Inhibition of growth hormone and glucagon release by Phe-4-somatostatin in patients with acromegaly.

We have studied growth hormone (GH), insulin (I), glucagon (Gl) and glucose in basal conditions, after somatostatin (SS) (3 micrograms/ml) and Phe-4-SS (0.75 microgram/ml) infusion and IV bolus of the latter in 3 acromegalic patients. In two patients, Phe-4-SS inhibited glucagon and growth hormone secretion in a similar way as SS, without modifying insulin secretion. These effects were short-lived and ceased after the infusion was stopped. From these results it appears that Phe-4-SS is both more potent and more specific than SS with respect to inhibition of GH and glucagon release, but it does not have prolonged biological action. Lack of suppression of GH by SS or Phe-4-SS in the acromegalic patient with post-surgical recurrence of the disease could be due to the existence of receptor abnormalities, and suggests a diversity in the physiopathology of the disease.