Effects of acute elevation of blood CO₂ tension on renal excretion of chloride and sodium by the anesthetized dog

¹ Department of Medicine, Postgraduate Medical School, New York University, New York City

Ten per cent carbon dioxide was administered acutely to anesthetized 15–20-kg dogs which had been loaded with varying quantities of hypertonic NaCl, hypertonic NaHCO₃ and, in some experiments, urea. In animals with low blood concentration and excretion rates of bicarbonate, CO₂ had no effect on sodium chloride reabsorption as measured at constant creatinine clearance. In animals with normal or elevated blood concentration together with significant excretion rates of bicarbonate, CO₂ resulted in a 5–7% increase in sodium chloride reabsorption. The effect on reabsorption was greater than predicted on the assumption that bicarbonate had depressed chloride reabsorption by acting as a simple osmotic diuretic and that CO₂, by enhancing bicarbonate reabsorption, had removed some of this osmotic diuretic agent.