THE CARDIOVASCULAR EFFECTS OF RICIN IN RABBITS

Ricin is a toxic lectin from the castor bean. The time course of its t oxic effects on the cardiovascular system of rabbits was investigated after determining its LD(50) and minimum lethal dose in rabbits by the Up and Down method, as a basis for dosing. Systolic and diastolic art erial pressures, electrocardiogram and heart rate were recorded for 48 hr following administration of either a toxic sublethal (0.22 mu g/kg ) or minimum lethal dose (0.44 mu g/kg) of ricin. After a delayed onse t of about 20 hr, the minimum lethal dose (0.44 mu g/kg) of ricin caus ed a significant decrease in both systolic and diastolic pressures (P< 0.05). The systolic and diastolic pressures decreased 0.47 and 0.39 mm Hg/hr more so than control groups, respectively. A toxic sublethal dos e (0.22 mu g/kg) of ricin did not significantly alter either systolic or diastolic pressure. Neither dose of ricin caused cardiac arrhythmia s or significantly increased heart rate. We conclude that the lethal h ypotensive sequelae of ricin toxicity in the rabbit were peripheral in origin and not cardiogenic at these two doses.