Effects of nimodipine, vinpocetine and their combination on isoproterenol-induced myocardial infarction in rats

Background: Myocardial infarction (MI) remains a major cause of morbidity and mortality worldwide. Nimodipine is a calcium (Ca2+) channel blocker as well as a PDE1 inhibitor and primarily used in subarachnoid haemorrhage (SAH) due to its blood-brain barrier crossing property. Nimodipine and vinpocetine inhibit the degradation of phosphodiester bond which increases cGMP and cAMP levels causing vasodilation. Material and methods: We have divided rats randomly into Group I-Vehicle control; Group II-Toxic control (ISO 85 mg/kg, i.p.); Group III, IV and V-Nimodipine (5, 10 and 15 mg/kg, i.p. respectively) with ISO; Group VINimodipine (15 mg/kg) alone; Group VII-Nimodipine + Vinpocetine (10 mg/kg + 10 mg/kg) with ISO; Group VIII-Nimodipine + Vinpocetine (10 mg/kg + 10 mg/kg) alone; Group IX-Diltiazem (25 mg/kg, p.o) with ISO; Group X-Diltiazem (25 mg/kg) alone and Group XI-Vinpocetine (10 mg/kg, p.o.) with ISO for 7 days. After 24 h of the last dose, haemodynamics were assessed then animals were sacrificed and biochemical, histopathological and ultrastructural changes were measured. Results: Treatment with ISO significantly deviated the haemodynamic parameters (HR, SAP, DAP and MAP), biochemical parameters (CK-MB, LDH, SGOT, cGMP and Troponin-T) and antioxidant markers (TBARS, SOD, CAT, GSH, GPx, GST and GR). Haemotoxylin and eosin staining of the cardiac tissue and ultrastructural study also indicated significant myocardial damage. Pretreatment with nimodipine (10 and 15 mg/kg, i.p), vinpocetine (10 mg/kg, p.o) and their combination significantly restored the antioxidant status, haemodynamic profile, cellular architecture and ultrastructural changes in the heart. Conclusion: Nimodipine and vinpocetine both showed cardioprotection when given alone. However, their combination showed better restoration in terms of oxidative stress, cardiac membrane damage, haemodynamics, histopathology and ultrastructural changes.