Comparative effects of acidosis induced by acid infusion and CO₂ accumulation

¹ Department of Cardio-Respiratory Diseases, Walter Reed Army Institute of Research; and Department of Physiology, George Washington University School of Medicine, Washington, D.C.

Thirteen dogs were paralyzed with succinylcholine and ventilated at constant rate and volume with 100% O₂. The control animals were given an i.v. infusion of .15–.30 m lactic acid at the rate of .33 mm/kg/min. for the first 30 minutes and at the rate of .16 mm/kg/min. for the following 30 minutes. After 1 hour pH had fallen from 7.39 to 7.00, diuresis was maintained and mean blood pressure, catecholamine and glucose blood levels were unchanged. By contrast animals with a similar fall in pH produced by CO₂ retention presented signs of marked stimulation of the sympatho-adrenal system, such as increased blood pressure, anuria, elevated catecholamine and glucose blood levels. These data indicate the importance of intracellular [H⁺] changes in the regulation of circulation. The fixed ‘addition acidosis’ produced by lactic acid infusion as described, was corrected by an i.v. infusion of .33 mm/kg/min. of .33 m tris(hydroxymethyl) aminomethane (THAM) which was administered during the second 30-minute period of lactic acid infusion. A similarly produced acidosis required for correction an amount of bicarbonate of sodium double that of THAM.