Genistein inhibits cardiac L-type Ca2+ channel activity by a tyrosine kinase-independent mechanism
Genistein inhibits cardiac L-type Ca2+ channel activity by a tyrosine kinase-independent mechanism
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DOI：
10.1124/mol.62.3.554
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发表时间：
2002-09-01
影响因子：
3.6
通讯作者：
Harvey, RD
中科院分区：
文献类型：
--
作者：
Belevych, AE;Warrier, S;Harvey, RD
有研究表明，蛋白酪氨酸激酶(PTK)活性可直接调节心肌L型钙通道。这一结论在很大程度上是基于观察到PTK抑制剂金雀异黄素能抑制心脏L型钙电流。本研究的目的是确定染料木素抑制心肌L型钙通道活性的作用是否与抑制PTK活性有关。金雀异黄素显著降低用全细胞膜片钳技术记录的豚鼠心肌细胞L钙电流的幅度。然而，这种效应与药物的细胞外应用有关，而不是与细胞内应用相关。蛋白酪氨酸磷酸酶抑制剂过氧钒(PVN)对基础钙电流无影响。PVN对金雀异黄素的抑制作用也无明显作用。用含有ATPGammaS的吸管溶液对细胞进行内部灌流，以防止磷酸化依赖过程的可逆性。这种治疗并没有改变染料木素的抑制作用，尽管它确实导致了不可逆的蛋白激酶A依赖的钙电流调节。应用结构上与金雀异黄素无关的PTK抑制剂Lavenustin A并不影响钙电流幅度。金雀异黄素的抑制作用还与钙通道失活电压依赖性的超极化转变有关。这些结果与以下结论一致，即心肌L型钙电流不受PTK活性的直接调节，金雀异黄素的抑制作用是由于对通道的直接非催化阻断。
It has been suggested that protein tyrosine kinase (PTK) activity can directly regulate cardiac L-type Ca2+ channels. This conclusion is based to a large extent on the observation that the PTK inhibitor genistein can inhibit the cardiac L-type Ca2+ current. The purpose of the present study was to determine whether the ability of genistein to inhibit cardiac L-type Ca2+ channel activity is due to inhibition of PTK activity. Genistein significantly reduced the magnitude of the L-type Ca2+ current in guinea pig ventricular myocytes recorded using the whole-cell patch-clamp technique. However, this effect was associated with extracellular, not intracellular, application of the drug. Peroxovanadate (PVN), a potent protein tyrosine phosphatase inhibitor, had no effect on the basal Ca2+ current. PVN was also ineffective in preventing the inhibitory effect of genistein. Internal perfusion of cells with a pipette solution containing ATPgammaS was used to prevent reversibility of phosphorylation-dependent processes. This treatment did not alter the inhibitory effect of genistein, although it did result in irreversible protein kinase A-dependent regulation of the Ca2+ current. Bath application of lavendustin A, a PTK inhibitor that is structurally unrelated to genistein, did not affect the Ca2+ current amplitude. The inhibitory effect of genistein was also associated with a hyperpolarizing shift in the voltage dependence of Ca2+ channel inactivation. These results are consistent with the conclusion that the cardiac L-type Ca2+ current is not directly regulated by PTK activity and that the inhibitory effect of genistein is due to direct non-catalytic blockade of the channels.