A single exposure to cocaine or immobilization stress provides extremely long-lasting, selective protection against sudden cardiac death from tetracaine.

Exposure of rats to one injection of cocaine (35 mg/kg, i.p.) or a single four-hour period of immobilization protected them from the virtually instantaneous death but not from the later, seizure-related death seen in untreated controls following administration of the local anesthetic, tetracaine, 1-4 weeks later. These data suggest that when appropriately timed, strong sympathomimetic stimulation--whether generated by an environmental stressor or a drug--can provide long-lasting protection against the sudden cardiac death potential of local anesthetics. As such, they provide a means for understanding why the incidence of sudden cardiac arrest from one such agent--cocaine itself--is not higher and suggest that an individual's stress history may play a key role in determining vulnerability to the cardiotoxic effect of this compound.