Effect of calcitonin gene-related peptide on action potential duration in rat cardiomyocytes and role of K ATP channels / 中华麻醉学杂志

ABSTRACT

Objective:To evaluate the effect of calcitonin gene-related peptide (CGRP) on action potential duration (APD) in rat ventricular myocytes and the role of ATP-sensitive potassium (K ATP) channels. Methods:Ventricular myocytes ( n=6)acutely isolated from clean-grade Sprague-Dawley rats by enzymatic hydrolysis were obtained.Using the method of self-control before and after administration, the cells were first perfused with Tyrode′s solution alone for 2 min, and then with Tyrode′s solution containing CGRP 10 -10 mol/L, CGRP8-37 10 -9 mol/L and glibenclamide 10 -5 mol/L sequentially for 2 min.The APD was recorded, and K ATP channel current density was determined by whole-cell patch-clamp technique, and APD at 90% of repolarization(APD 90) was calculated. Results:Compared with the results after giving Tyrode′s solution alone, APD 90 of ventricular myocytes was significantly shortened, and the K ATP channel current density of ventricular myocytes was increased after giving CGRP ( P<0.01). The APD 90 of ventricular myocytes was significantly prolonged, and K ATP channel current density of ventricular myocytes was decreased after giving CGRP 8-37 or glibenclamide as compared with that after giving CGRP ( P<0.05). Conclusion:CGRP can shorten APD of rat ventricular myocytes through its specific receptor, and activation of K ATP channels is involved in this process.