Kinetics of somatostatin inhibition of pentagastrin-stimualted gastric acid secretion.

Dogs with gastric fistulae and denervated gastric pouches received graded doses of pentagastrin with and without a background infusion of somatostatin (1 microgram kg-1 h-1). Similarly, graded doses of somatostatin (0.25, 0.5, 1, 2 and 4 microgram kg-1 h-1) were infused after a steady state gastric secretion had been achieved with pentagastrin (1.5 microgram kg-1 h-1), about twice the dose required to produce half maximal (D50) response. Somatostatin inhibited pentagastrin-stimulated gastric acid secretion with competitive inhibition kinetics, but its precise site of action remains uncertain. The minimum effective dose of somatostatin on a twice D50 dose of pentagastrin was 0.25 microgram kg-1 h-1.