The Regulation Effects of β2-AR on INCX in Myocytes from Infarcted Rat Heart

Hui YANG; Wei WU; Chun-yu DENG

摘要：Objectives This study is designed to investigate the regulation effects of β2-adrenergic receptors (AR) on expression of the Na+-Ca2+ exchanger (INCX) in myocytes from the infarcted rat heart. Methods Twenty-eight adult Wistar rats were randomly divided into four groups : the control group, the two weeks, four weeks and eight weeks post-myocardial infarction (post-MI) groups, respectively. The chest of rat was opened and a ligature was placed around the left anterior descending coronary artery. Rats in control group were sham-operated without the coronary artery ligation.After the operation, rats were fed for two, four or eight weeks respectively. Myocytes were enzymatically disassociated by Langendorff perfusion. The whole cell-patch clamp recording technique was used to record INCX in specific pipette solution and superfusion according to the specific holding potential and command potential program. Results The INCX in ventricular myocytes from the border zone of infarcted myocardium increased significantly at eight weeks after MI(0.51±0.12 pA/pF vs 1.07±0.21 pA/pF, P＜0.05). β2-AR agonist increased INCX more strongly in myocytes from post-MI heart than in controls. β2-AR antagonist attenuated the rise of INCX. which was induced by β-AR agonist, more strongly in myocytes from post-MI heart than in controls, whereas β1-AR antagonist reversed the effect of β2-AR antagonist. Conclusion The regulation effects of β2-AR on INCX in myocytes were stronger after MI. It suggested that β2-AR had closer relationship with the genesis of malignant arrhythmia after MI in adult Wistar rats.