Cardioprotective actions of ascorbic acid during isoproterenol-induced acute myocardial infarction in rats.

BACKGROUND/AIMS: In the present study, we tested whether or not acute antioxidant treatment with vitamin C is able to protect the heart during myocardial infarction. The effects of vitamin C on the autonomic balancing of the heart and on the histopathological and immunohistochemical changes in response to isoproterenol administration (ISO) were evaluated.

METHODS

Four groups of male Wistar rats (n = 32) were studied: control; ISO treated; vitamin C treated; ISO + vitamin C treated. ISO 150 mg/kg was administered for 2 consecutive days. Vitamin C (250 mg/kg, oral) was administered 30 min before each ISO treatment. Phenylephrine and sodium nitroprusside were administrated to increase or decrease blood pressure in conscious rats.

RESULTS

The baroreceptor reflex index for bradycardia was significantly reduced in the ISO group (control, -3.4 +/- 0.3 beats/mm Hg; ISO -2 +/- 0.4 beats/mm Hg) and vitamin C treatment significantly improved the reflex index (-2.9 +/- 0.7 beats/mm Hg). Treatment with vitamin C showed mild degenerative changes in the myocardial tissue of the ISO group. The antioxidant was able to decrease the inducible nitric oxide (iNOS) expression in rats treated with vitamin C.

CONCLUSION

Vitamin C administration proved to be effective in reducing the extent of myocardial damage during ISO-induced myocardial infarction in rats associated with an iNOS downregulation and improving the autonomic balancing of the heart.