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Resumo Fundamento A hipertensão arterial sistêmica é um fator de risco para disfunções cardíacas, renais e metabólicas. A busca por novas estratégias para prevenir e tratar doenças cardiovasculares levou à síntese de novas N-acilidrazonas para produzir efeito anti-hipertensivo. Os receptores de adenosina são um alvo alternativo para reduzir a pressão arterial devido à sua ação vasodilatadora e propriedades antioxidantes, que podem reduzir o estresse oxidativo característico da hipertensão arterial sistêmica. Objetivo Avaliar o perfil anti-hipertensivo de novos compostos contendo selênio desenvolvidos para melhorar sua interação com os receptores de adenosina. Métodos Foi avaliada a reatividade vascular, registrando-se a tensão isométrica da aorta torácica pré-contraída de ratos Wistar machos após exposição a concentrações crescentes de cada derivado (0,1 a 100 μM). Para investigar o efeito anti-hipertensivo em ratos espontaneamente hipertensos, foram determinadas a pressão arterial sistólica, pressão arterial diastólica, pressão arterial média e a frequência cardíaca após administração intravenosa de 10 e 30 μmol/kg do composto selecionado LASSBio-2062. Resultados Os compostos denominados LASSBio-2062, LASSBio-2063, LASSBio-2075, LASSBio-2076, LASSBio-2084, LASSBio-430, LASSBio-2092 e LASSBio-2093 promoveram vasodilatação com concentrações efetivas médias de 15,5 ± 6,5; 14,6 ± 2,9; 18,7 ± 9,6; 6,7 ± 4,1; > 100; 6,0 ± 3,6; 37,8 ± 11,8; e 15,9 ± 5,7 μM, respectivamente. O LASSBio-2062 (30 μmol/kg) reduziu a pressão arterial média em ratos espontaneamente hipertensos de 124,6 ± 8,6 para 72,0 ± 12,3 mmHg (p < 0,05). A ativação do receptor de adenosina subtipo A3 e dos canais de potássio parece estar envolvida no efeito anti-hipertensivo do LASSBio-2062. Conclusões O novo agonista do receptor de adenosina e ativador dos canais de potássio é um potencial agente terapêutico para o tratamento da hipertensão arterial sistêmica.
Abstract Background Systemic arterial hypertension is a risk factor for cardiac, renal, and metabolic dysfunction. The search for new strategies to prevent and treat cardiovascular diseases led to the synthesis of new N-acylhydrazones to produce antihypertensive effect. Adenosine receptors are an alternative target to reduce blood pressure because of their vasodilatory action and antioxidant properties, which may reduce oxidative stress characteristic of systemic arterial hypertension. Objective To evaluate the antihypertensive profile of novel selenium-containing compounds designed to improve their interaction with adenosine receptors. Methods Vascular reactivity was evaluated by recording the isometric tension of pre-contracted thoracic aorta of male Wistar rats after exposure to increasing concentrations of each derivative (0.1 to 100 μM). To investigate the antihypertensive effect in spontaneously hypertensive rats, systolic, diastolic, and mean arterial pressure and heart rate were determined after intravenous administration of 10 and 30 μmol/kg of the selected compound LASSBio-2062. Results Compounds named LASSBio-2062, LASSBio-2063, LASSBio-2075, LASSBio-2076, LASSBio-2084, LASSBio-430, LASSBio-2092, and LASSBio-2093 promoted vasodilation with mean effective concentrations of 15.5 ± 6.5; 14.6 ± 2.9; 18.7 ± 9.6; 6.7 ± 4.1; > 100; 6.0 ± 3.6; 37.8 ± 11.8; and 15.9 ± 5.7 μM, respectively. LASSBio-2062 (30 μmol/kg) reduced mean arterial pressure in spontaneously hypertensive rats from 124.6 ± 8.6 to 72.0 ± 12.3 mmHg (p < 0.05). Activation of adenosine receptor subtype A3 and potassium channels seem to be involved in the antihypertensive effect of LASSBio-2062. Conclusions The new agonist of adenosine receptor and activator of potassium channels is a potential therapeutic agent to treat systemic arterial hypertension.
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La hipertensión arterial pulmonar se caracteriza por una presión arterial pulmonar media y resistencia vascular pulmonar elevadas y remodelado patológico de las arterias pulmonares. La entrada de calcio desde el espacio extracelular al intracelular a través de canales dependientes e independientes de voltaje juega un rol fundamental en el aumento de la contractilidad de las arterias pulmonares y la pérdida de regulación del comportamiento proliferativo de las células de las distintas capas de la pared de las arterias pulmonares. De esta manera, estos canales contribuyen con la vasoconstricción exacerbada de las arterias pulmonares y a su remodelado patológico. El objetivo de esta revisión es recapitular la evidencia obtenida desde modelos celulares y animales respecto a la contribución de los principales canales de calcio de membrana plasmática en estos mecanismos fisiopatológicos claves en el desarrollo de la hipertensión pulmonar, discutiendo su valor potencial como diana farmacológica para terapias presentes y futuras.
Pulmonary arterial hypertension is characterized by increased mean pulmonary arterial pressure, resistance, and pathological remodeling of pulmonary arteries. Calcium entry from the extracellular to the intracellular space through voltage-dependent and -independent channels play a major role in the increase of contractility of pulmonary arteries and in the loss of regulation of the proliferative behavior of the cells from the different layers of the pulmonary arterial wall. In doing so, these channels contribute to enhanced vasoconstriction of pulmonary arteries and their pathological remodeling. This review aims to summarize the evidence obtained from animal and cellular models regarding the involvement of the main plasma membrane calcium channels in these key pathophysiological processes for pulmonary arterial hypertension, discussing the potential value as pharmacological targets for therapies in the present and the future.
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Objective:To evaluate the relationship between mitochondrial calcium uniporter protein (MCU)-mediated mitochondrial dynamics and intestinal ischemia-reperfusion (I/R) injury in mice.Methods:Twenty-four wild-type adult male C57BL/6J mice, aged 6-8 weeks, weighing 18-20 g, were divided into 4 groups ( n=6 each) using a random number table method: sham operation group (S group), intestinal I/R group (IIR group), sham operation+ MCU inhibitor Ru360 group (S+ Ru360 group) and intestinal I/R + Ru360 group (IIR+ Ru360 group). The mouse model of intestinal I/R injury was prepared by clamping the root of the superior mesenteric artery for 45 min followed by 2 h of reperfusion in anesthetized animals. Small intestinal tissues were obtained at the end of reperfusion for examination of the intestinal mucosal injury which was scored according to Chiu and for determination of the content of malondialdehyde (MDA) (TBA method), activity of superoxide dismutase (SOD) (WST-8 method), content of lactic dehydrogenase (LDH) (colorimetric method), and expression of MCU, dynamin-related protein 1 (Drp1), recombinant human mitochondrial fission 1 protein (Fis1), mitofusin-1 (Mfn1) and Mfn2 (by Western blot). Results:Compared with S and S+ Ru360 groups, the Chiu′s score and contents of MDA and LDH were significantly increased, the activity of SOD was decreased, the expression of MCU, Drp1 and Fis1 was up-regulated, and the expression of Mfn1 and Mfn2 was down-regulated in IIR and IIR+ Ru360 groups ( P<0.05). Compared with IIR group, the Chiu′s score and contents of MDA and LDH were significantly decreased, the activity of SOD was increased, the expression of MCU, Drp1 and Fis1 was down-regulated, and the expression of Mfn1 and Mfn2 was up-regulated in IIR+ Ru360 group ( P<0.05). Conclusions:The mechanism underlying intestinal I/R injury may be related to MCU-induced promotion of mitochondrial fission, reduction of mitochondrial fusion and mediation of imbalance in mitochondrial dynamics in mice.
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OBJECTIVE@#To investigate the effect of ferulic acid, a natural compound, on pancreatic beta cell viability, Ca2+ channels, and insulin secretion.@*METHODS@#We studied the effects of ferulic acid on rat insulinoma cell line viability using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide viability assay. The whole-cell patch-clamp technique and enzyme-linked immunosorbent assay were also used to examine the action of ferulic acid on Ca2+ channels and insulin secretion, respectively.@*RESULTS@#Ferulic acid did not affect cell viability during exposures up to 72 h. The electrophysiological study demonstrated that ferulic acid rapidly and concentration-dependently increased L-type Ca2+ channel current, shifting its activation curve in the hyperpolarizing direction with a decreased slope factor, while the voltage dependence of inactivation was not affected. On the other hand, ferulic acid have no effect on T-type Ca2+ channels. Furthermore, ferulic acid significantly increased insulin secretion, an effect inhibited by nifedipine and Ca2+-free extracellular fluid, confirming that ferulic acid-induced insulin secretion in these cells was mediated by augmenting Ca2+ influx through L-type Ca2+ channel. Our data also suggest that this may be a direct, nongenomic action.@*CONCLUSION@#This is the first electrophysiological demonstration that acute ferulic acid treatment could increase L-type Ca2+ channel current in pancreatic β cells by enhancing its voltage dependence of activation, leading to insulin secretion.
Subject(s)
Rats , Animals , Insulin Secretion , Insulin/pharmacology , Insulin-Secreting Cells/metabolism , Coumaric Acids/metabolism , Calcium/metabolismABSTRACT
Phα1ß is a neurotoxin purified from spider venom that acts as a high-voltage-activated (HVA) calcium channel blocker. This spider peptide has shown a high selectivity for N-type HVA calcium channels (NVACC) and an analgesic effect in several animal models of pain. Its activity was associated with a reduction in calcium transients, glutamate release, and reactive oxygen species production from the spinal cord tissue and dorsal ganglia root (DRG) in rats and mice. It has been reported that intrathecal (i.t.) administration of Phα1ß to treat chronic pain reverted opioid tolerance with a safer profile than ω-conotoxin MVIIA, a highly selective NVACC blocker. Following a recent development of recombinant Phα1ß (CTK 01512-2), a new molecular target, TRPA1, the structural arrangement of disulphide bridges, and an effect on glial plasticity have been identified. CTK 01512-2 reproduced the antinociceptive effects of the native toxin not only after the intrathecal but also after the intravenous administration. Herein, we review the Phα1ß antinociceptive activity in the most relevant pain models and its mechanisms of action, highlighting the impact of CTK 01512-2 synthesis and its potential for multimodal analgesia.
Subject(s)
Analgesics/adverse effects , Pain , Reactive Oxygen Species , Neurotoxins/isolation & purification , Peptides/isolation & purificationABSTRACT
Abstract Ph1 is a neurotoxin purified from spider venom that acts as a high-voltage-activated (HVA) calcium channel blocker. This spider peptide has shown a high selectivity for N-type HVA calcium channels (NVACC) and an analgesic effect in several animal models of pain. Its activity was associated with a reduction in calcium transients, glutamate release, and reactive oxygen species production from the spinal cord tissue and dorsal ganglia root (DRG) in rats and mice. It has been reported that intrathecal (i.t.) administration of Ph1 to treat chronic pain reverted opioid tolerance with a safer profile than -conotoxin MVIIA, a highly selective NVACC blocker. Following a recent development of recombinant Ph1 (CTK 01512-2), a new molecular target, TRPA1, the structural arrangement of disulphide bridges, and an effect on glial plasticity have been identified. CTK 01512-2 reproduced the antinociceptive effects of the native toxin not only after the intrathecal but also after the intravenous administration. Herein, we review the Ph1 antinociceptive activity in the most relevant pain models and its mechanisms of action, highlighting the impact of CTK 01512-2 synthesis and its potential for multimodal analgesia.
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Phα1ß is a neurotoxin purified from spider venom that acts as a high-voltage-activated (HVA) calcium channel blocker. This spider peptide has shown a high selectivity for N-type HVA calcium channels (NVACC) and an analgesic effect in several animal models of pain. Its activity was associated with a reduction in calcium transients, glutamate release, and reactive oxygen species production from the spinal cord tissue and dorsal ganglia root (DRG) in rats and mice. It has been reported that intrathecal (i.t.) administration of Phα1ß to treat chronic pain reverted opioid tolerance with a safer profile than ω-conotoxin MVIIA, a highly selective NVACC blocker. Following a recent development of recombinant Phα1ß (CTK 01512-2), a new molecular target, TRPA1, the structural arrangement of disulphide bridges, and an effect on glial plasticity have been identified. CTK 01512-2 reproduced the antinociceptive effects of the native toxin not only after the intrathecal but also after the intravenous administration. Herein, we review the Phα1ß antinociceptive activity in the most relevant pain models and its mechanisms of action, highlighting the impact of CTK 01512-2 synthesis and its potential for multimodal analgesia.
Subject(s)
Pain , Peptides/isolation & purification , Reactive Oxygen Species , Analgesics/adverse effects , Neurotoxins/isolation & purificationABSTRACT
Despite extensive characterization of sex differences in the medial preoptic area (mPOA) of the hypothalamus, we know surprisingly little about whether or how male and female mPOA neurons differ electrophysiologically, especially in terms of neuronal firing and behavioral pattern generation. In this study, by performing whole-cell patch clamp recordings of the mPOA, we investigated the influences of sex, cell type, and gonadal hormones on the electrophysiological properties of mPOA neurons. Notably, we uncovered significant sex differences in input resistance (male > female) and in the percentage of neurons that displayed post-inhibitory rebound (male > female). Furthermore, we found that the current mediated by the T-type Ca
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In most non-excited cells, voltage-gated T-type calcium channels present three properties of activation, inactivation and slow inactivation, thus contribute to cellular calcium signaling and membrane potential. By which T-type calcium channels play an important role in many cancer cellular processes such as cell proliferation, differentiation, apoptosis, invasion, and metastasis. Inhibiting T-type calcium channels by drugs or genetic tools can change the related cellular currents and the intracellular Ca 2+ , thereby regulating the biological tumorigenesis. This article reviews the electrophysiological of T-type calcium channels during tumor progression, aims to provide a scientific basis for the study and treatment in cancer.
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Introduction:Obesity is closely associated with various types of illness, primarily caused by more calorie intake than body burn. In adipocytes, Calcium (Ca2+) is an important second messenger involved in theregulation of many physiological functions which are essential for survival. In the present research, we have investigated the role of Ca2+ions in obesity by manipulating cytosolic Ca2+ion concentration by selective blocking/advancing the Ca2+ions through the voltage-gated calcium channels. Voltage-gated calcium channel (vCa) plays a key role in regulating intracellular and extracellular Ca2+concentration.Cytoplasmic level of Ca2+was manipulated by supplying calcium carbonateand by using vCa blockers i.e. nifedipine-(N-type-vCa-CCB) and ethosuximide (T-type, vCa-CCB).Methods:Obesity was induced by progesterone in female mice and test drugs were co-administered with progesterone whereas sibutramine was used as standard. The treatment was carried out for 28 days, during and afterthetreatment periodvarious parameters were studied viz food consumption, change in body weight and temperature, the effect on WAT (white adipose tissue, adiposity index, histology of fat pad) and fecal lipid content.Results:Calcium carbonate treated group has shown promising effects in the decrease in body weight by increasing fecal lipid content and lipolysis which was reflected by an increase in body temperature. Ethosuximide also offered significant protection by decreasing the food intake but has not shown any notable effect on fecal fat content, whereas nifedipine has not offered any protection against the obesity induced by neurosteroid.Conclusion:Calcium carbonate has significant anti-obesity activity by including thermogenesis, and increasing fecal lipid content
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Aims: We aimed in this study to investigate the mechanisms of the vasorelaxation effect caused by the anthocyanins-enriched extract of Odontonema strictum flowers. Study Design: Anthocyanins-enriched extract of Odontonema strictum flowers and vasorelaxantes activities of mice aortic rings. Place and Duration of Study: The flowers of Odontonema strictum (Nees) Kuntze (Acanthaceae) were collected in January 2015 at the “Institut de Recherche en Sciences de la Santé (IRSS)” experimental station in Ouagadougou. The experiments were conducted in October - November 2018 at the department of Medicine and Traditional Pharmacopeia-Pharmacy (MEPHATRA-PH)/IRSS. Methodology: The extract was enriched in anthocyanins using Amberlite XAD-7 non-ionic resin column. The vasorelaxant activity of anthocyanins-enriched extract of O. strictum flowers (OSF) was tested using isolated organ-chamber technique with mice aorta rings. Results: OSF showed concentration-dependent relaxant effects on mice endothelium intact or denuded aortic rings pre-contracted with U46619 (10-7 M) and KCl (80 mM). OSF induced relaxation in the mice aortic rings by stimulating smooth muscle cells. The vasorelaxant effect of OSF (10-1000 µg/mL) was similar in endothelium-intact and endothelium-denuded aortic rings. The maximum relaxant effect was 93.78 ± 4.69% and 92.30 ± 3.19% for endothelium-intact and endothelium-denuded aortic rings, respectively. Moreover, after incubation of the aorta rings with OSF (400 µg/mL) or vehicle (0.02% of DMSO) in PSS, OSF blocked the contraction through mechanism involving inhibition of CaCl2 and U46619 effect. Conclusions: The present study provides a pharmacological evidence for the antihypertensive medicinal use of Odontonema strictum by highlighting its vasorelaxant activity.
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A lesão inflamatória de origem periférica aumenta a sensibilidade sensória a um estímulo mecânico de leve intensidade, provocando dor, um processo conhecido como alodinia. A recente descoberta de que astrócitos e micróglia da medula espinal tornam-se reativos devido à inflamação periférica, sugere que a glia deve estar envolvida na manifestação patológica da dor. Nesta tese, observou-se que a inflamação periférica, induzida pela injeção intraplantar do adjuvante completo de Freund (CFA), causa alodinia mecânica assim como mudanças na glia. Dentre essas mudanças destacamos o aumento de marcadores específicos da glia, aumento da proliferação de astrócitos assim como alterações morfológicas na micróglia, todas elas características do fenótipo reativo da glia. Além disso, este estudo descobriu que a injeção intratecal da toxina de aranha Phα1ß, um peptídeo com ação analgésica que bloqueia canais de cálcio dependente de voltagem (VGCC), reverte todas as alterações da glia da medula espinal causadas pela inflamação periférica. Essas observações, em resumo, sugerem que a toxina Phα1ß, além de sua já reconhecida ação analgésica, também possui efeitos anti-inflamatórios sobre a plasticidade glial.
A peripheral inflammatory injury increases the mechanical sensitivity in response to light-touch, also named as allodynia. The discovery that spinal astrocytes and microglia become reactive to the peripheral inflammation suggests that the glia presumably engage with the pain pathophysiology. Here, we found that the peripheral inflammation induced by intraplantar injection of complete Freund's adjuvant (CFA) produce mechanical allodynia and robust changes in the spinal glial. Among these changes we found an increase of specific glial markers, increment of astrocytes proliferation, elevation of microglia density and morphologic changes, all of them compatible with the glia reactive phenotype. Moreover, we found that intrathecal injection with the analgesic Phα1ß spider toxin, a voltage-gated calcium channel (VGCC) blocker, reverses all the glial pathological features of the peripheral inflammation. We therefore suggest that the Phα1ß toxin, apart from its notable analgesic effects, is also a potent anti-inflammatory compound acting on glial plasticity.
Subject(s)
Spider Venoms , Neuroglia , Pain Management , Analgesics , Pain , Hyperalgesia , InflammationABSTRACT
Docosahexaenoic acid (DHA), an omega-3-fatty acid, modulates multiple cellular functions. In this study, we addressed the effects of DHA on human umbilical vein endothelial cell calcium transient and endothelial nitric oxide synthase (eNOS) phosphorylation under control and adenosine triphosphate (ATP, 100 µM) stimulated conditions. Cells were treated for 48 h with DHA concentrations from 3 to 50 µM. Calcium transient was measured using the fluorescent dye Fura-2-AM and eNOS phosphorylation was addressed by western blot. DHA dose-dependently reduced the ATP stimulated Ca²⁺-transient. This effect was preserved in the presence of BAPTA (10 and 20 µM) which chelated the intracellular calcium, but eliminated after withdrawal of extracellular calcium, application of 2-aminoethoxy-diphenylborane (75 µM) to inhibit store-operated calcium channel or thapsigargin (2 µM) to delete calcium store. In addition, DHA (12 µM) increased ser1177/thr495 phosphorylation of eNOS under baseline conditions but had no significant effect on this ratio under conditions of ATP stimulation. In conclusion, DHA dose-dependently inhibited the ATP-induced calcium transient, probably via store-operated calcium channels. Furthermore, DHA changed eNOS phosphorylation suggesting activation of the enzyme. Hence, DHA may shift the regulation of eNOS away from a Ca²⁺ activated mode to a preferentially controlled phosphorylation mode.
Subject(s)
Humans , Adenosine Triphosphate , Adenosine , Blotting, Western , Calcium Channels , Calcium , Endothelial Cells , Nitric Oxide Synthase Type III , Phosphorylation , Thapsigargin , Umbilical VeinsABSTRACT
Background: Obesity is associated with many functional gastrointestinal disorders, such as gastrointestinal motility disorder. Previous studies showed that adipose tissue-derived adipokine visfatin (VF), which increased in obesity, might impair myometrial contractility and cause vascular smooth muscle relaxation. Aims: To investigate the effect of VF on contractility of colonic smooth muscle in rats and its underlying mechanism. Methods: Segments of distal colon from normal Sprague-Dawley (SD) rats were dissected into strips (0.3 cm × 0.8 cm), and the effect of VF on contractility of muscle strips was measured by biological signal collection system. In in vitro study, colonic smooth muscle cells (SMCs) from neonatal SD rats were cultured and treated with VF; phosphorylation of myoglobulin light chain (MLC) and expression of calcium channel protein Cav1.2 (α1 subunit) were assessed by Western blotting. Cultured in buffer solution with or without calcium, the acetylcholine-stimulated intracellular Ca2+ level in SMCs was detected by confocal laser scanning microscopy. Results: In muscle strip contractility assay, VF (200 ng/mL) significantly inhibited the contractility of colonic smooth muscle strip from normal adult rats (P<0.05). In cultured colonic SMCs, VF (200 ng/mL) down-regulated the calcium channel protein Cav1.2 expression and reduced the intracellular Ca2+ level and MLC phosphorylation (P<0.05). Conclusions: VF may down-regulate the expression of calcium channel protein Cav1.2 on the membrane of colonic SMCs and cause colonic dysmotility by interfering with Ca2+ signaling and smooth muscle contractility.
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Irritable bowel syndrome (IBS) is a common functional gastrointestinal disorder, mainly manifested as recurrent abdominal pain, abdominal discomfort and/or changes of defecation habits and stool character, its pathogenesis has not been fully clarified. The pathophysiology is characterized by visceral hypersensitivity, abnormal intestinal motility, and so on. Abnormality of ion channels may be in involved in the pathophysiological mechanism of IBS. This article reviewed the progress in study on ion channels and pathogenesis of IBS.
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Objective: To evaluate spasmolytic mechanisms of aqueous and methanolic extracts from Distemonanthus benthamianus trunk-bark. Methods: Spasmolytic activities of extracts were evaluated in vitro on spontaneous and potassium chloride-induced jejunum contractions, or against cholinergic [acetylcholine (0.3μmol/L)] stimulations. High performance liquid chromatography analysis of both extracts was performed in reference to standard compounds. Results: Extracts developed concentration-dependent inhibitory activities. The methanolic extract, which revealed better activity, produced spasmolytic and myorelaxant effects at concentrations of 0.01-0.30 mg/mL with EC50 of 0.06 and 0.09 mg/mL (95％ CI: 0.03-0.3 mg/mL), respectively. Its anticholinergic effect was obtained at the same concentrations with EC50 of 0.11 mg/mL (95％ CI:0.03-0.3 mg/mL). Chromatograms showed the presence of gallic acid in both extracts, rutin being only detected in the aqueous extract. Conclusions: Distemonanthus benthamianus extracts exhibit verapamil and atropine-like activities, thus highlighting calcium channels and muscarinic receptors blocking potentials, which may be conveyed by some phenolic compounds. These results confirm the antidiarrheal activity of Distemonanthus benthamianus extracts.
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:Vascular endothelial cells are the barrier of blood vessels .Endothelial injury will lead to occurrence of multiple diseases ,whose mechanism is related to intracellular calcium signal pool regulation .Ca2+ is a secondary messenger for information delivery inside and outside cells ,it initiates endothelial cell signals and plays an important role in controlling vascular tension and endothelial permeability .Study on mechanism of vascular endothelial cell in‐jury has become a hot topic in recent years ,and calcium homeostasis imbalance is the key factor ,whose mechanism is still not clear .The present article reviewed regulating mechanisms of vascular endothelial cytoplasmic membrane calcium transport and intracellular calcium pool regulation , aimed at providing new thinking for prevention and treatment of calcium regulation related diseases .
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Objective@#To investigate the impact of n-3 polyunsaturated fatty acid (n-3 PUFA) on function and expression of store-operated calcium channels (SOCC) in coronary artery smooth muscle cells (SMC) derived from diabetic rat.@*Methods@#A total of 180 healthy male Sprague-Dawley (SD) rats were randomly divided into normal group (N, n=45), placebo-treated diabetic group (D, n=45), lose dose n-3 PUFA treated diabetic group (DL, n=45) and high dose n-3 PUFAs treated diabetic group (DH, n=45). Streptozotocin-induced diabetic rat animal model was established by two consecutive intraperitoneal injections. After modeling, rats in group DL and DH were treated with 10 mg·kg-1·d-1 and 50 mg·kg-1·d-1 n-3 PUFAs respectively per gavage for eight weeks. After eight weeks, rat coronary artery SMC was isolated by enzyme digestion. Changes of cytosolic calcium concentration in coronary artery SMC were examined by calcium fluorescence imaging technique, coronary artery tension was detected by myograph system, and protein expressions of SOCC on coronary artery SMC were measured by Western blot.@*Results@#SOCC induced ΔF340/F380 of group N, D, DL and DH were 0.425±0.023, 0.838±0.037, 0.342±0.052 and 0.364±0.045 respectively, which was significantly lower in group N, DL, DH than in group D (P<0.05). SOCC induced changes of tensions were 0.94±0.09, 1.95±0.18, 1.35±0.24 and 1.01±0.18 in the group N, D, DL and DH, respectively, which was significantly lower in group N and DH than in group D (P<0.05). Protein expressions of STIM1, Orai1 and TRPC1 were significantly higher in diabetic rat coronary SMC than in group N (P<0.05). STIM1 protein expressions were significantly lower in group DL and DH than in group D, and Orai1 and TRPC1 protein expressions were similar among group.@*Conclusions@#Coronary artery tension, cytosolic calcium concentration and protein expressions of SOCC are higher in diabetic rat coronary artery SMC when compared with normal rats. n-3 PUFA intervention could downregulate the protein expression of SOCC, reduce cytosolic calcium concentration and coronary artery tension, and is protective to the diabetic injury in coronary artery.
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Objective@#To investigate the effects and mechanism of digoxin on atrium electrical remodeling and susceptibility of atrial fibrillation (AF) in aged rabbits.@*Methods@#Twenty aged male New Zealand rabbits were divided into aged group and aged plus digoxin group (n=10 each). Electrical parameters including heart rate (HR), RR and QT interval, ST segment and P wave dispersion from normal Ⅱ electrocardiogram, and the maximum upstroke velocity (Maxdv/dt), plateau potential (plateau P), action potential duration of 10%, 20% and 90% (APD10, APD20, APD90) from recording of monophasic action potential (MAP), as well as atrial effective refractory period (AERP200) and dispersion (dERP200) with 200 ms of basic cycle length (BCL), and frequency self adaptation of AERP with 300 ms and 150 ms of BCLs (fERP) were recorded and compared between the 2 groups. BCLs and inducibility of AF post programmed electrical stimulation and Burst-pacing in left atrium tissue of rabbits in vivo were also analyzed. The L-type calcium current (ICa-L) in 2 groups were recorded via whole-cell patch clamp technique, and the fluorescence intensity of intracellular free Ca2+ was detected with Flup-3/AM loading by the laser scanning confocal microscope in enzymatically dissociated single rabbit atrial myocytes.@*Results@#Compared with aged group, the heart rate was faster, RR and QT interval were obvious shorter, ST segment was raised and P wave dispersion was significantly increased in aged plus digoxin group (all P<0.05). Moreover, compared with aged group, the Maxdv/dt and plateau P were obviously increased, APD10 and APD20 were significantly prolongated, and APD90 was significantly shorter in aged plus digoxin group (all P<0.01). Otherwise, the fERP was markedly increased (0.81±0.15 vs. 0.67±0.05), and the induced rate of AF was obviously higher in aged plus digoxin group than in aged group (6/8 vs. 4/9) (all P<0.01). With voltage clamp model, digoxin significantly increased ICa-L of atrial myocytes of aged rabbits, When command potential was 10 mV, the current densities of ICa-L were significantly higher in digoxin group than that in aged group ((15.45±2.38) pA/pF vs. (7.03±1.69) pA/pF, P<0.01). Otherwise, the I-V curve of ICa-L was downward shifted of all I-V curves in digoxin perfused aged atrial cells of rabbits. Moreover, the fluorescence intensities of intracellular free Ca2+ was significantly higher in aged plus digoxin group than in aged group ((1 748±173) μmol/L vs. (478.13±87.63) μmol/L, P<0.01).@*Conclusion@#Digoxin could aggravate the atrial electrical remodeling in atrium of aged rabbits, facilitate susceptibility of atrial fibrillation in aged rabbit, increased current density of ICa-L and concentration of intracellular free Ca2+, followed Ca2+ overload and oscillations might be part of the underlying mechanisms.