Identical patterns of somatostatin secretion from isolated antrum and fundus of rat stomach.

The patterns of somatostatin secretion from the fundus, the main source of somatostatin, and the antrum, the site of paracrine regulation of gastrin secretion, were examined using perifused antral and fundic segments from rat stomach. Gastrin secretion fundic segments from rat stomach. Gastrin secretion could be obtained from antral segments only. Somatostatin secretion was obtained from both antral and fundic segments. 1,1-Dimethyl-4-phenylpiperazinium (DMPP) (10(-5) and 10(-4) M) and bombesin-14 (10(-8) and 10(-6) M) caused concentration-dependent increases in somatostatin secretion that were of the same magnitude in antral and fundic segments. These increases were also of the same magnitude as those obtained in the vascularly perfused whole stomach. Atropine (3 X 10(-7) M) inhibited the somatostatin response to DMPP (10(-4) M) to the same extent in antral (50 +/- 12% inhibition) and fundic (55 +/- 12% inhibition) segments. Hexamethonium (10(-5) M) also inhibited the response to DMPP to the same extent in antral (80 +/- 9%) and fundic (78 +/- 19%) segments. Methacholine caused a typically muscarinic decrease in somatostatin secretion that was of the same magnitude in antral (27 +/- 6%) and fundic (25 +/- 6%) segments. The identical patterns of somatostatin secretion from the two regions of the stomach imply that somatostatin secretion measured in the vascularly perfused whole stomach is a valid reflection of somatostatin secretion by the antrum.