Mitochondrial enzymatic alterations produced in the myocardium by anoxic cardiac arrest

Abstract

Normothermic anoxic cardiac arrest alters the activities of the mitochondrial enzymes in the myocardium. We have studied these alterations in 24 dogs. The animals were divided into three groups: Group I (control) consisted of 8 animals whose hearts were studied soon after anesthesia and thoracotomy. Group II included 8 dogs whose hearts were studied after being submitted to 60 minutes of anoxic arrest. The ascending aorta was clamped to produce anoxia. Group III was comprised of 8 dogs submitted to anoxic cardiac arrest for 60 minutes. The myocardium was then reperfused and cardiac activity was renewed before the hearts were studied. The following results were obtained: (1) The activity of succinic dehydrogenase, glutamic dehydrogenase, and beta hydroxybutyric dehydrogenase, in both simple and phosphorylating media, did not show statistically significant alterations after 60 minutes of anoxic arrest. (2) The activity of alpha ketoglutaric dehydrogenase in simple medium was markedly reduced by the anoxic arrest but returned to normal 60 minutes after coronary perfusion was resumed; in phosphorylating medium, however, its activity did not return to normal after cardiac recovery. (3) The activity of malic dehydrogenase in simple medium was markedly reduced by anoxic arrest and did not recover after renewed coronary perfusion.