Biological activity of canine intestinal cholecystokinin-58.

The biological activity of a recently characterized cholecystokinin molecule, canine CCK-58, has been tested using perifused canine gallbladder strips and isolated mouse pancreatic acini. It has been shown that canine CCK-58, purified by affinity chromatography and molecular sieve chromatography, is biologically as potent as canine CCK-39,33 (component II) and synthetic CCK-8. The biological responses were inhibited by dibutyryl cGMP, a known CCK antagonist. CCK-58 is one of the main large molecular forms of CCK in the intestine mucosa. Whether CCK-58 is only an intracellular precursor of other CCK molecules or an important circulating hormone cannot be determined from the data currently available.