[Effects and mechanisms of heme oxygenase-1 on rats with postresuscitation myocardial dysfunction]

Abstract

Objective: To explore the effects and mechanisms of heme oxygenase-1 on rats with postresuscitation myocardial dysfunction.

Methods: Male Sprague-Dawley rats were asphyxiated for 9 minutes and resuscitated. They were randomly divided into 4 groups: sham-operated, cardiopulmonary resuscitation (CPR), hemin and hemin + ZnPP (zinc protoporphyrin IX). Resuscitated groups had 2 observation points: 6 and 24 hours post-CPR (n = 8 for each time point). And the sham-operated group of 12 rats were divided in two observation points, according to 6 or 24 hours post-operation (n = 6 each). Hemodynamic was observed. The expression of heme oxygenase-1 (HO-1) in cardiac tissue was detected by Western blot. And the activity of cardiac homogenate superoxide dismutase (SOD) was determined by xanthine oxidase method and the level of malondialdehyde (MDA) measured by the thiobarbituric acid method. Nitrotyrosine protein expression in cardiac tissue was analyzed by immunohistochemistry.

Results: (1) The mean blood pressure (MAP) significantly decreased in resuscitated groups after resuscitation (all P < 0.05). No difference existed between the subgroups. The scores of dP/dt40 and -dP/dt significantly decreased in CPR and hemin + ZnPP groups after resuscitation (all P < 0.05). But dP/dt40 in hemin group did not differ significantly after resuscitation and -dP/dt decreased only 0.5 hour and 1 hour post-resuscitation (3341.60 ± 524.85 and 3711.40 ± 502.39 vs 4284.20 ± 800.87, all P < 0.05). The scores of dP/dt40 and -dP/dt in hemin group at all time points post-resuscitation were significantly higher than those in CPR and hemin + ZnPP groups (all P < 0.05). (2) Compared with the sham-operated group, the HO-1 expression, MDA level and nitrotyrosine protein expression significantly increased while the activities of SOD decreased after resuscitation in the CPR, hemin and hemin + ZnPP groups (all P < 0.05). Compared with the CPR and hemin + ZnPP groups, the expression of HO-1 and the activity of SOD increased, while MDA level and nitrotyrosine protein expression were decreased in group hemin (all P < 0.05). No difference existed in the above indices between the CPR and hemin + ZnPP groups.

Conclusion: HO-1 can reduce myocardial oxidative stress injury after cardiopulmonary resuscitation and effectively improve post-resuscitation myocardial function in rats.