STUDIES ON THE SYNTHESIS AND RELEASE OF ADENOSINE TRIPHOSPHATE-8-³H IN THE ISOLATED PERFUSED CAT ADRENAL GLAND

¹ Department of Pharmacology, West Virginia University School of Medicine, Morgantown, West Virginia

The perfused cat adrenal gland was able to take up and phosphorylate adenosine-8-³H. Stimulation of the gland with carbachol resulted in a simultaneous outpouring of catecholamines, adenosine-8-³H and phosphonylated nucleotides including a small quantity of labeled adenosine triphosphate (ATP). When the glands were perfused with a Ca⁺⁺-Mg⁺⁺-free medium to partially inhibit adenosine tniphosphatase, carbachol stimulation caused a considerable increase in the amount of the total released radioactivity represented by phosphorylated nucleotides. Under these conditions ATP-8-³H was the primary phosphorylated compound released. A radioactive compound tentatively identified as inosine was also found in the Ca⁺⁺-Mg⁺⁺-free effluents. A nucleotide analysis of adrenal glands showed that approximately 95% of the radioactivity retained in the gland after a single pulse injection of adenosine-8-³H was retained as phosphorylated nucleotides with ATP being predominant. The retained radioactivity represented approximately 1% of that injected. A direct demonstration of the presence of ATP-8-³H in relatively uncontaminated medullary granules was obtained by sucrose density gradient centrifugation. The above studies show that the synthesis, storage and release of ATP in the adrenal gland is a much more dynamic process than has hitherto been believed.