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

Abstract

Summary. The (-25 %). In all cases, the animals were fed a meal every 4 hours.The kinetic parameters of glucagon metabolism were estimated from the plasma disappearance curves of 125 1-glucagon for five minutes following a pulse injection of purified ' z5 1-glucagon (1 A Ci, about 3.8 ng/100 g BW). Plasma ' 25 1_glucagon was measured after gel filtration of plasma on Biogel P-10. Tissue radioactivity (mainly liver and kidneys) was recorded seven minutes after ' z5 1-glucagon injection.The results showed that the plasma ' z5 1-glucagon level was higher in Group H than in the other groups 1 min after the injection. At all other times (2, 3.5 and 5 min) it was similar in all groups. ' z5 1-glucagon was rapidly cleared from plasma and rapidly taken up by the liver and kidneys. In the 3 experimental groups, mean half-life and metabolic clearance rate were estimated to be 2 min and 6 ml/min/100 g BW, respectively. Excess protein intake resulted in a reduction in the apparent initial distribution volume of ' z5 1-glucagon without modifying significantly its turn-over rate and metabolic clearance rate. Kidneys and liver (6 % BW) accounted for about 20 % of the ' z5 1-glucagon uptake by tissues 7 min after injection. Group H kidneys and liver were more labelled than in other groups. These results suggest that increased protein intake (without further caloric deprivation) can induce some changes in glucagon metabolism which could partially contribute to the increase in glucagonemia usually observed in animals fed high protein diets.Introduction.

Normal Glucagon Signaling and β-Cell Function After Near-Total α-Cell Ablation in Adult Mice

“…This suggests that the intracellular glucagon store in the remaining α-cells is, in principle, sufficient to maintain basal glucagonemia. However, because plasma glucagon has a half-life of only 2 min (20–22), sustained glucagon biosynthesis after α-cell ablation is mandatory to maintain glucagonemia and pancreatic content over time. Indeed, in absence of glucagon biosynthesis, all pancreatic glucagon stocks found after DT should theoretically be finished within ∼6 h vs. ∼17 days in control mice with normal α-cell mass (estimated considering the observed pancreatic glucagon contents and glucagon half-life).…”

Relationship between plasma glucagon disappearance and tissue uptake in rats

“…1, inset) (Balage and Grizard, 1984). It was associated largely with two organs, the liver and the kidneys, confirming that they are the primary sites of glucagon removal from the plasma (Jaspan et al, 1981 ;lshida et al, 1983).…”

“…-Plasma !z51-glucagon was determined as described previously (Balage and Grizard, 1984 (Balage and Grizard, 1984), plasma radioactive material eluted mainly as 4 peaks ( fig. 2) from the Biogel P 10 column.…”