The effect of Bitis gabonica (gaboon viper) snake venom on blood pressure, stroke volume and coronary circulation in the dog

The effects of Gaboon Viper (Bitis gabonica) venom on cardiac output, arterial blood pressure, coronary flow and total peripheral resistance were investigated in eight anaesthetized dogs. Venom doses in the range of 0·125-0·50 mg/kg produced an abrupt fall in arterial blood pressure which recovered to near normal after 30 min. Stroke volume and cardiac output both rose during the hypotensive response and then declined to below control values. Heart rate and electrocardiogram were essentially unaltered. Coronary blood flow increased after venom and total peripheral resistance decreased. These responses tended to diminish as venom dose was increased, indicating some form of tachyphylaxis. The results indicate the presence of two different components affecting the cardiovascular system: a vasodilatory component responsible for the fall in peripheral resistance and hence arterial blood pressure and a cardiotoxic component responsible for the progressive reduction in stroke volume.