Somatostatin Inhibition of Acid and Histamine Release by Activation of Somatostatin Receptor Subtype 2

Peptide analogs of somatostatin with relatively selective bind-ing affinities for specific somatostatin receptor subtypes, in-cluding SMS-201–995 [somatostatin receptor subtype (sst)2, sst3 and sst5], NC-8–12 (sst2), BIM-23058 (sst3) and BIM-23052 (sst5), were administered i.v. to anesthetized rats to determine the somatostatin receptor subtypes involved in reg-ulation of acid secretion stimulated by either pentagastrin (24 mg/kg/hr), bethanechol (0.2 mg/kg/hr) or histamine (5 mg/kg/hr) and in regulation of histamine release stimulated by either pentagastrin or bethanecol. Somatostatin-14 (10 nmol/kg/hr) inhibited pentagastrin-stimulated and bethanecol-stimulated acid secretion to basal levels but inhibited histamine-stimulated secretion to just 68 % of maximum. SMS-201–995 (10 nmol/kg/ hr) inhibited acid secretion similarly to somatostatin-14, indi