腺苷对心肌细胞的电生理作用及机制探讨

Study of electrophysiologic effects and mechanism of adenosine on myocardium from guinea pig heart

采用微电极技术及膜片钳全细胞记录方式，研究腺苷对豚鼠心肌细胞的电生理作用及其机制。结果表明：腺苷可明显缩短心房肌及房室结区细胞动作电位时程，降低房室结区细胞动作电位振幅、零相最大去极化速率，膜片钳上证明此为腺苷加强延迟整流性钾通道电流和抑制Ｌ型钙通道电流所致。对心室肌细胞无此明显的作用，但应用异丙肾上腺素后证明腺苷能拮抗β１受体的作用。腺苷的作用能被选择性腺苷Ａ１受体阻断剂８－环戊基－１，３－二丙基黄嘌呤消除，提示腺苷对心肌细胞的作用由Ａ１受体介导。本研究也探讨了腺苷对心房肌和心室肌作用区别的可能原因，以及心房肌和心室肌对异丙肾上腺素合用腺苷时反应不同的可能机制。

Using microelectrode and patch clamp technique, the electrophysiologic effects and the mechanism of adenosine were studied on cardiomyocytes from guinea pig. The results indicated that adenosine shortened action potential durations of atrial and atrioventricular junctional myocytes, and reduced action potential amplitude and Vmax of atrioventricular junctional cells. These effects were explained by patch clamp studies demonstrated that adenosine increased I K and inhibited I Ca L . Adenosine had no obvious direct effects on ventricular myocytes, but after using isoproterenol, adenosine antagonized the effects of β 1 receptor. These effects of adenosine were prevented by 8 cyclopentyl 1, 3 dipropylxathine (DPCPX) which suggested that the effects of adenosine were mediated by A 1 receptor. The possible mechanisms by which adenosine had different effects on atrial and ventricular myocytes and the possible mechanisms of different reactions of atrium and ventricle to isoproterenol and adenosine were also investigated in the study.