Deficient Activity of Hepatic Pyruvate Dehydrogenase and Pyruvate Carboxylase in Reye's Syndrome

Abstract

Summary: The activity of certain hepatic enzymes involved in carbohydrate metabolism was measured in postmortem samples from six cases of Reye's symdrome. The activities of the two exclusively extramitochondrial enzymes, glucose-6-phosphatase and fructose-1,6-diphosphatase, were all within the normal range. Activities of pyruvate carboxylase and pryuvate dehydrogenase, both of which are exclusively mitochondrial enzymes, were below levels shown by control tissue in every case, the average being 21.7% of the lowest control value for pyruvate carboxylase and 11.6% of that for pyruvate dehydrogenase. Impaired pyruvate metabolism appears to be another feature in Reye's syndrome. Speculation: The hypoglycemia and lactic acidemia frequently observed in Reye's syndrome are due to decreased activity in the mitochondria of pyruvate carboxylase and pyruvate dehydrogenase, respectively.