Metabolic effect of pH on myocardium of heart-lung preparation

Cardiac performance and metabolism of heart-lung preparation of rat were studied with acid, normal, and alkali perfusions. Cardiac output, glucose uptake, and myocardial content of lactate, malate, glycerophosphate, and CP were increased in alkali and decreased in acid perfusion of 20 min. On the other hand, when pH of the perfusate was abruptly changed, CP and ATP were decreased independent of the performance. FDP was high and PEP was low in acute acidifying experiments. From these findings it is concluded that cardiac performance and carbohydrate metabolism are accelerated in alkali and depressed in acid perfusion, and that myocardial metabolism could be affected by pH not only secondary to the change of performance but also by itself.