THE EFFECT OF HYPERCAPNIC ACIDOSIS UPON SOME GLYCOLYTIC AND KREBS CYCLE‐ASSOCIATED INTERMEDIATES IN THE RAT BRAIN

Abstract

Abstract— In order to study the influence of intracellular pH on the carbohydrate metabolism of brain tissue, the concentrations of glucose, glucose‐6‐phosphate, pyruvate, lactate, citrate, α‐oxoglutarate, malate, glutamate, aspartate and ammonia were measured in rats exposed to 6–40% CO 2 , for 45 min. Hypercapnia of increasing severity gave rise to progressive increases in the concentrations of glucose, glucose‐6‐phosphate and ammonium ion and to progressive decreases in the concentrations of all metabolic acids measured. The results fit with aH + inhibition of a rate‐limiting step between glucose‐6‐phosphate and pyruvate, and by inference from the results published by others it may be assumed that this step is the phosphofructokinase reaction. Since the proportionally largest decrease occurred in a α‐oxoglutarate, the results might be compatible either with an inhibition of a second rate‐limiting step such as isocitrate dehydrogenase, or with a loss of α‐oxoglutarate through carboxylation to citrate.