9-蒽羧酸对豚鼠心室肌动作电位和L型Ca电流的影响

EFFECTS OF ANTHRACENE-9-CARBOXYLIC ACID ON CARDIAC VENTRICULAR ACTION POTENTIAL DURATION AND L-TYPE Ca^(2+) CHANNEL IN GUINEA PIG

目的 :研究 9 蒽羧酸 (9 AC)对豚鼠心室肌动作电位 (AP)和L型Ca电流 (ICa)的影响。方法 :电流钳配合制霉菌素膜穿孔方法记录心室肌动作电位 ,用全细胞式膜片钳 (Whole cellrecording)技术记录ICa。结果 :在低Cl-状态下 ,β肾上腺素能受体激动剂异丙肾上腺素 (ISO)可使动作电位时程 (APD)明显延长。 9 AC单独使用时对AP无作用 ,但在ISO的作用下 ,蛋白磷酸酶抑制剂 9 AC可使APD进一步延长 ,ISO和 9 AC的作用可被Ca2 + 通道阻断剂硝苯地平 (3μmol/L)所反转。电压箝实验发现 ,在 β 肾上腺素能受体激动剂ISO激发下 ,9 AC使ICa的幅度进一步增加。结论 :9 AC与ISO有协同作用。本文结果提示 9 AC敏感性蛋白磷酸酶参与Ca2 + 通道的调控过程。

Aim and methods: The effects of anthracene 9 carboxylic acid (9 AC) on guinea pig cardiac ventricular action potential (AP) and L type Ca 2+ current (I Ca ) were investigated using the perforated patch recordings and the whole cell patch clamp technique, respectively. Results: Under low Cl - condition (1.8 mmol/L [Cl -] 0/2.5 mmol/L [Cl -] i), isoproterenol (ISO), a B adrenoceptor agonist, induced a significant increase in the action potential duration (APD), especialty in APD 50 . 9 AC alone did not show any influence on AP, however, in the presence of ISO, extracellular application of 9 AC made the APD further prolonged. The effects of both ISO and 9 AC were reversed completely by a Ca 2+ channel blocker, nifedipine (3 μmol/L). 9 AC was found to increase cardiac L type Ca 2+ current (I Ca ) after the channels were first activated by ISO. Conclusion: The present results indicated that there is a synergistic effect of 9 AC and ISO on I Ca , suggesting that 9 AC sensitive phosphatase is responsible not only for the dephosphorylation of CFTR Cl - channels, but also for that of L type Ca 2+ channels.