Kleinhovia Hospita Leaf Extract Protects the Heart Against Infarction by Isoproterenol

Abstract

Background: Isoproterenol, a β-adrenergic agonist, may induce myocardial infarction when used in high dosage in rats. This study was conducted to evaluate the effect of the ethanol extract of Kleinhovia hospita leaves on cardiac biomarkers and myocardial structures of rats induced by isoproterenol. Methods: Male rats (n=30) were assigned as a normal controls or treatment groups. The treatment groups received pretreatments, either placebo or the extract at doses of 250, 500, or 750 mg/kg for 14 days, followed by two isoproterenol injections at 100 mg/kg. After 24 hours, blood samples were taken and the hearts dissected. The tested cardiac biomarkers were creatinine kinase myocardial band (CKMB) and lactate dehydrogenase (LDH). Heart histopathology analysis was performed followed by staining of samples with hematoxylin and eosin. Results: The isoproterenol injections significantly increased CKMB and LDH levels in the placebo group compared to those in normal controls. Pretreatment with the extract at doses of 500 and 750 mg/kg significantly reduced the serum CKMB and LDH levels compared to those of the placebo. The histopathological examinations showed the presence of diffused necrosis and severe inflammation in the placebo group. Pretreatment with the extract at 500 or 750 mg/kg significantly reduced the myocardial tissue damages in rats. Conclusion: The K. hospita extract at doses of 500 or 750 mg/kg significantly reduced the infarctions in the rats’ heart tissue, shown by significantly low levels of CKMB and LDH, and reduced necrotic lesions and inflammation in the rat heart tissue samples induced by isoproterenol pretreatment.