Abstract

Studies are reported on normal and adrenalectomized dogs directed toward evaluating the role of the adrenal medulla in the blood pressure response to intravenously injected nicotine. The results indicate that with small to moderate doses of nicotine, release of epinephrine from the adrenal medulla contributes substantially to the pressor response obtained. Following nicotine paralysis of the vasomotor components of the nervous system, marked pressor responses can still be obtained on further injection of nicotine and these are presumably due solely to release of epinephrine.

Additional findings include the fact that the pressor action of epinephrine is potentiated by moderate amounts of nicotine, possibly resulting from at least partial paralysis of the parasympathetic ganglia. Furthermore, in chronically adrenalectomized dogs in apparent good health, injection of epinephrine, ephedrine or acetylcholine may result in a profound and prolonged fall in blood pressure.