Rates of Removal of Exogenous and Endogenous Glucagon From the Plasma of Sheep in Vivo

Abstract

The removal of exogenous and endogenous glucagon from plasma was determined in vivo in sheep weighing 53±1 (mean±s.e.) kg. Porcine glucagon was infused intravenously for 90 min. The metabolic clearance rates (MCR) were determined from plateau immunoreactive glucagon (IRG) concentrations in plasma and infusion rates of glucagon. The mean clearance rate (±s.e.) was 16·7±1·6 litres per hour (n = 20). Upon termination of the infusion, the decrease in IRG concentrations in plasma was determined. Least-squares regression analysis of non-linear functions indicated the data fit a two-component exponential function. The time constant for the rapid component of the plasma IRG disappearance function was -0·32±0·04 min-1 (mean±s.e.). The time constant for the slow component was -0·022±0·008 min-'. The rate of removal of endogenous glucagon was estimated during the infusion of somatostatin when glucagon secretion was inhibited. The time constants (mean±s.e., n = 8) for the decrease in IRG during somatostatin infusion were -0·42±0·08 and -0·003±0·002 min-' for fast and slow components, respectively. The time constants for the rapid components of exogenous and endogenous glucagon were not significantly different. This suggests that endogenous and exogenous glucagon are similarly removed from plasma.

Response of One‐Humped Camel (Camelus dromedarius) to Intravenous Glucagon Injection and to Infusion of Glucose and Volatile Fatty Acids, and the Kinetics of Glucagon Disappearance from the Blood

“…The distribution and elimination half-lives were 1.1909 2 0.0126 and 39.18 2 2.88 min, respectively. These times were shorter than those reported by De Boer et al (1986) for dairy cattle (5.0 2 0.24 and 110.0 2 30 min, respectively) and by Brockman (1980) for glucagon distribution in sheep (2.4 min). The elimination half-life in sheep, however, is reported by Brockman (1980) to be 23 min; a little shorter than in the camel.…”

“…These times were shorter than those reported by De Boer et al (1986) for dairy cattle (5.0 2 0.24 and 110.0 2 30 min, respectively) and by Brockman (1980) for glucagon distribution in sheep (2.4 min). The elimination half-life in sheep, however, is reported by Brockman (1980) to be 23 min; a little shorter than in the camel. The study revealed that glucagon is distributed with a large volume of distribution, 3.4005 l/kg (V c × 3 l/kg) and a high rate of clearance (18.03 2 0.12 l/kg/h).…”

Metabolism and Action of Insulin and Glucagon in Goat during Lactating and Dry Period

“…The metabolic clearance rates of glucagon were approximately 2.5 greater than those of insulin. They were apparently greater than the metabolic clearance rates of glucagon for dairy cows (10 ml/kg/min; DeBoer, Trenkle and Young 1986) and sheep (5 ml/kg/min; Brockman 1980). In these last studies the metabolic clearance rates of the hormone were calculated from both the rapid and slow decay curves whereas we only used the slow decay curve (see "Material and Methods").…”

Glucagon kinetics in growing rats fed different levels of protein and/or energy

“…4) Hoorn-Hickman, 1978 ;Brockman, 1980 ;Jaspan et al, 1981 ;Hayashi, 1982), but the apparent half-life and metabolic clearance rate values were respectively smaller (2 min vs 3-5 min) and higher (6 ml/min/100 g BW vs 0.5-1.5 ml/min/100 g BW) than those obtained in most works referred to. This discrepancy may be partially explained by the use of a pulse injection technique instead of a constant infusion technique.…”