Gastric secretion and gastrin under progressive doses of somatostatin-14 and -28 administered intraperitoneally to the rat.
The actions of progressive doses of intraperitoneally (IP) administered somatostatin-14 (SS-14) and -28 (SS-28) on gastric secretion (acid, pepsin) and mucosal blood flow (MBF) were studied in conscious gastric fistula rats both under basal conditions and under additional administration of pentagastrin. Also, somatostatin-like immunoreactivity was measured in aortal blood in all groups as well as aortal gastrin levels under basal conditions. IP infusion of equimolar doses of SS-14 and SS-28 resulted in an equal and dose-dependent inhibition of basal as well as pentagastrin-stimulated gastric acid secretion. MBF was reduced by either peptide both in the basal and pentagastrin experiments. Under basal conditions pepsin secretion was significantly increased by infusion of SS-14 at the higher doses, by infusion of SS-28 only at the intermediate dose (3.1 nmole kg-1.hr-1). In the pentagastrin experiments, low and intermediate doses of SS-14 tended to lower pepsin outputs but the highest dose of SS-14 stimulated pepsin secretion, whereas SS-28 had no effect on pepsin. Administration of SS-28 inhibited gastrin only at the highest dose (12.3 nmole kg-1.hr-1), and SS-14 had no influence at all on gastrin. After IP infusion of both peptides, plasma SLI rose dose-dependently under basal and stimulated conditions. Gel chromatography indicated an in-vivo conversion of SS-28 to SS-14 or intermediate fragments. It is concluded that SS-14 and SS-28 delivered by IP infusion, inhibit basal and stimulated gastric acid equally in the rat without suppressing gastrin. The mechanism underlying SS-mediated pepsin stimulation is unknown.
D000818:Animals; D005744:Gastric Acid / Q000378:metabolism*; D005753:Gastric Mucosa / Q000187:drug effects / Q000378:metabolism*; D005755:Gastrins / Q000097:blood / Q000378:metabolism*; D007274:Injections, Intraperitoneal; D008297:Male; D010418:Pentagastrin / Q000494:pharmacology; D010434:Pepsin A / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains; D012016:Reference Values; D013004:Somatostatin / Q000008:administration & dosage / Q000494:pharmacology*; D053561:Somatostatin-28
D005755:Gastrins; D013004:Somatostatin; D053561:Somatostatin-28; D010434:Pepsin A; D010418:Pentagastrin