Kim Aeran, Bae Young Min, Kim Junghwan, Kim Bokyung, Ho Won Kyung, Earm Yung E, Cho Sung Il
Department of Physiology, College of Medicine, Konkuk University, 322 Danwol-dong, Choongju 380-701, South Korea.
Eur J Pharmacol. 2004 Jan 12;483(2-3):117-26. doi: 10.1016/j.ejphar.2003.10.028.
We investigated the effect of bisindolylmaleimide (I), a widely used protein kinase C (PKC) inhibitor, on the voltage-dependent K(+) (Kv) currents of rat mesenteric arterial smooth muscle cells using the whole-cell patch-clamp technique. Bisindolylmaleimide (I) reversibly and dose-dependently inhibited the Kv currents with an apparent K(d) value of 0.23+/-0.001 microM. The blockade was apparently through the acceleration of the decay rate of the Kv currents. The apparent rate constants of association and dissociation for bisindolylmaleimide (I) were 17.9+/-1.6 microM(-1) s(-1) and 4.1+/-1.5 s(-1), respectively. The inhibition of Kv current by bisindolylmaleimide (I) was steeply voltage-dependent between -30 and 0 mV (voltage range of channel activation). Bisindolylmaleimide (I) had no effect on the steady-state activation and inactivation of the Kv currents. Applications of trains of pulses at 1 or 2 Hz lead to a progressive increase in the bisindolylmaleimide (I)-blockade, and the recovery from bisindolylmaleimide (I)-block at -80 mV exhibited a time constant of 577.2+/-52.7 ms. Bisindolylmaleimide (V), an inactive analogue of bisindolylmaleimide (I), similarly inhibited the Kv currents with an apparent K(d) value of 1.48+/-0.004 microM, but other PKC inhibitor chelerythrine little affected the Kv currents. These results suggest that bisindolylmaleimide (I) directly inhibits the Kv currents of rat mesenteric arterial smooth muscle cells independently of PKC inhibition, in a state-, voltage-, time- and use-dependent manner.
我们使用全细胞膜片钳技术，研究了广泛应用的蛋白激酶C（PKC）抑制剂双吲哚马来酰亚胺（I）对大鼠肠系膜动脉平滑肌细胞电压依赖性钾离子（Kv）电流的影响。双吲哚马来酰亚胺（I）可逆且剂量依赖性地抑制Kv电流，其表观解离常数（Kd）值为0.23±0.001微摩尔。这种阻断显然是通过加速Kv电流的衰减速率实现的。双吲哚马来酰亚胺（I）的表观结合和解离速率常数分别为17.9±1.6微摩尔⁻¹秒⁻¹和4.1±1.5秒⁻¹。在-30至0毫伏（通道激活的电压范围）之间，双吲哚马来酰亚胺（I）对Kv电流的抑制作用强烈依赖于电压。双吲哚马来酰亚胺（I）对Kv电流的稳态激活和失活没有影响。以1或2赫兹的频率施加脉冲串会导致双吲哚马来酰亚胺（I）阻断作用逐渐增强，在-80毫伏时从双吲哚马来酰亚胺（I）阻断状态恢复的时间常数为577.2±52.7毫秒。双吲哚马来酰亚胺（V）是双吲哚马来酰亚胺（I）的无活性类似物，同样抑制Kv电流，其表观Kd值为1.48±0.004微摩尔，但其他PKC抑制剂白屈菜红碱对Kv电流影响很小。这些结果表明，双吲哚马来酰亚胺（I）以一种状态、电压、时间和使用依赖性的方式，独立于PKC抑制作用直接抑制大鼠肠系膜动脉平滑肌细胞的Kv电流。
