Renal Response to Hypercapnia. ∗

Abstract

Summary

An average increase of 17.9 volume % in arterial blood CO₂ concentration was produced in dogs by rebreathing from a spirometer. No evidence of significant renal vasomotor alteration was noted. However, urinary pH decreased, and sodium excretion progressively decreased to an average of 35% of control. Thus, elevated H+ concentration of the blood had in some manner enhanced the tubular reabsorption of sodium. Potassium excretion also diminished, presumably due to depressed tubular secretion by the predominance of H+ made increasingly available for exchange with sodium. Plasma concentration of potassium increased during hypercapnia, due to renal retention or mobilization from the intracellular compartment. Plasma sodium showed a similar trend. Hyperventilation occurred for a time on return to room air. This phase manifested a decrease in blood CO₂, increase in urinary pH, and increase in the excretion of potassium and sodium beyond control averages.