Effects of sand viper ( Cerastes cerastes) venom on isolated smooth muscle and heart and on haematological and cardiovascular parameters in the guinea-pig

The effects of the venom of the sand viper ( Cerastes cerastes) on haematological and cardiovascular parameters and on isolated ileum, trachea, pulmonary artery and atrium from the guinea-pig were studied. In concentrations from 0.2 μg/ml to 0.6 mg/ml, snake venom caused concentration-dependent relaxation of the longitudinal ileal segments and the epinephrine-precontracted pulmonary artery rings, increased the tone of the tracheal rings and increased the rate of the spontaneously beating atrium but depressed the amplitude of its contraction. Low doses (0.04–0.4mg) of the venom caused transient small depression of both heart rate and contractility of the isolated perfused heart. A higher dose (1.0 mg) significantly inhibited both parameters and delayed their recovery. An i.v. injection of 0.12 mg/kg of the snake venom to anaesthetized guinea-pigs had no effect on red blood cell count, haemoglobin concentration or the haematocrit value but significantly reduced the circulating white blood cells, the plasma clotting time and erythrocyte deformability. Also, i.v. injections of 0.02–0.2 mg/kg of the venom caused initial depression of the systolic and the diastolic blood pressure followed by complete or partial recovery and subsequent hypotension. These observations indicate that C. cerastes venom has multiple sites of action which may help in better understanding the pathology of bites by this snake.