Effect of glucagon on zinc excretion in anesthetized dogs

The present studies were performed on anesthetized dogs to determine whether urinary zinc excretion is altered when plasma glucagon concentration is elevated acutely. Glucagon infusion (5 ng.kg-1.min-1) adequate to double base-line plasma glucagon significantly increased zinc excretion in a reversible manner; plasma zinc concentration was unchanged. A larger dose of glucagon (50 ng.kg-1.min-1) produced no significantly greater effect. Clearance experiments using 65Zn to measure ultrafilterable zinc concentration revealed no change in ultrafilterable zinc during glucagon infusion. In a third series of experiments, acetylcholine (25 micrograms/min) was infused into one renal artery while zinc excretion and renal function of the two kidneys were compared. Acetylcholine did not significantly alter zinc excretion despite large changes in sodium and water excretion. The changes in zinc excretion observed in all experiments correlated well with glomerular filtration rate changes, but additional contributions of changes in tubular handling of zinc cannot be ruled out.