Effect of colectomy on cholecystokinin and gastrin release.

Studies were conducted to determine the effect of resection of the colon on the release of cholecystokinin (CCK) and gastrin. A standard food stimulation test was performed in five dogs. Peripheral blood samples were collected for future measurement of CCK and gastrin by specific radioimmunoassay. Each dog underwent subtotal colectomy with side-to-end ileoproctostomy. The food stimulation test was repeated at approximately weekly intervals for eight weeks after colectomy. Basal plasma CCK levels of 139 +/- 21 pg/ml before colectomy did not change after colectomy. Total amount CCK released after food was increased significantly at both four (5.94 +/- 0.78 ng min/ml) and eight (13.00 +/- 2.72 ng min/ml) weeks after colectomy in comparison with that observed prior to colectomy (2.94 +/- 0.54 ng min/ml). Basal serum gastrin levels of 28 +/- 9 pg/ml did not change significantly after colectomy. Total amount of gastrin released after food was increased significantly at both two (8651 +/- 2294 pg min/ml) and three (6940 +/- 1426 pg min/ml) weeks after operation, but at none of the later weeks. The precolectomy output, used for comparison, was 5608 +/- 1346 pg min/ml. It was concluded that resection of the colon leads to an increase in release of CCK and gastrin after food stimulation. This finding provides further evidence that the colon contains a factor that inhibits the release of CCK and gastrin, and that the colon functions as an endocrine organ.