterial contraction, indicating a central role of Kv channels in the regulation of resting arterial tone. 5-HT-induced arterial contraction decreased significantly in the presence of high KCl or the voltage-gated Ca2+ channel (VGCC) inhibitor nifedipine, indicating that membrane depolarization and the consequent activation of VGCCs mediate the 5-HT-induced vasoconstriction. The effects of 5-HT on Kv currents and arterial contraction were markedly prevented by the 5-HT2A receptor antagonists ketanserin and spiperone. Consistently, alpha-methyl 5-HT, a 5-HT2 receptor agonist, mimicked the 5-HT action on Kv channels. Pretreatment with a Src tyrosine kinase inhibitor, 4-amino-5-(4-chlorophenyl)-7-(t-butyl)pyrazolo[3,4-d]pyrimidine, prevented both the 5-HT-mediated vasoconstriction and Kv current inhibition. Our data suggest that 4-AP-sensitive Kv channels are the primary regulator of the resting tone in rat mesenteric arteries. 5-HT constricts the arteries by inhibiting Kv channels via the 5-HT2A receptor and Src tyrosine kinase pathway.

ATP-sensitive potassium channels do not mediate vasorelaxation by acetylcholine or iloprost

The influence of glibenclamide(GBC), a blocker of ATP-sensitive K+ channells, on relaxation caused by cromakalin(CKL), acetylcholine (ACh) and iloprost (ILO) was assessed in aortic rings (AR) with (E+) or without endotheliium (E-) and in the perfused arterial mesentery (MES) of the rat. In AR preconstricted with noradrenaline, CKL(0.03-10 *M) and ILO (5.5 nM) caused graded vasodilations which were not modified by endothelium removal. ACh(0.01-3 *M) only relaxed E+AR preparations. GBC (3*M) markedly reduced responses to CKL in E+AR and E-AR, but did not affect vasodilation induceds by ILO in E-AR and by ACH in E+AR. In MES preconstricted with methoxamine, bolus injections of CKL (10 or 30 nmol) or ACh (0.03-1nmol) caused graded reductions of perfusion pressure. Only the responses to CKL were significantly inhibited by GBC (10 *M). We conclude that AR and MES contain functional ATP-sensitive K+ channels, which, however, do not play a significant role in the endothelium-dependent vasodilation triggered by ACh or in the endothelium-indipendent relaxation induced by ILO

Organic and inorganic calcium blockers on voltage and receptor operated channels of resistance arteries of the rat

En la arteria mesentérica anterior de la rata y sus ramas, perfundidas con una solución de Tyrode modificada, el efecto vasoconstrictor producido por la Noradrenalina (NA), Adrenalina (AD), Serotonina (ST) y Vasopresina (VP), se mantiene cuando el Ca2+ extracelular ha sido agotado por una perfusión privada de Ca2+, pero las respuestas son abolidas por La3+, EDTA, Verapamil y Nefedipina. Estas drogas desplazan el Ca fijado al plasmalena, que ingresa al citoplasma de la célula muscular lisa cuando el agonista se fija al receptor y de esta manera inhiben su efecto vascular. Cuando las arterias mesentéricas son perfundidas con una solución con Ca2+, es incrementar considerablemente la concentración vasoconstrictores de los agonistas. Estas drogas parecen competir con el Ca2+ extracelular por los lugares que éste ocupa en el plasmalema y que es responsable de iniciar el mecanismo vasoconstrictor cuando los agonistas se fijan a sus recpetores. El efecto vasoconstrictor del K es abolido cuando falta el Ca extracelular y también por los antagonistas cálcios en bajas concentraciones, que son insuficientes para anular la vasoconstricción inducida pro al NA, AD, ST y VP. El Ca fijado a los canales accionados por voltaje parece estar más debilmente fijado al plasmalema que el de los canales accionados por agonistas. Los efectos vasoconstrictores de la NA, AD, ST y VP, muestran diferente sensibilidad respecto a los antagonistas cálcicos, indicando que los canales cálcicos accionados por estos agonistas tienen ciertas diferencias estructurales que explican este comportamiento