川芎嗪对小动脉平滑肌细胞离子通道内向电流的作用

本文旨在用Patch clamp技术研究川芎嗪(Ligustrazine)对小动脉平滑肌细胞膜离子单通道的内向电流的作用。取Wistar大鼠(雄性,体重200～300克)的肠系膜小动脉(口径50μ左右),经酶法分离制备成单个平滑肌细胞。实验时置细胞于盛有溶液的小池中。池内液成份为(浓度mM):NaCl 125;MgCl_2 1.2;NaH_2PO_4 1.2;HEPES 10;     

平滑肌细胞膜的钙激活Cl~-通道

在多种平滑肌上都已发现Ｃａ２＋激活Ｃｌ－通道。胞内游离钙升高是钙激活氯通道的必要条件。多种刺激剂诱导胞内钙库释放钙而同时激活钾通道［ＩＫ（Ｃａ）］和氯通道［ＩＣｌ（Ｃａ）］。平滑肌细胞上激活ＩＣｌ（Ｃａ）的［Ｃａ２＋］ｉ阈值因动物种属和组织差异而不同。用荧光指示剂直接测定大鼠门静脉平滑肌细胞上的［Ｃａ２＋］ｉ得出激活ＩＫ（Ｃａ）的最小［Ｃａ２＋］ｉ应大于７０～８０μｍｏｌ·Ｌ－１,比激活ＩＣｌ（Ｃａ）的最低浓度１８０μｍｏｌ·Ｌ－１要小,因此认为ＩＫ（Ｃａ）要比ＩＣｌ（Ｃａ）对［Ｃａ２＋］ｉ更敏感。胞外钙通过电压依赖性钙通道进入胞内,［Ｃａ２＋］ｉ升高也能激活氯通道。Ｇ蛋白与某些受体偶联激活胞内第二信使ＩＰ３而激活氯通道。钙激活氯通道的电导很小,从全细胞电流分析应小于１０ｐＳ。平滑肌细胞上的氯平衡电位（ＥＣｌ）正于静息膜电位,因此Ｃｌ－通道开放Ｃｌ－外流驱动膜电位向ＥＣｌ方向靠近,形成膜的去极化。Ｃａ２＋激活Ｃｌ－通道开放使细胞膜去极化并引起细胞的兴奋,这种通道在由激素或神经递质引起平滑肌细胞的兴奋过程中起重要作用。     

NITRIC OXIDE INHIBITS A RISE OF ATP-INTRODUCEDCYTOSOLIC FREE Ca^2＋ CONCENTRATION AND RELEASE FROM INTRACELLULAR STORED Ca^2＋

Object. The effects of ATP-introduced a rise in cytosolic free Ca^2 concentration and inhibition of nitric oxide were investigated.Method. Measurement of free Ca^2 ([Ca^2 ]i) of cultured rat tail arterial smooth muscle cells using Fura-2/AM dual excitation wavelength spectrofluorometer.Results. There are two components of [Ca^2 ]i can be evoked by ATP. One part is Ca^2 entry fixxn Ca^2 channel and formed a plateau. The another is a peak that rdeased from Ca^2 store. Both of them can be inhibited by NO.Conclusion. The ATP induced [ Ca^2 ]i rise that release Ca^2 from both Insp3 and ryanochine receptors and Ca^2 entry through calcium channels. The inhibition of NO on ATP induced [ Ca^2 ]i rise that was mediated by cGMP.     

老龄小鼠心肌细胞膜的钙激活钾通道

21～24月龄的C57BL/6J小鼠左心室乳头肌的单个细胞用酶法分离。用膜片钳(patchclamp)技术的细胞封接(cellattached)方式,步阶式钳制膜电位,在±60mV范围内,记录钙激活钾通道活动。细胞池液(mmol/L)为:KCl 6;NaCl 123;MgCl_2 1.2;NaH_2Po_4 1.2;CaCl_2 2.5,Hepes 1.2;Glueose 5。电极液(mmol/L)除KCl 126外其余同细胞池液,pH值均为7.4。在上述条件下记录到117.5±9.0pS(n=5),182.9±17.0(n=6)和285.1±12.0pS(n=6)三种电导的通道活动。通道活动表现出爆发式开放和长时间开放两种方式。爆发式