Abstract
Systemic arterial pressure changes caused by ephedrine, methamphetamine, tyramine, epinephrine and norepinephrine in chronically reserpinized dogs anesthetized with pentobarbital sodium after premedication consisting of morphine hydrochloride and atropine sulfate were studied in this experiment.In chronically reserpinized dogs, pressor action of ephedrine-like compounds was markedly suppressed while the action of epinephrine and norepinephrine were markedly potentiated. Subsequent norepinephrine infusion further reduced the reaction to ephedrine and methamphetamine; but only the action of tyramine was somewhat potentiated by infusion. When a certain dose of ephedrine or methamphetamine was given before norepinephrine infusion, however, no augmentation by tyramine was seen after infusion. When norepinephrine infusion was carried out at first, followed by ephedrine-like compounds for the first time, the pressor effect of all these drugs appeared more intense than in those without infusion. However, administration of cocaine before infusion almost completely suppressed such rise of blood pressure.
