Inhibition of H+ secretion in frog gastric mucosa by somatostatin.

Somatostatin added to the serosal bathing solution of the isolated gastric mucosa of Rana pipiens significantly inhibited pentagastrin- and histamine-stimulated H+ secretion. The decrease in H+ secretion rate was accompanied by an increase in the transmucosal potential difference and resistance. Somatostatin (10(-5) M) had no effect on the N6,O2-dibutyryl adenosine 3'-5'-cyclic monophosphate (DBcAMP)-stimulated H+ secretion rate. The mucosa exposed to somatostatin secreted H+ on stimulation by DBcAMP or histamine, but did not respond to 2.8 X 10(-7) M pentagastrin. However, pentagastrin added to the serosal solution stimulated H+ secretion after the somatostatin was washed away. Calcium inophore (3 X 10(-5) M) alone or 10(-2) M Ca2+ plus calcium ionophore temporarily increased the H+ secretion rate inhibited by somatostatin. The data suggest that somatostatin has a direct effect on the oxyntic cells in the gastric mucosa.