Role of calcium mobilization in sodium nitroprusside-induced increase of calcium-activated potassium currents in gastric antral circular myocytes of guinea pig  

胞内钙动员在硝普钠增加豚鼠胃窦环行肌细胞钙激活钾电流中的作用(英文)

作　　者：禹永春[1] 郭慧淑[1] 李英 朴琳 李林 李在琉 许文燮 

机构地区：[1]延边大学医学院消化生理研究室

出　　处：《Acta Pharmacologica Sinica》2003年第8期93-99,113,共7页中国药理学报（英文版）

基　　金：Project supported by the National Natural Science Foundation of China, № 3966026.

摘　　要：AIM: To investigate the role of calcium mobilization in the calcium-activated potassium currents [I_K（ca）] increased by sodium nitroprusside （SNP）, a nitric oxide （NO） donor, in gastric antral circular myocytes of the guinea pig. METHODS: A perforated patch-clamp technique was used, and the myocytes were isolated by collagenase. RESULTS: SNP 100 μmol/L significantly increased I_K（ca）, and enhanced the spontaneous transient outward currents （STOC）. SNP-induced increase of I_K（Ca） was not blocked by extracellular calcium-free solution (containing egtazic acid 10 μmol/L and nicardipine 5 μmol/L, an L-type calcium channel blocker. And SNP 100 μmol/L suppressed the L-type calcium currents (I_Ca). SNP-induced increase of STOC was inhibited by heparin 3 g/L, a potent inhibitor of inositol triphosphate receptor （InsP₃R）. However, ryanodine 10 μmol/L, an inhibitor of calciuminduced calcium release （CICR）, did not inhibit the effect of SNP-induced increase of STOC. Methylene blue （1 μmol/L）, an inhibitor of soluble guanylate cyclase, also inhibited such an effect. CONCLUSION: The increase of I_K（Ca） caused by SNP may be mediated by cGMP via IP₃-sensitive calcium pools, however, extracellular Ca²⁺ may not be involved in the process.目的:研究胞内钙动员在硝普钠(SNP)增加豚鼠胃窦环行平滑肌细胞钙敏感性钾电流[I_((K(Ca))]中的作用。方法:采用传统全细胞膜片箝技术,并用胶原酶急性分离单细胞。用硝普钠作为一氧化氮供体。结果:SNP100 μmol/L明显增加钙敏感性钾电流,同时也可以显著地增加瞬间外向性钾电流(STOC)。SNP引发I_(K(Ca))增加效应不能被胞外无钙液(含依他酸10 μmol/L)和L-型钙通道阻断剂尼卡地平5 μmol/LL所阻断。SNP100 μmol/L可以明显地抑制钙电流。SNP引发STOC增加效应可以明显地被三磷酸肌醇受体特异性阻断剂肝素3 g/L所阻断,却不能被兰尼碱10 μmol/L所阻断。亚甲基蓝1 μmol/L,特异性胞内鸟苷酸环化酶抑制剂,也可以显著地抑制上述效应。结论:SNP引发钙敏感性钾电流的增加可能是胞内第二信使cGMP通过激活胞内三磷酸肌醇诱导的钙释放的途径而实现的,而胞外钙离子不参与这一过程。

关 键 词：sodium nitroprusside potassium channels CALCIUM stomach smooth muscle pyloric antrum NICARDIPINE HEPARIN RYANODINE patch-clamp techniques 

分 类 号：R9[医药卫生—药学]