茶黄素对大鼠心室肌细胞内游离钙浓度的影响

目的研究茶黄素对大鼠心室肌细胞内游离钙浓度(Ca2+]i)的影响并探讨其可能机制。方法用激光共聚焦显微镜探测细胞内游离钙浓度,结果用相对荧光强度((FI-FI0)/FI0,%;FI0:对照;FI:给药)表示。结果①茶黄素(10,20,40μmol.L-1)对正常台氏液中心肌细胞内游离钙浓度没有影响,却可浓度依赖性地降低模拟缺血液中心室肌细胞Ca2+]i的增加。②预先应用L型钙通道开放剂Bay k8644,可大部分取消茶黄素(20μmol.L-1)在模拟缺血液中的作用。③茶黄素(20μmol.L-1)能明显抑制无钙台氏液中由低浓度ryanodine引起的Ca2+]i增加。④当细胞外液钙浓度由1 mmol.L-1增加到10 mmol.L-1而诱发心室肌细胞钙超载时,部分心室肌细胞产生可传播的钙波,茶黄素(20μmol.L-1)可降低钙波发生的频率和持续时间,最终阻断钙波并降低Ca2+]i。结论茶黄素可抑制电压门控性钙通道的外钙内流和减少肌浆网的内钙释放从而降低Ca2+]i。

Effect of theaflavin on intracellular free calcium concentration in rat ventricular myocytes

Aim To observe the effects of theaflavin on intracellular calcium concentration(i) level in rat ventricular myocytes and discuss the possible mechanisms.Methods The effects of theaflavin oni were investigated in rat ventricular myocytes.i was detected by laser confocal microscopy and represented by relative fluorescent intensity(FI-FI0)/FI0,%;FI0:control;FI:administration of drugs).Results ① Theaflavin(10,20,40 μmol·L-1) had no effect on the i of ventricular myocytes in normal Tyrode′s solution.However,it reduced the i of ventricular myocytes in simulated ischemia solution in a concentration-dependent manner.② Pretreatment with Bay k8644(0.5 μmol·L-1) mostly abolished the effects of theaflavin(20 μmol·L-1) in simulated ischemia solution.③ Theaflavin(20 μmol·L-1) markedly inhibited the low concentration of ryanodine-induced i increase in Ca2+-free Tyrode′s solution.④ When the propagating waves of elevated i(Ca2+ waves) were produced by increasing extracellular Ca2+ concentration from 1 mmol·L-1to 10 mmol·L-1,theaflavin(20 μmol·L-1) could block the propagating waves of elevated i(Ca2+ waves),reduce the frequency and duration of propagating waves,and reduce i as well.Conclusion Theaflavin may reduce the i in isolated rat ventricular myocytes via inhibiting Ca2+ influx by voltage-dependent Ca2+ channel and alleviating Ca2+ release from sarcoplasmic reticulum(SR).