Effect of somatostatin on basal and stimulated gastric secretion in the cod, Gadus morhua

In vivo secretion of gastric acid and pepsin has been studied in pylorus-ligated cod. Basal acid output amounted to 100-150 mumol H+.kg-1.h-1 and pepsin secretion to 1 mg.kg-1.h-1. In response to bombesin nonapeptide (2.4 nmol.kg-1.h-1) and histamine (81 nmol.kg-1.h-1), acid secretion increased to approximately 200 and 600% of the basal level, respectively. Pepsin output was marginally affected by histamine but increased to approximately 3 and 15 times the basal level during treatment with bombesin and eledoisin (3.27 nmol.kg-1.h-1). Somatostatin (SS-14, 15 nmol.kg-1.h-1) inhibited basal acid secretion by 85%. It also inhibited the acid secretion during stimulation with bombesin (68%) and histamine (57%), but although the former effect could be explained by removal of the basal component, the latter could not. Basal pepsin secretion was not affected by SS-14. A slight inhibition (28%) of the peak pepsin response to eledoisin was demonstrated, and bombesin failed to stimulate pepsin secretion during treatment with SS-14. These results indicate that endogenous somatostatin, if present in the cod stomach, could play a role in the regulation of gastric secretion.