血管紧张素Ⅱ对血管平滑肌细胞内游离钙的作用机制

MechanismofcytosolicfreecalciumchangescausedbyangiotensinⅡinvascularsmoothmusclecels

本研究用５７０型粘附式细胞仪（ＡＣＡＳ－５７０）动态观察了血管紧张素Ⅱ（ＡｎｇⅡ）对单个平滑肌细胞（ＳＭＣ）内游离钙的影响，探讨了ＡｎｇⅡ调节ＳＭＣ内游离钙的改变的机制。分离兔主动脉中层平滑肌，用含１０％小牛血清的ＤＭＥＭ培养，第３～５代细胞用于实验，并于实验前两天去除血清使细胞处于静止期。结果发现：ＡｎｇⅡ可引起细胞内一个快的、短暂的、剂量依赖性的游离钙升高，ＡｎｇⅡ的拮抗剂沙拉斯（ｓａｒａｌａｓｉｎ）可抑制这种作用，而钙离子通道阻滞剂硝苯地平或维拉帕米则没有影响。提示：ＡｎｇⅡ调节ＳＭＣ内游离钙升高的机制主要是通过促进细胞内贮存钙的释放。

Inordertoinvestigatethemechanismofcytosolicfreecalciumchangecausedbyan-giotensinⅡ(AngⅡ)invascularsmoothmusclecels(SMC),thecytosolicfreecalciuminsingleSMCwasdeterminedbyadhesivecelanalyzingandsortingcytometer(ACAS-570).RabbitmediaSMCswereisolatedfromaorticexplants.CelswerefedwithDelbecco′smodifiedessentialmedium(DMEM)supplementedwith10%fetalbovineserum(FBS).SMCsusedforexperimentswerebe-tweenpassages3and5andweredeprivedofserumfortwodayspriortousetomakethecelsquies-cent.ItwasfoundthatAngⅡcausedarapid,transientandconcentration-dependentincreasein[Ca2+]i,whichwasblockedbypreincubationofcelswithAngⅡreceptorantagonistsaralasin.NoefectsonAngⅡ-inducedincreasein[Ca2+]iwerefound,ifcelswerepretreatedwithcalcium-an-tagonists,nifedipineorverapamil.TheresultssuggestedthatAngⅡ-inducedalternationin[Ca2+]iaremainlytheresultofconsequentCa2+releaseintocytoplasmfromintracelularstoresratherthaninflowofextracelularCa2+.