Renal Response to Hypercapnia.

Abstract

An avg. increase of 17.9 vol. % in arterial blood CO2 concn. was produced in dogs by rebreathing from a spirometer. No evidence of significant renal vasomotor alteration was noted. However, urinary pH decreased, and Na excretion progressively decreased to an avg. of 35% of control. Thus, elevated H+ concn. of the blood had in some manner enhanced the tubular reabsorption of Na. K excretion also diminished, presumably due to depressed tubular secretion by the predominance of H+ made increasingly available for exchange with Na. Plasma concn. of K increased during hypercapnia, due to renal retention or mobilization from the intracellular compartment. Plasma Na 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 K and Na beyond control averages.