Search for a cardiac Cl^- channel blocker : Development of a novel type of antiarrhythmic drug

肿胀诱导的Cl^-通道的激活可能参与心肌缺血和再灌注期间心律失常的发生。为了评估Cl^-通道的病理生理作用，找到Cl^-通道的特异性阻断剂是很重要的，因为已知包括芪类衍生物在内的其他Cl^-通道阻断剂会影响其他离子通道。我们使用膜片钳技术检测了许多具有喹啉酮结构的化合物对暴露于低渗溶液（54- 63%渗透压）的离体豚鼠心房细胞诱导的Cl^-电流的影响。在所检测的许多化合物中，OPC 18360（1-甲基-4-（1-哌嗪基）-2（1H）喹啉酮盐酸盐）在100 μ M浓度下显著抑制肿胀诱导的Cl^-电流，而它轻微增强1 μ M异丙肾上腺素激活的cAMP依赖性Cl^-电流。相同浓度的化合物不能影响L型Ca^++电流， ...更多信息 延迟整流钾电流（<K1>I_K）和钠离子电流（I_K）也略有降低<Na>。在电流钳模式下，药物略微延长心房细胞记录的动作电位。在豚鼠离体乳头肌中，OPC 18360略微增加了发达的张力。还在麻醉开胸犬中评价了OPC 18360对缺血和再灌注诱导的心律失常的影响。1 mg/kg OPC 18360静脉给药对平均血压、心率和ECG参数无显著影响。OPC 18360减少了冠状动脉闭塞30分钟的总室性早搏的数量。然而，该药物未能防止冠状动脉闭塞和再灌注期间的心室颤动。因此，可以得出结论，OPC 18360是肿胀诱导的Cl^-通道的特异性阻断剂。然而，可能需要进一步寻找更有效的Cl^-通道阻滞剂，以开发临床适用的抗肿瘤药物。少

Activation of swelling-induced Cl^- channels may be involved in the genesis of cardiac arrhythmias during myocardial ischemia and reperfusion. In order to evaluate the pathophysiological role of the Cl^- channel, it would be important to find a specific blocker of the Cl^- channels, because other Cl^- channel blockers including stilben derivatives are known to affect other ion channels. We examined effects of many chemical compounds having quinolinone structures on the Cl^- current induced by exposure to a hypotonic solution (54-63 % osmolarity) in isolated guinea pig atrial cells using patch clamp techniques. Among many chemical compounds examined, OPC 18360 (1-methyl-4- (1-piperazinyl) -2 (1H) quinolinone hydrochloride) at a concentration of 100 muM significantly inhibited the swelling-induced Cl^- current whereas it slightly enhanced the cAMP-dependent Cl^- current activated by 1 muM isoproterenol. The compound at the same concentration failed to affect the L-type Ca^<++> current an … More d the inward rectifier K^+ current (I_<K1>) although it slightly decreased the delayd rectifier K^+ current (I_K) and the Na^+ current (I_<Na>). The drug slightly prolonged the action potential recorded from atrial cells in the current clamp mode. In isolated papillary muscles of guinea pigs OPC 18360 slightly increased the developed tension. Effects of OPC 18360 on the ischemia-and reperfusion-induced arrhythmias were also evaluated in anesthetized open chest dogs. Intravenous administration of 1 mg/kg OPC 18360 did not significantly affect the mean blood pressure, heart rate and ECG parameters. OPC 18360 decreased the number of total ventricular premature contractions during coronary occlusion of 30 min. However, the drug failed to prevent ventricular fibrillation during coronary occlusion and reperfusion. Thus, it can be concluded that OPC 18360 is a specific blocker of the swelling-induced Cl^- channel. However, further search for more potent Cl^- channel blocker may be needed for the development of a clinically applicable antiarrhythmic drug. Less