Postprandial Changes in Insulin Secretion Rates in Sheep

Abstract

Two experiments with sheep were conducted to measure disappearance from blood plasma of endogenous and exogenous insulin. Injected insulin disappeared with half-lives of 12.4 and 12.9 minutes in fed and fasted sheep, respectively. The calculated secretion rates were 0.66 µg/kg per hour after feeding and 0.13 µg/kg per hour after 48 hours of fasting. Injection of propionate or butyrate increased plasma insulin levels, which disappeared with a half-life of 14.0 minutes. The calculated secretion of insulin in response to the fatty acids varied from 60 to 90 µg per animal. It was concluded from these studies that the increase in plasma insulin levels occurring with feeding or injection of fatty acids is caused by a greater secretion rate of the hormone, rather than lower rate of disappearance from circulation or lower volume of distribution.