Effect of 50 percent distal small bowel bypass on gastric secretory function in rhesus monkeys

Six rhesus monkeys had basal acid output and histamine-stimulated maximal acid output measured before and at 10 weeks and 6 months after 50 percent distal small bowel bypass. At each stage fasting serum gastrin was measured in all animals and fasting serum gastric inhibitory polypeptide in two animas. No change in basal or maximal acid output occurred after a sham operation carried out in two of the animals. The mean preoperative basal acid output (0.17 ± 0.02) increased to 0.49 ± 0.04 at 10 weeks after bypass (p <0.001) and then decreased significantly to 0.33 ± 0.03 mEq/kg/hour at 6 months (p <0.001). Preoperative maximal acid output (0.43 ± 0.06) increased to 0.76 ± 0.10 mEq/kg/hour at 10 weeks (p <0.001) and remained at that level at 6 months. Small bowel biopsy specimens at 6 months showed characteristic changes in both proximal and distal small bowel segments. Fasting gastrin and gastric inhibitory polypeptide levels did not change significantly during the study. A comparison of these results with those obtained after 50 percent distal small bowel resection in a previous study revealed a similar proportional increase in maximal acid output in both early (resection, 78 ± 20 percent; bypass, 77 ± 23 percent) and late postoperative studies (resection. 57 ± 14 percent; bypass, 74 ± 19 percent). However, the early increase in basal acid output after resection (370 ± 50 percent) was sustained and was significantly greater (p <0.005) than the early illsustained increase (188 ± 24 percent) after bypass.