Received 2002-03-29 Accepted 2002-09-09

This project was supported by the National Natural Science Foundation of China (No. 30070279).

*Corresponding author. Tel: +86-27-83692622; Fax: +86-27-83692608; E-mial: Yimeidu@hotmail.com

Inhibitory effect of adrenomedullin on L-type calcium currents in guinea-pig ventricular myocytes

DU Yi-Mei*, TANG Ming, LIU Chang-Jin, LUO Hong-Yan, HU Xin-Wu

Department of Physiology, Tongji Medical College of Huazhong University of Science and Technology,

Wuhan 430030

Abstract: The effects of adrenomedullin (ADM) on the L-type calcium currents (I_{Ca, L}) and the mechanism of the signal transduction process were studied. Enzymatically isolated guinea-pig ventricular myocytes were used to measure I_{Ca, L} with whole-cell patch-clamp techniques. ADM at concentration 1~100 nmol/L decreased ICa, L in a dose-dependent manner (P<0.05). ADM22-52 (100 nmol/L), a specific ADM-receptor antagonist, completely abolished the ADM-induced inhibition of I_{Ca, L}. Pretreatment of the cells with H-89 (10 μmol/L) , a specific PKA inhibitor, did not attenuate the effects of ADM. Intracellular application of 10 μmol/L PKC19-36 , a specific PKC inhibitor, prevented the ADM-induced inhibition of the I_{Ca, L}, while the specific PKC activator PMA could mimic the effects of ADM on the I_{Ca, L}. 1 μmol/L PMA decreased the I_{Ca, L} by 32.26±4.20% (P<0.05). These findings indicate that ADM can inhibit the I_{Ca, L} in guinea-pig ventricular myocytes, the inhibition is mediated by the specific ADM-receptor and an activation of protein kinase C.

Key words: adrenomedullin; ventricular myocyte; receptor; protein kinase C; L-type calcium channel; patch clamp technique

肾上腺髓质素对豚鼠心室肌细胞L-型钙通道的调制

杜以梅, 唐明, 刘长金, 骆红艳, 胡新武

华中科技大学同济医学院生理系, 武汉 430030

摘要: 应用全细胞膜片钳技术研究了肾上腺髓质素(ADM)对豚鼠心室肌细胞L-型钙电流(I_{Ca, L})的影响及其信号传导机制。结果发现: ADM (1～100 nmol/L)浓度依赖性抑制I_{Ca, L} (P<0.05), 并可被ADM特异受体阻断剂ADM22-52 (100 nmol/L)完全阻断。用蛋白激酶A特异拮抗剂H-89 (10 μmol/L) 预处理, 对ADM抑制I_{Ca, L}的作用无影响。但用蛋白激酶C (PKC)特异性拮抗剂PKC19-36预处理, 可完全阻断ADM的抑制效应; 而PKC特异性激动剂PMA则可以模仿ADM的抑制效应(P<0.05)。上述结果提示: ADM作用于特异性ADM受体可浓度依赖性地抑制豚鼠心室肌细胞I_{Ca, L}, 而此作用可能是PKC介导的。

关键词: 肾上腺髓质素; 心室肌细胞; 受体; 蛋白激酶C; L-型钙通道; 膜片钳技术

中图分类号: Q463; R 331.3