Insulin is a physiological inhibitor of urinary zinc excretion in anesthetized dogs

Renal clearance experiments were performed on anesthetized dogs to determine the role of insulin in regulation of urinary zinc excretion. Intravenous infusion of somatostatin (2 micrograms/min) increased zinc excretion by approximately 100%, in association with 67% decreases in the plasma concentrations of both insulin and glucagon. Infusion of insulin (30 mU X kg-1 X min-1) along with the somatostatin maintained plasma insulin constant and completely eliminated the somatostatin-induced hyperzincuria; indeed, a small decrease in zinc excretion invariably occurred. Infusion of insulin alone (60 mU X kg-1 X min-1) decreased zinc excretion in five of six dogs. Plasma zinc concentration fell progressively, but to the same extent, throughout the experiment in all protocols. None of the hormonal infusions altered glomerular filtration rate, plasma concentrations of sodium, calcium, or magnesium or urinary excretion of these cations. We conclude that insulin, at physiological plasma concentrations, exerts an inhibitory effect on urinary zinc excretion.