Somatostatin and gastrin release into the gastric lumen in rats

Abstract

Somatostatin and gastrin release into the gastric lumen was investigated in anaesthetized, vagally intact rats. The stomach was perfused at a flow rate of 0.5 mL∙min−1. During perfusion with 0.1 M HCl or buffers of varying pH the somatostatin and gastrin concentrations in the perfusate were <10 pg∙mL−1 and approximately 30 pg∙mL−1, respectively. Peptone caused a slight pH-independent increase in somatostatin release; gastrin release was unchanged despite an increase in serum gastrin from a basal of 15 ± 4 to 155 ± 34 pg∙mL−1 during peptone stimulation. Intravenous infusion of carbachol (1 μg∙kg−1∙min−1) strongly stimulated luminal somatostatin and gastrin release (from 5 ± 1 to 192 ± 52 pg∙mL−1 and from 27 ± 5 to 198 ± 41 pg∙mL−1, respectively) during perfusion with 0.1 M HCl. Phosphate buffer perfusion at pH 7.5 abolished the cholinergic-mediated somatostatin release but the gastrin response was unaffected. It is suggested that changes of luminal hormone concentrations in the rat stomach do not reflect the secretory activity of the endocrine cells in the gastric mucosa.