埃他卡林对大鼠尾动脉平滑肌细胞［Ca2+］i， PKA和PKC活性的影响埃他卡林对大鼠尾动脉平滑肌细胞［Ca2+］i， PKA和PKC活性的影响

细胞内钙参与了对几乎所有类型细胞的各种生理活动的调节[1],并通过影响PKA和PKC等大分子蛋白,进一步调控细胞的分裂和增殖。以ATP敏感型钾通道(KATP)为靶点的钾通道开放剂(KCO)是一类新型的抗高血压药物[2,3]。KCO激活血管平滑肌KATP,间接抑制钙通道的开放,从而使[Ca2 ]i降低,

Effects of iptakalim on intracellular calcium concentrations, PKA and PKC activities in rat tail artery smooth muscle cells

AIM: To investigate the effects of iptakalim, a new structural potassium channel opener (KCO), on intracellular calcium concentration ([Ca2+]i), protein kinase C (PKC), and cAMP-dependent kinase (PKA) activities in rat tail artery smooth muscle cells (RTA-SMC), and to analyze mechanisms involved in iptakalim reversing hypertensive vascular remodeling. METHODS: RTA-SMC was cultured and passages 3-4 were used for experiment. [Ca2+] i was measured by laser scanning confocal microscope after loaded with fluorescent indicator fluo-3-acetoxymethylester, and activities of PKA and PKC were detected by commercial assay kits (the nonradioactive PepTag system) following instructions. RESULTS: Compared with baseline, [Ca2+] i reduced significantly after iptakalim- or pinacidil-treatment at concentrations of 0.1, 1 and 10 micromol x L(-1), while diazoxide caused significant decrease at concentration of 1 and 10 micromol x L(-1). After preincubation with 1 micromol x L(-1) glibenclamide, [Ca2+] i was not significantly changed when iptakalim, pinacidil or diazoxide were added at concentration of 0.1 and 1 micromol x L(-1). Activities of PKA and PKC increased significantly by 1 micromol x L(-1) iptakalim- or pinacidil-treatment, while 1 micromol x L(-1) diazoxide induced significant change in activity of PKC but not in that of PKA. CONCLUSION: The characteristics of iptakalim on [Ca2+] i, PKA and PKC are more or less similar to those of pinacidil. Iptakalim decreased [Ca2+] i while increased PKA and PKC activities of RTA-SMCs, which may contribute to its ability to reverse antihypertensive vascular remodeling.