Sustained feeding or fasting affects levels of glucagon (IRG) in porcine plasma, gut and pancreas.

Arterial glucagon levels are elevated in fed pancreatectomised pigs and the source was sought by measuring the hormone in arterial, portal, hepatic and renal venous blood, and in gut tissues. Pigs which were starved for 48 hours (basal) were compared with sham operated or pancreatectomised pigs which were fed or starved for 7 days post operatively. Feeding of sham operated pigs caused a uniform increase in IRG 3485, while starvation resulted in a decreased portal IRG 7000. Pancreatectomy was associated with a uniform decrease in portal IRG 3485 and increase of IRG 7000 regardless of nutritional status. Hepatic and renal extraction of 23-26% was noted in fed animals (IRG 3485 in sham operated; IRG 7000 in pancreatectomised). In all starved pigs, hepatic and renal extraction were reduced to zero. The gastric and caecal mucosa and the pancreas contained most of IRG 3485. Gastric and caecal levels were increased after feeding of either group of animals, while fasting caused a marked increase in pancreatic IRG 3485 and a decrease in ileal IRG 7000. These studies demonstrate a direct effect of sustained nutritional status upon the distribution of glucagon in plasma and gastro intestinal tissues.