Sympathetic cardiovascular effects of experimental strychnine poisoning in dogs.

The cardiovascular effects of intravenously administered strychnine were studied in anesthetized and paralyzed dogs. Administration of strychnine in cumulative doses of up to 0.1 to 0.2 mg/kg caused significant pressor, as well as positive inotropic and chronotropic, effects on the heart which were abolished by adrenergic blocking agents. The cardiovascular responses possibly were elicited by a central mechanism in contrast to the peripheral inhibitory action of strychnine on the sympathetic system. Diazepam caused a marked attenuation of the pressor response with only slight changes on the heart. A combination of diazepam and propranolol would appear to be a useful therapy in cases of strychnine poisoning showing marked cardiovascular excitation.