Dimethoate-induced toxic cardiac failure in the guinea pig.

In anaesthetized guinea-pigs treated with lethal doses of dimethoate, cardiac failure and serious ECG disturbances developed in the early phase of intoxication. The toxic cardiac phenomena appeared to be unrelated to the degree of cholinesterase inhibition, but showed a close correlation with myocardial dimethoate concentration. Cardiac failure and mortality were first observed at a critical pesticide level of about 110 micrograms/g, while a level of 221 micrograms/g resulted in death in all cases. The present investigation refers to the direct effect of the pesticide on the myocardium, independent of its anticholinesterase action.