1976 Volume 23 Issue 3 Pages 187-193
Ten healthy male volunteers were studied to compare the effectiveness of intravenous and subcutaneous injections of 1mg of glucagon on HGH secretion. Plasma HGH level rose to a peak of 6ng/ml or greater 120 minutes after the subcutaneous injection of glucagon (sc glucagon) in all subjects, whereas the intravenous injection of glucagon (iv glucagon) caused comparable increments in plasma HGH in only six out of ten subjects. Furthermore, in comparison to those in sc glucagon the periods required to show maximum responses were less consistent in iv elucazon. Plasma IRG levels reached a peak of 102.4±22.6ng/ml at two minutes following iv glucagon, and a peak of 3.33±1.08ng/ml at 15 minutes following sc glucagon. These fell to initial levels at 60 minutes and at 180 minutes, respectively. There was no definite correlation either between the magnitudes of changes in plasma IRG and HGH levels or between the velocities of decrement in blood sugar and HGH responsiveness. Judging from its simplicity and reproducibility it may be concluded that sc glucagon is more suitable for a clinical provocative test of HGH release than is iv glucagon. In regards to the mechanism of glucagoninduced HGH release, neither glucagon per se nor the fall of blood sugar after hyperglycemia was assumed to play any major role. The sustained elevation of plasma IRG for a certain period might be responsible for the glucagon-induced HGH release.
