Heterogeneity of plasma glucagon immunoreactivity in normal, depancreatized, and alloxan-diabetic dogs.

Filtration of basal plasma from normal, alloxan-diabetic, and depancreatized dogs on Bio Gel P-10 yielded four glucagon-immunoreactive fractions. One of them appeared in the true glycagon area with the glucagon-125I (3500 mol vt). Of the other three, one appeared in the void volume (greater than 20000 mol wt), another just before the insulin-125I (congruent to 9000 mol wt), and the last one close to the salt peak (less than 2000 mol wt). The increase of total plasma glucagon immunoreactivity observed in depancreatized and alloxan diabetic dogs was mainly due to an increase in the 3500 and 9000 molecular-weight fractions. Arginine infusion in depancreatized dogs caused an increase in the 3500 molecular-weight fraction. Somatostatin or insulin infusion in depancreatized and alloxan-diabetic dogs resulted in disappearance of the 3500 molecular-weight fraction.