Estimates of the Kinetic Parameters of Growth Hormone Metabolism in Fed and Fasted Calves and Sheep

Publisher Website
Google Scholar
Abstract
The metabolic clearance rate of growth hormone was determined in castrated male sheep by using a constant infusion and a single injection of pituitary growth hormone. The mean values obtained were 8.0 ± .9 and 11.0 ± 1.2 liters/hr with the constant-infusion and single-injection techniques, respectively. The rate of disappearance of injected growth hormone from plasma was measured in eight sheep at 2.5 hr after feeding and in seven sheep 48 hr after feeding. Similar experiments were conducted with six bull calves at 4 hr after feeding and with three bull calves at 23 hr after feeding. Concentrations of plasma glucose and insulin were significantly (P<.01) lower in the fasted animals. Plasma growth hormone concentrations were not significantly elevated during fasting. Fasting increased (P<.01) the half-life of the injected growth hormone from 9.2 to 13.4 min in sheep and from 20.3 to 31.9 min in calves. The volume of distribution of the immunologically reactive growth hormone was about 6 and 8% of the body weight in calves and wethers, respectively, and was not influenced by fasting. Calculated secretion rates of growth hormone were .8 µg/kg/hr in both the fed and fasted sheep and 2.6 and 1.8 µg/kg/hr in fed and fasted calves, respectively. Copyright © 1976. American Society of Animal Science . Copyright 1976 by American Society of Animal Science

This publication has 1 reference indexed in Scilit: