Ji En-Sheng, Yin Jing-Xiang, Ma Hui-Jie, He Rui-Rong
Department of Physiology, Institute of Basic Medicine, Hebei Medical University, Shijiazhuang, Hebei 050017, China.
Sheng Li Xue Bao. 2004 Aug 25;56(4):466-70.
This paper was aimed to study the effect of genistein (GST) on L-type calcium current (I(Ca,L)) in isolated guinea pig ventricular myocytes using whole cell patch-clamp recording technique. The results are as follows. (1) GST (10, 50, 100 micromol/L) reduced the voltage-activated peak amplitude of I(Ca,L) in a concentration-dependent manner. Daidzein (100 micromol/L), a structural analogue of GST which has little or no inhibitory effect on tyrosine kinase, produced no effect over the same concentration range on I(Ca,L) (n=5, P>0.05). (2) GST up- shifted the current-voltage (I-V) curve, but the characteristics of I-V relationship were not significantly altered, and the maximal activation voltage of I(Ca,L) was not different from that of control. GST did not affect the activation kinetics of I(Ca,L). (3) GST markedly shifted the steady-state inactivation curve of I(Ca,L) to the left, and accelerated the voltage-dependent steady-state inactivation of I(Ca,L). V(0.5) value was -28.6 +/-0.6 mV in the control and -32.8 +/-1.1 mV in the presence of GST. The kappa values were 5.8 +/-0.5 mV and 6.5 +/-0.9 mV, respectively (n=6, P<0.05). (4) GST markedly shifted the curve of time-dependent recovery of I(Ca,L) from the steady-state inactivation to the right, and slowed down the recovery of I(Ca,L) from inactivation (n=7, P<0.01). (5) Sodium orthovanadate (1 mmol/L), a potent inhibitor of tyrosine phosphatase, significantly inhibited GST-induced inhibition (n=6, P<0.01). From the results obtained it is concluded that genistein inhibits I(Ca,L) and acts on the inactivated state of L-type calcium channel. This inhibitory effect of GST involves protein tyrosine kinase inhibition in guinea pig ventricular myocytes.
本研究旨在采用全细胞膜片钳记录技术，研究染料木黄酮（GST）对豚鼠离体心室肌细胞L型钙电流（I(Ca,L)）的影响。结果如下：（1）GST（10、50、100 μmol/L）以浓度依赖性方式降低I(Ca,L)的电压激活峰值幅度。大豆苷元（100 μmol/L）是GST的结构类似物，对酪氨酸激酶几乎没有抑制作用，在相同浓度范围内对I(Ca,L)无影响（n = 5，P>0.05）。（2）GST使电流-电压（I-V）曲线向上移位，但I-V关系特性未显著改变，I(Ca,L)的最大激活电压与对照组无差异。GST不影响I(Ca,L)的激活动力学。（3）GST使I(Ca,L)的稳态失活曲线明显向左移位，并加速I(Ca,L)的电压依赖性稳态失活。对照组的V(0.5)值为-28.6±0.6 mV，GST存在时为-32.8±1.1 mV。κ值分别为5.8±0.5 mV和6.5±0.9 mV（n = 6，P<0.05）。（4）GST使I(Ca,L)从稳态失活的时间依赖性恢复曲线明显向右移位，并减慢I(Ca,L)从失活状态的恢复（n = 7，P<0.01）。（5）酪氨酸磷酸酶的强效抑制剂原钒酸钠（1 mmol/L）显著抑制GST诱导的抑制作用（n = 6，P<0.01）。从所得结果得出结论，染料木黄酮抑制I(Ca,L)并作用于L型钙通道的失活状态。GST的这种抑制作用涉及豚鼠心室肌细胞中蛋白酪氨酸激酶的抑制。
