The response of pancreatic and pituitary hormones to pulses and constant infusion of somatostatin.

The inhibitory action of pulses and constant infusion of somatostatin on the secretion of pancreatic and pituitary hormones was studied serially in 7 normal men and 2 untreated acromegalics. In normal men, significant inhibition of basal release of insulin and glucagon was elicited by as little as 1 mug dose of a pulse of somatostatin. Increasing doses of somatostatin (5, 50, 250 and 500 mug) given as a single pulse at weekly intervals produced what appears to be a decreased inhibition of glucagon while no measurable relationship between the dose of somatostatin and the degree of inhibition of insulin was seen. Given during the same day, incremental doses (from 1 to 250 mug) of pulses of somatostain produced a progressive decline in both glucagon and insulin. The elevated basal levels of GH, insulin and glucagon seen in acromegalics, were inhibited by a pulse of somatostatin as little as 2 mug. These inhibitions were sustained during the constant infusion of somatostatin (2.5 mug/min), and a rebound in GH, insulin and glucagon appeared promptly following the infusion.