Acidosis induced by catecholamines and reduction of cardiovascular responses to catecholamines in acidosis.

Abstract

SummaryInfusions of the catecholamines noradrenaline, adrenaline and isoprenaline in anaesthetized rats under artificial ventilation caused a fall in arterial blood pH and a slight rise in PCO2. The order of potency of the catecholamines in producing metabolic acidosis was isoprenaline > adrenaline > noradrenaline. This effect of isoprenaline was abolished by propranolol but was not changed by phenoxybenzamine. The effect of noradrenaline was abolished by phenoxybenzamine and was potentiated by propranolol. The decrease in cardiovascular responses to catecholamines that follows an infusion may be partly due to the resultant acidosis, since acidosis produced by infusions of hydrochloric acid resulted in decreases of the responses of the heart and blood pressure to noradrenaline and isoprenaline. The decreased cardiovascular responses caused by catecholamine infusions were partly restored when the blood pH was returned to normal levels by administration of Tris buffer.