The present study was designed to examine the effect of hypophysectomy upon gastric and pancreatic D cell function by determining the concentration of somatostatin-like immunoreactivity (SLI) in the venous effluents of the pancreas and stomach in response to an intragastric liver meal and acid load. In five sham-hypophysectomized (sham-hypox) control dogs, mean inferior vena cava SLI levels increased by 100 pg/ml above baseline in response to the liver meal and rose by an additional 450 pg/ml after the intragastric acid load. In the four hypophysectomized (hypox) dogs, mean inferior vena cava SLI levels did not differ significantly from the controls either before or after the liver meal, but decreased below baseline levels in response to the acid load, differing significantly from the values of the sham-hypox dogs. Pancreatic vein SLI levels of the sham-hypox dogs rose significantly by 600 pg/ml in response to the protein meal and increased further by 1000 pg/ml after the acid load. In the hypox group, pancreatic vein SLI did not rise significantly after the protein meal, and a slight decrease was observed after the acid load. In the sham-hypox dogs, antral vein SLI levels rose significantly by 200 pg/ml in response to the protein meal, and a further 16-fold increase followed the acid load. In the hypox group, however, SLI levels did not rise significantly in response to the liver meal, and they decreased significantly below baseline values after the intragastric acid load. In the sham-hypox dogs, fundic vein SLI levels rose significantly by 200 pg/ml after the liver meal and increased by an additional 600 pg/ml in response to the acid. In the hypox dogs, fundic vein SLI levels did not rise significantly above baseline after either the liver meal or the acid load, although no significant differences between the two groups were noted. The disappearance halftime of synthetic somatostatin from the circulation of the hypox dogs was 2.23 min, not different from normal dogs. It is concluded that in hypox dogs the gastric and pancreatic D cell responses to an intragastric liver meal and to an acid load are markedly altered.
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