Pretreatment with tetrandrine has protective effects against isoproterenol-induced myocardial infarction in rabbits

Tetrandrine, the active principle of Stephania tetrandra radix extracts, has broad pharmacological activity, including effects on the cardiovascular system: it has been shown to reduce the size of acute myocardial infarction in rats undergoing coronary vessel ligation and to improve heart lesions in the constriction/reperfusion model by means of mechanisms involving peroxidation, calcium antagonism and coagulation. The aim of this study was to investigate whether tetrandrine has anti-infarction, antioxidant and anticoagulant effects in rabbits treated with isoproterenol, a drug capable of causing peroxide generation, calcium overload and coagulation alterations, and inducing myocardial infarction. The results showed that pretreatment with tetrandrine protects against the myocardial injuries caused by isoproterenol. It counteracted the appearance of myocardial necrotic lesions and ischemic electrocardiographic modifications, such as ST segment alterations, prevented the appearance of the plasma cardiac necrosis markers c-troponin I and myoglobin, lowered malondialdehyde levels, and prolonged partial thromboplastin time. The protective effects of tetrandrine can be attributed to its antioxidant action in lowering peroxide levels and its ability to counteract coagulating activity. Tetrandrine seems to offer full protection against myocardial infarction experimentally induced by the non-invasive treatment of rabbits with isoprotenerol.