The release of rat intestinal cholecystokinin after oral trypsin inhibitor measured by bio-assay.
The distribution, molecular form and release of cholecystokinin (CCK)-like activity in extracts of rat small intestine was studied with an in vitro gall-bladder bio-assay. In contrast to the reported heterogeneity of CCK-like immunoreactivity in the intestine, only a single molecular form of CCK-like activity was detected using the bio-assay. 2. The CCK-like activity eluted from Sephadex G50 with a Kav of 0.69, after the triacontriapeptide of cholecystokinin (CCK33) and before cholecystokinin octapeptide 2500, may represent the 22 amino acid peptide of CCK (CCK22). The bio-assay peak of CCK-like activity had pancreozymin activity and CCK/gastrin C terminal immunoreactivity. The CCK-like activity weas readily extracted from the small intestine at neutral pH, but subsequent treatment with cold 0.5 M-acetic acid extracted further CCK-like activity of the same molecular form as that recovered under neutral conditions. 3. The bio-assay detected no CCK-like activity, nor was pancreozymin-like activity found in fractions corresponding to CCK33 or CCK8 after Sephadex G50 chromatography of rat intestinal extracts. 4. Oral trypsin inhibitor was a potent stimulus for the release of CCK-like activity from the upper small intestine of the rat. After oral trypsin inhibitor release, CCK-like activity was rapidly resynthesized.
D000818:Animals; D001681:Biological Assay; D002766:Cholecystokinin / Q000378:metabolism*; D002850:Chromatography, Gel; D005704:Gallbladder; D066298:In Vitro Techniques; D007421:Intestine, Small / Q000187:drug effects / Q000378:metabolism*; D008297:Male; D008970:Molecular Weight; D011817:Rabbits; D051381:Rats; D011919:Rats, Inbred Strains; D014361:Trypsin Inhibitors / Q000494:pharmacology*
D014361:Trypsin Inhibitors; D002766:Cholecystokinin