This research program is concerned with the regulation of metabolism by drugs, ions and hormones. We propose to study the mechanisms involved in the regulation of glycogen synthesis in skeletal and cardiac muscle and the role of nucleotides in influencing the turnover of glycogen in these tissues. Studies will be continued on the mechanism by which lithium ions stimulate glycogen synthesis and inhibit the action of epinephrine in activating adenylate cyclase. Finally, we plan to investigate the actions of ephinephrine and phosphodiesterase inhibitors in causing an inhibition of glucose uptake by skeletal muscle incubated in vitro in order to determine the role that cyclic AMP may play in this phenomenon. BIBLIOGRAPHIC REFERENCES: E.S. Haugaard, S. Davidheiser and N. Haugaard. Effects of epinephrine and cyclic AMP phosphodiesterase inhibitors on the glycogen synthetic pathway and glucose content in skeletal muscle. Biochem. Pharmacol. 25: 439-445, 1976. R.M. Levin, N. Haugaard and M.E. Hess. Opposing actions of calcium and magnesium ions on the metabolic effects of epinephrine in rat heart. Biochem. Pharmacol. 25: xxx, 1976.