苄基四氢巴马汀细胞内用药对豚鼠乳头状肌动作电位和心室肌细胞延迟整流钾电流的作用

INTRACELLULAR EFFECTS OF BENZYLTETRAHYDROPALMATINE ON THE ACTION POTENTIAL AND DELAYED RECTIFIER POTASSIUM CURRENTS IN GUINEA PIG PAPILLARY MUSCLE AND VENTRICULAR MYOCYTES

目的 研究将苄基四氢巴马汀 (BTHP)导入细胞内对豚鼠乳头状肌动作电位及单个心室肌细胞延迟整流钾电流的影响。方法 利用外加电压脉冲将药物导入乳头状肌细胞内 ,并用标准微电极方法测定动作电位 ;利用浓度差扩散方式使药物进入单个心室肌细胞内 ,采用全细胞膜片钳技术记录延迟整流钾电流 (IK)。结果 10 0 μmol·L-1BTHP使APD2 0 和APD90 分别延长 13 5 %和 2 0 5 %。 30 μmol·L-1BTHP使IK 和IK ,tail分别从 (14 1± 2 2 )pA·pF-1和 (4 0± 0 6 ) pA·pF-1降至 (9 4± 1 3) pA·pF-1和 (2 1± 1 0 ) pA·pF-1,下降率分别为 33 2 %和 35 3%。该药使IK 和IK ,tail的I V曲线幅度降低 ,对曲线形状影响不明显。结论 BTHP入细胞内后可阻滞延迟整流钾电流和延长动作电位时程。

AIM To investigate the effects of benzyltetrahydropalmatine (BTHP) on the action potential (AP) of guinea pig papillary muscle and delayed rectifier potassium currents ( I _K )of single ventricular myocyte when administered intracellularly. METHODS Standard microelectrode was applied to examine the characteristics of the AP. BTHP included in the pipette internal solution was dialyzed into papillary muscle cell by using a pulse with duration of 50 ms, voltage of +40 V. The parameters of AP were recorded after 20 min of intracellular dialysis. Whole cell patch clamp technique was used to measure the I _K and BTHP was applied intracellularly in single ventricular myocyte by cell dialysis method. RESULTS 100 μmol·L -1 BTHP prolonged APD_ 20 and APD_ 90 by 13 5% and 20 5%, respectively. Furthermore, 30 μmol·L -1 BTHP was demonstrated to decline I _K and I _ K,tail from (14 1±2 2) pA·pF -1 and (4 0±0 6) pA·pF -1 to (9 4±1 3) pA·pF -1 and (2 6±1 0) pA·pF -1 with inhibition rates of 33 2% and 35 3%, respectively. BTHP reduced the amplitude of I - V curves of I _K and I _ K,tail , but did not affect the shape of them significantly. CONCLUSION The results showed that BTHP used intracellularly can block I _K and prolong the duration of action potential(APD).