Cl~-通道阻断剂对5-HT和CPA引起的兔脑椎基底动脉平滑肌细胞Ca~(2+)内流的影响

目的　在培养的兔脑椎基底动脉平滑肌细胞上观察5 HT和CPA诱导的Ca2 + 内流的特性 ,电压依赖性Ca2 + 通道 (VDC)抑制药尼莫地平 ,非电压依赖性Ca2 + 通道抑制药SK&F963 65及Cl-通道阻断剂DIDS、NPPB对两种激动剂引起 Ca2 + ]i 反应的影响 ,以探讨脑血管平滑肌细胞中 5 HT引起Ca2 + 内流的特性、Cl-通道与Ca2 + 内流的关系。方法　采用生物荧光双波长影像分析系统瞬即测定单细胞胞质Ca2 + ]i 技术。结果　① 5 HT和CPA均能诱导平滑肌细胞Ca2 + ]i 呈双相升高 ,并且 5 HT诱导的Ca2 + 释放是环匹阿尼酸 (CPA)敏感Ca2 + 池的一部分 ;②尼莫地平对 5 HT和CPA触发的Ca2 + 内流无明显影响 ,而SK&F963 65可阻止二者触发的Ca2 + 内流 ;③Cl-通道阻断剂DIDS、NPPB呈浓度依赖性抑制Ca2 + 内流 ,在SK&F963 65最大限度抑制Ca2 + 内流后 ,DIDS、NPPB可进一步抑制Ca2 + 内流 ;而Ca2 +内流被DIDS、NPPB分别最大抑制后 ,SK&F963 65也可进一步抑制Ca2 + 内流。结论　 5 HT引起的Ca2 + 内流是经SK&F963 65敏感的非VDC ,其中包含Ca2 + 释放引起的Ca2 + 内流 (CRAC)成分与非CRAC成分 ,并且这两部分Ca2 +内流均与DIDS、NPPB敏感的Cl-通道开放有关

Effects of chloride channel blockers on 5-HT and CPA-induced Ca2+ influx in cultured rabbit basilar artery smooth muscle cells

AIM In order to understand the 5 HT induced Ca 2+ influx characterization and the relationship between chloride channels and the Ca 2+ influx, we studied the effects of Ca 2+ blockers(nimodipine and SK&F96365) and Cl -channel blockers(DIDS and NPPB) on 5 HT and cyclopiazonic acid(CPA) induced Ca 2+ influx in cultured rabbit basilar artery smooth muscle cells. METHODS We measured Ca 2+ ] i of cultured rabbit basilar artery smooth muscle cells growing on glass coverslips using ratiometric video fluorescence microscopy and the Ca 2+ sensitive dye, fura 2. RESULTS ①It was found that application of 5 HT and CPA gave rise to biphasic Ca 2+ ] i elevation.5 HT only triggered a fraction of CPA sensitive Ca 2+ store, which was enough to activate Ca 2+ entry; ②Nimodipine had no effect on both 5 HT and CPA induced Ca 2+ entry, while SK&F96365 inhibited them; ③DIDS and NPPB inhibited 5 HT and CPA induced Ca 2+ influx in a concentration dependent manner. Ca 2+ influx was further inhibited by DIDS or NPPB after the maximal inhibition by SK&F96365. SK&F96365 also further inhibited the Ca 2+ influx which had been inhibited by DIDS or NPPB. CONCLUSION These data suggest that 5 HT induced Ca 2+ influx in cultured rabbit basilar artery smooth muscle cells is related to non VDC, which includes CRAC and non CRAC parts, and DIDS or NPPB sensitive Cl -channel is related to this Ca 2+ influx.