Oxidative stress and expression of heme oxygenase-1 mRNA in the myocardial tissue of rats after limb ischemia/ reperfusion injury / 中华急诊医学杂志

ABSTRACT

Objective To study the mechanism of oxidative damage in myocardial tissue after limb ischemia reperfusion (IR), and the protective effects of heme oxygenase-1 on myocardial injury in experimental rats. Method The models of bilateral hind limbs ischemia and reperfusion in rats were established by using tourniquets applied to the roots of both hind limbs until palm blanched and pulseless for 4 hours. A total of 56 SD rats were randomly (random number) divided into 7 groups, namely one normal control group ( n = 8) and 6 ischemia-reperfusion groups as per different lengths of reperfusion time, e. g. 2 hrs, 4 hrs, 8 hrs, 16 h rs and 24 hr ( n = 8 each). The experimental rats were sacrificed after different lengths of reperfusion time. Specimens of myocardium and blood were taken for assays of malonaldehyde (MDA), superoxide dismutase (SOD) and myeloperoxidase (MPO), and pathological changes of myocardium were observed, and the expressions of HO-1 mRNA in myocardium were detected. Data were analyzed with ANOVA. Results (1) Compared with the control group, the levels of serum MDA and myocardial MDA of rats were increased in all IR groups and were higher (P < 0.05), and the levels of MDA reached the peak after reperfusion for 4 hours. The levels of serum SOD and myocardial SOD in rats of all IR groups were decreased and lower than those in rats of the control group ( P < 0.05), and the levels of serum SOD dropped away to the lowest point after reperfusion for 4 hours, and the levels of myocardial SOD fell off to the bottom after reperfusion for 8 hours. The levels of serum MPO and myocardial MPO were significantly increased in rats of all IR groups compared with the control group (P < 0.05). The levels of serum MPO reached peak after reperfusion for 4 hours, and the levels of myocardial MPO were increased to the highest spot after reperfusion for 6 hours. (2) The pathological changes in myocardium showed the most severe damage after reperfusionfor 4-6 hours.(3) After reperfusion for 2 hours, there were no significant differences in the expression of HO-1 mRNA between IR groups and control group (P >0.05), and after reperfusion for 4 hours and over, the expressions of HO-1 mRNA were markedly increased in IR groups and reached peak after reperfusion for 16 hours in comparison with the control group (P < 0.05). Conclusions The activation of neutrophils and free radicals may play a primarily adverse role in myocardial injury after limb IR, and the increase in the expression of HO-1 mRNA lessens the harm effects of IR on myocardium.