低G预适应对重复+10Gz应激大鼠左心室收缩功能和心肌内皮素与前列环素含量的影响

Effects of Low-G Preconditioning on Contractive Ability of Left Ventricle and Contents of Endothelin and Prostacycline in Myocardium of Rats after Repeated +10 Gz Stress.

目的进一步验证低G预适应对 +Gz应激致心肌损伤的防护效应。方法 42只雄性Wistar大鼠随机分为 3组 (每组n =1 4) :A( + 1Gz)组、B( + 1 0Gz)组和C(低G预适应 )组。B组实验条件为 :+ 1 0Gz峰值暴露 30s ,5次 /d(间隔 + 1Gz 1min) ,3d/wk ,共 3wk ;A组仅受 + 1Gz作用 5min ;C组在每日+ 1 0Gz暴露前约 1h受 + 2Gz作用 5min ,其余处理同B组。于末次 +Gz实验后次日断头处死大鼠 ,速取心脏离体观察左室收缩压的变化 ;另取心肌组织测定其内皮素与前列环素含量。结果与A组相比 ,B组心肌收缩功能明显降低 ,心肌内皮素含量显著升高 ;而低G预适应使 + 1 0Gz应激大鼠左室收缩压明显增加 ,心肌内皮素含量明显降低。结论低G预适应对重复高G应激大鼠左室功能和心肌血管内皮细胞分泌功能均有一定的保护作用。

Objective To further test the protective effect of low-G pre-conditioning on +Gz stress induced cardiac damage. Method Forty-two male Wistar rats were randomly divided into 3 groups(n=14 for each group): group A(+1 Gz group), group B(+10 Gz group) and group C(low-G pre-conditioning group). The rats in group B were exposed to five +10 Gz plateaus of 30 s with 1 min intervals at +1 Gz, 3 times a week, for 3 weeks; while group A were only submitted to +1 Gz for 5 min.The rats in group C were exposed to +2 Gz for 5 min about 1 h prior to +10 Gz stress. All the animals were decapitated in the next day after the last centrifuge run and function of the isolated working hearts and contents of endothelin and prostacycline in the myocardium were observed. Result Compared with the control, a significant decrease of left ventricular systolic pressure(LVSP) and increase of myocardial contents of endothelin in rats were observed after repeated +10 Gz exposure; but low-G pre-conditioning could remarkably elevate the LVSP and reduce the myocardial endothelin level in rats after repeated +10 Gz stress. Conclusion Low-G pre-conditioning has a significant protective effect on contractive ability of the left ventricle and secretion function of the vascular endothelium in rat heart after high G stress.