Plasma glucagon-like immunoreactivity (GLI) in dogs

Gut glucagon-like immunoreactivity (GLI) was extracted from plasma of dogs and was compared for its molecular size and insulin releasing activity with GLI present in the intestine. Plasma was obtained from the portal vein of dogs, of which the pancreas was removed as rapidly as possible during the glucose administration into the intestine. Plasma GLI of intestinal origin was extracted by a modification of Kenny's method. The amount of GLI extractable from plasma in each dog ranged from 4.30 to 25.74 ng. The extract of plasma during glucose absorption was observed to have two peaks on gel filtration, corresponding to Peak I and Peak II of GLI extracted from the gastrointestinal tract. The intrapancreatic infusion of the Peak II GLI extractable from plasma promoted remarkable insulin release in dogs, like pancreatic glucagon. In contrast, the Peak I GLI from plasma caused an equivocal rise of insulin in the pancreatic vein. It is concluded from the experiment that gut GLI extracted from plasma shows the same elution pattern on gel filtration and the same insulin releasing activity as GLI extractable from the gut.