钾通道开放剂降低血管平滑肌细胞内游离钙浓度(英文)

Potassium channel openers inhibit ATP-induced cytosolic free calcium increase in cultured rabbit aortic smooth muscle cells

目的:研究PCO—Pin,Nic,Lem及RP对VMSC内[Ca^(2+)]_i的改变及其可能机制。方法:VSMC加入Fura-2 AM 2.5μmol·L^(-1)37℃下孵育50min,[Ca^(2+)]_i用荧光分光光度计检测。结果:4种PCO能较弱地抑制K^+30 mmol·L^(-1)诱导的[Ca^(2+)]_i增加,但明显抑制ATP 0.1mmol·L^(-1)诱导的[Ca^(2+)]_i峰相及持续相增加,且呈剂量依赖性。格列苯脲完全阻断Pin,Lem及RP的作用,只部分抑制Nic的作用。无钙液中先给4种PCO,能显著抑制ATP诱导的[Ca^(2+)]_i峰相增加。结论:4种PCO均抑制ATP诱导的[Ca^(2+)]_i增加,此作用与减少细胞外钙内流及细胞内钙释放有关。

AIM: To study the effects of potassium channel openers (PCO) on cytosolic free calcium ([Ca ]i) changes and their possible mechanisms in vascular smooth muscle cells (VSMC). METHODS: Cultured rabbit aortic VSMC were treated with Fura-2 AM 2.5 μmol· L-1 at 37 $ for 50 min. The PCO were pinacidil (Pin), nicorandil (Nic), lemakalim (Lem), and RP 49356 (RP). [Ca2+ ]; level was measured by f luorospectrometer. RESULTS: [Ca2+ ]; increase induced by K± 30 rnmol·L-1 was weakly inhibited by Pin, Nic, Lem, and RP (441 ± 23, 455 ± 48, 451 ± 22, 370 ± 31 vs 544 ± 40 nmol·L-1, P<0.01). ATP (0.1 mmol · L-1)-induced peak and sustained [ Ca2 + ]; increase were inhibited by these agents in a concentration-dependent manner. The effects of Pin, Lem, and RP were completely canceled (peak phase: 549 ± 39, 540 ± 30, 564 ± 13 vs 541 ± 39 nmol· L-1; sustained phase: 413 ± 25, 364 ± 16, 377 ± 11 vs 380 ±8 nmol·L-1), but that of Nic was only partially blocked (peak phase: 453 ± 31 vs 541 nmol· L-1; sustained phase: 348 ± 19 vs 380 ± 8 nmol· L-1, P <0.01) by glibenclamide (Gli, 10 μmol·L-1). Pretreated with the Pin, Nic, Lem, and RP (10 μmol·L-1 ), the peak [Ca + ]; elevation induced by ATP was reduced in the Ca2±-free solution (129 ± 17, 142 ± 21, 136 ± 14, 114 ± 9 vs 258 ± 32 nmol ·L-1,P<0.01) CONCLUSION: pin, Nic, Lem, and RP inhibited ATP-induced [ Ca2+ ]; increase, associated with decreases of both Ca2 + release from intracellular store and Ca2+ influx from extracellular store.