In order to assess the interrelationships between stomach and pancreas regarding the secretions of somatostatin-like immunoreactivity (SLI), glucagon (IRG), and insulin (IRI), concentrations of the three hormones were assayed in portal plasma and portal blood flow was measured in enterectomized rats before and after the selective removal of stomach or pancreas.
Portal plasma SLI, IRG, and IRI concentrations were significantly increased by i.v. arginine in control rats (pancreas + stomach present). After gastrectomy, SLI, IRG, and IRI concentrations were, respectively, 52 ± 13% (N = 15; P < 0.005), 234 ± 40% (P < 0.001), and 119 ± 15% (NS) of the pregastrectomy values. A decreased SLI secretion, an increased IRG release, and an unmodified basal IRI release were estimated by portal flow measurement. The A- and B-cell responses to arginine in the gastrectomized rats were significantly higher than in the control rats, while the D-cell response was no longer detectable. After pancreatec-tomy, by contrast, SLI concentrations were 360 ± 75% of the prepancreatectomy values (N = 12; P < 0.001). This reflected an actual increment of SLI release, taking into account the concomitant measurement of portal blood flow. The concentrations of IRG declined by 51 ± 5% (P < 0.001) and IRI was no longer measurable. A-and B-cell responses to arginine also were no longer detectable.
These results suggest that in these experimental conditions (1) the stomach restrained pancreatic A-and B-cell responses to arginine, perhaps through the SLI released from the stomach and (2) the pancreas restrained gastric SLI secretion, perhaps through insulin.