AJP - Gastrointestinal and Liver Physiology, Vol 253, Issue 2 110-G115, Copyright © 1987 by American Physiological Society
Glucagon and insulin metabolism in a portal-hypertensive rat model
E. Sikuler, J. Polio, R. J. Groszmann and R. Hendler
The role that portosystemic shunting plays in inducing the alterations of
glucagon and insulin metabolism, which are observed in chronic liver
disease, was studied in a rat model of prehepatic portal hypertension
induced by portal vein constriction. Net splanchnic output of the hormones
into the portal circulation was calculated from the difference between
portal and systemic concentrations multiplied by portal plasma flow.
Metabolic clearance rate was calculated as the ratio between output and
systemic concentration. Portal blood flow was measured by the radioactive
microsphere technique. Glucagon output in the portal vein-ligated rats was
higher than in the sham-operated controls (5.9 +/- 1.5 vs. 2.0 +/- 0.2
ng/min, P less than 0.05). The metabolic clearance rate of glucagon was not
significantly different between the two groups. Insulin output was not
significantly different between the two groups; however, the metabolic
clearance rate of insulin in the portal vein-ligated rats was reduced in
comparison with the sham-operated group (9.5 +/- 1.5 vs. 18.4 +/- 3.3
ml/min, P less than 0.05). Our results indicate that portosystemic shunting
per se is sufficient to cause an increased splanchnic output of glucagon
into the portal system and a decreased metabolic clearance of insulin.
