Glucose-6-phosphate dehydrogenase of adrenal tissue.

The direct oxidative pathway of glucose utilization or the hexose monophosphate shunt has received a great deal of attention recently, and numerous attempts have been made to evaluate its importance in various tissues. Glock and McLean, in making a survey of the levels of enzymes of this pathway in a number of mammalian tissues, recently reported unusually high activity in the adrenal glands, particularly in the adrenal cortex (1). This paper reports the results of an investigation of carbohydrate metabolism in adrenal tissue which also led to this finding. At the time this investigation was started, the knowledge of carbohydrate metabolism in the adrenal gland was limited to the observation that a glycolytic system could be obtained from adrenal tissue (2, 3) and that certain intermediates of the tricarboxylic acid cycle could be oxidized by the adrenal gland (4, 5). Evidence is presented in this report for the existence of two different pathways of glucose utilization in adrenal tissue. Besides the glycolytic pathway, there is shown to be a very active alternative pathway which proves to be the hexose monophosphate shunt. The cyclic nature of this pathway is indicated in adrenal systems as it has been previously in other tissues. A comparison is given of the glucose-6-phosphate dehydrogenase levels of a number of mammalian tissues, and Glock and McLean’s report of the unusually high activity in adrenal cortex is confirmed. A preliminary report of this work was presented earlier (6).