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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。
Objective To study the effect of BTHP on the action potential of guinea pig papillary muscles and the delayed rectifier potassium current of single ventricular myocytes. Methods The drugs were introduced into papillary muscle cells by using voltage pulse and the action potentials were measured by standard microelectrode method. Drugs were introduced into single ventricular myocytes by diffusion of concentration difference. Whole-cell patch clamp technique was used to record the delayed rectifier potassium current (IK ). Results 100 μmol·L-1BTHP prolonged APD20 and APD90 by 135% and 205% respectively. 30 μmol·L-1BTHP decreased IK and IK, tail from (14 1 ± 2 2) pA · pF-1 and (40 ± 0 6) pA · pF-1 to (9 4 ± 1 3) pA · pF-1 and (2 1 ± 1 0) pA · pF-1, the decreasing rates were 33 2% and 35 3% respectively. The drug to IK and IK, tail I V curve amplitude decreases, the shape of the curve has no obvious effect. Conclusion Intracellular BTHP can block the delayed rectifier potassium current and prolong the action potential duration.