Gastric inhibitory polypeptide (GIP)

Radioimmunoassayable gastric inhibitory polypeptide was measured in extracts of canine antrum, duodenum, jejunum, and ileum. The highest GIP concentrations were found in the duodenum (347±53 ng/g) and jejunum (300±68 ng/g). An immunochemical similarity was demonstrable between porcine GIP and canine GIP. Dogs prepared with Mann-Bollman fistulae were given an amino acid (AA) mixture or medium-chain triglycerides (MTC) by intraduodenal perfusion. With AA, a peak mean serum concentration of 672±106 pg/ml was reached 15 min after starting the perfusion. MCT resulted in a peak mean serum GIP concentration of 504±55 pg/ml 30 min after beginning the perfusion. When compared to results previously reported from this laboratory, AA and MCT are not as potent as corn oil (long-chain triglyceride) or glucose in stimulating GIP release. We conclude: (1) Immunoassayable GIP concentrations are highest in the canine proximal small intestine. (2) AA and MCT are weak stimulants of GIP release in the dog.This study was supported in part by the Bremer Foundation, 521532-7308, the National Institute of Arthritis and Metabolic Disease 5T01-AM05118-19, and General Clinical Research Center Program, National Institutes of Health RR-34, and National Cancer Institute 5F22-CA00776-02.