Inhibition of L-type calcium current in rat ventricular cells by the tyrosine kinase inhibitor, genistein and its inactive analog, daidzein.
Inhibition of L-type calcium current in rat ventricular cells by the tyrosine kinase inhibitor, genistein and its inactive analog, daidzein.
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DOI：
10.1006/jmcc.1996.0075
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发表时间：
1996-04
影响因子：
5
通讯作者：
Hisashi Yokoshiki;Kotaro Sumii;Nicholas Sperelakis
中科院分区：
文献类型：
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作者：
Hisashi Yokoshiki;Kotaro Sumii;Nicholas Sperelakis
使用全细胞膜片钳技术，在新鲜分离的年轻（第 10-18 天）大鼠心室细胞中检查金雀异黄酮（酪氨酸激酶的特异性抑制剂）对 L 型 Ca2+ 通道的影响。金雀异黄素浴的应用以浓度依赖性方式降低了 L 型 Ca2+ 电流 [I(Ca(L))]。 I(Ca(L)) 的最大抑制约为 40%（浓度高于 100 µM 时达到）；半抑制浓度 (IC50) 为 11 microM。金雀异黄素（施加约 5 分钟）的效果在冲洗长达 5 分钟后很难逆转。金雀异黄素使稳态失活曲线的半抑制电位 (Vh) 向负方向移动 7 mV（100 microM 时），斜率因子也略有变化；激活曲线不受影响。大豆黄酮在结构上与染料木黄酮相关，但对（EGF受体的）酪氨酸激酶活性几乎没有抑制作用，出乎意料地对I(Ca(L))具有几乎相同的抑制作用。这些观察表明金雀异黄素调节大鼠心室细胞中 I(Ca(L)) 的两种可能性：(a) 酪氨酸激酶磷酸化慢 Ca2+ 通道； (b) 直接抑制慢 Ca2+ 通道（即独立于酪氨酸激酶活性的抑制）。
Effects of genistein, a specific inhibitor of tyrosine kinase, on the L-type Ca2+ channels were examined in freshly isolated young (days 10-18) rat ventricular cells using the whole-cell patch-clamp technique. Bath application of genistein decreased the L-type Ca2+ current [I(Ca(L))] in a concentration-dependent manner. The maximal inhibition of I(Ca(L)) was about 40% (attained at concentrations above 100 microM); the concentration for half-inhibition (IC50) was 11 microM. The effect of genistein (applied for about 5 min) was poorly reversible after washout for up to 5 min. The potential for half-inhibition (Vh) of the steady-state inactivation curve was shifted in the negative direction by 7 mV (at 100 microM) by genistein, and the slope factor was also slightly changed; the activation curve was not affected. Daidzein, which is structurally related to genistein, but has little inhibitory effect on tyrosine kinase activity (of the EGF receptor), unexpectedly had almost the same inhibitory effect on I(Ca(L)). These observations suggest two possibilities for modulation of I(Ca(L)) in rat ventricular cells by genistein: (a) phosphorylation of the slow Ca2+ channels by tyrosine kinase; and (b) direct inhibition of the slow Ca2+ channels (i.e. independent of inhibition of tyrosine kinase activity).