Effect of CO2 Exposure and Respiratory Acidosis on Adrenal 17-Hydroxycorticosteroid Secretion in Anesthetized Dogs

Abstract

Effect of CO₂ exposure on adrenocortical function has been studied by measuring 17-hydroxycorticosteroids in adrenal venous blood of anesthetized dogs. In dogs exposed to 2.5%, 5% and 10% CO₂ successively for 1 hour each, and 10%, 20% and 30% CO₂ successively for 1 hour each, adrenocortical stimulation occurred in 10% of the total number of dogs exposed to 2.5% CO₂, 40% of the animals exposed to 5% CO₂, 75% of dogs exposed to 10% CO₂ and in all dogs subjected to 20% and 30% CO₂. Exposure to increasing concentrations of CO₂ was accompanied by a progressively severe respiratory acidosis. Dogs exposed to 20% CO₂ for 4 hours displayed a maximal adrenocortical stimulation within the first 15–30 minutes, and this marked response persisted for the remainder of the exposure period. The adrenocortical stimulatory response to 20% CO₂ exposure is abolished by hypophysectomy. It is concluded that the pituitary adrenal stimulation occurring in anesthetized dogs exposed to CO₂ is induced by one or more of the physiologic alterations attendant respiratory acidosis.