机械牵张对大鼠心室肌蛋白激酶B磷酸化及心钠素分泌的影响

目的:研究机械牵张对大鼠心肌蛋白激酶B(Akt)活化和心钠素(ANF)分泌的影响。方法:采用Langendorff方法灌流大鼠心脏,膨胀球囊持续牵张左心室,从左心室游离心肌,提取胞浆蛋白,用Western blot检测磷酸化Akt、总Akt水平;收集冠脉流出液,用放射免疫分析法检测冠脉流出液中ANF含量。结果:持续牵张不影响灌流心脏的心率和冠脉流出量。但经过20min持续牵张,牵张组心脏灌流液中ANF含量(209.89±65.45pg/ml)较对照组(108.84±25.18pg/ml)明显增高(P<0.01);牵张组大鼠左心室心肌组织磷酸化Akt水平(0.76±0.03)明显高于对照组(0.32±0.02),而总Akt水平与对照组相比无显著性差异。结论:机械牵张可引起心脏心钠素的分泌增加,其机制可能与胞内Akt信号通路的激活有关。

Effect of Mechanical Stretch on Phosphorylation of Protein Kinase B and Secretion of Atrial Natriuretic Factor in Rat Ventricular Myocardium

Objective: To investigate the effect of mechanical stretch on the activation of protein kinase B (PKB/Akt) in rat ventricular myocardium and secretion of atrial natriuretic factor (ANF). Method: In a Langendorff perfusion preparation, the rat hearts were continuously inflated by an intraventricular balloon, then cytoplasmic proteins were isolated from free ventricular wall and the levels of phospho-Akt, total Akt were detected by Western blot, coronary effluents were collected and the content of ANF in coronary effluents were detected by radioimmunoassay (RIA). Results: Continuously stretching had no effect on heart rate and coronary flow of perfusing hearts. However, after 20 min of stretching, the levels of ANF in perfusates were significantly higher in stretch group(209.89±65.45 pg/ml)than in control group (108.84±25.18 pg/ml), and the levels of phospho-Akt in rat left ventricular myocardium were significantly higher in stretch group (0.76±0.03) than in control group (0.32±0.02), but there were no significant differences in total Akt between stretch group and control group. Conclusion: Mechanical stretch caused the augmentation of secretion of ANF, and the mechanism may be related to the activation of intracellular Akt signaling pathway.