Effects of rat amylin on renal function in the rat

Amylin is a peptide secreted from the pancreatic beta-cell along with insulin in response to nutrient stimuli. Amylin has been reported to delay gastric emptying, inhibit glucagon secretion and gastric acid secretion, increase plasma lactate, plasma glucose and plasma renin activity, and decrease plasma calcium. Receptors for amylin have been found in the rat nucleus accumbens and the kidney. In the present experiments, amylin was administered to anesthetized rats by continuous intravenous infusions at varied rates. Amylin significantly increased urine flow at an infusion rate resulting in a plasma concentration of approximately 52 pM, and at a concentration of approximately 193 pM, it increased sodium excretion, glomerular filtration rate and renal plasma flow. Renal calcium and potassium excretion were significantly elevated at plasma amylin concentrations of approximately 52 pM and 193 pM, respectively. Higher concentrations of plasma amylin decreased plasma calcium and potassium and blunted urinary excretion of these electrolytes. Thus, of the renal responses tested, diuresis and natriuresis appeared to be the most sensitive to infused amylin. These renal effects occurred only at plasma concentrations above the normal range, but within the range of concentrations reported in insulin resistant rats.