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探讨八肽胆囊收缩素(CCK-8)对豚鼠单个心肌细胞内游离钙浓度([Ca2+]i)的影响及其信号转导机制。Fluo 3-AM标记酶消化法分离的单个心室肌细胞,用激光共聚焦显微镜测定细胞内[Ca2+]i的浓度。[Ca2+]i的变化用荧光强度(Fi)和相对荧光强度(Fi/F0％)表示。实验结果如下:(1)在含Ca2+1.0 mmol/L的Tyrode’s液中,CCK-8(1-104pmol/L)均可引起[Ca2+]i快速显著上升(P<0.01)。(2)用钙离子鳌合剂EGTA(3 mmol/L)和钙离子通道阻断剂nisoldipine(0.5μmol/L)预孵育心肌细胞5 min,CCK-8(102pmol/L)仅可引起[Ca2+]i缓慢轻度上升(P<0.01)。(3)用非选择性CCK受体拮抗剂丙谷胺(proglumide 6μmol/L)或酪氨酸激酶抑制剂genistein(1μmol/L)预孵育心肌细胞5 min,则完全抑制CCK-8诱导的[Ca2+]i升高(P<0.01)。 CCK-8可通过激活其受体控制的Ca2+通道,引起Ca2+内流,诱导细胞内Ca2+释放,引起豚鼠单个心肌细胞内[Ca2+]i上升,此作用可能由酪氨酸激酶介导。
To investigate the effects of cholecystokinin octapeptide (CCK-8) on intracellular free calcium concentration ([Ca2 +] i) in guinea pig single myocytes and its signal transduction mechanism. Single ventricular myocytes were isolated by Fluo 3-AM labeled enzyme digestion and the [Ca2 +] i concentration in the cells was measured by laser confocal microscopy. Changes in [Ca2 +] i are expressed as fluorescence intensity (Fi) and relative fluorescence intensity (Fi / F0%). The results are as follows: (1) CCK-8 (1-104pmol / L) induced a rapid and significant increase of [Ca2 +] i in Tyrode’s solution containing 1.0 mmol / L of Ca2 + (P <0.01). (2) CCK-8 (102 pmol / L) preincubated cardiomyocytes for 5 min with calcium chelator EGTA (3 mmol / L) and calcium channel blocker nisoldipine i slowly and mildly increased (P <0.01). (3) Preincubation of cardiomyocytes with proglumide 6 μmol / L or genistein (1 μmol / L), a nonselective CCK receptor antagonist for 5 min, completely inhibited CCK-8-induced [ Ca2 +] i increased (P <0.01). CCK-8 can induce Ca2 + influx via Ca2 + channel of its receptor and induce intracellular Ca2 + release, leading to the increase of [Ca2 +] i in single cardiomyocytes in guinea pigs, which may be mediated by tyrosine kinase.