AJP - Gastrointestinal and Liver Physiology, Vol 248, Issue 5 569-G573, Copyright © 1985 by American Physiological Society
Cholecystokinin potently releases somatostatin from canine fundic mucosal cells in short-term culture
A. H. Soll, D. A. Amirian, J. Park, J. D. Elashoff and T. Yamada
Previous studies indicated that gastrin-17 (G-17) and the octapeptide of
colecystokinin (CCK-8) were equally potent in their interaction with
receptors for 125I-[Leu15]G-17 on isolated canine parietal cells. These
findings were inconsistent with the poor efficacy of CCK-8 compared with
G-17 as stimuli of acid secretion in dogs. The present study examines the
effects of G-17 and CCK-8 on the release of somatostatinlike
immunoreactivity (SLI) from a fraction of small canine fundic mucosal cells
separated by elutriation and placed in short-term culture. CCK-8 was
considerably more potent and more effective than G-17 as a stimulant of SLI
release from these cultured cells. CCK-8 was slightly more potent than G-17
in inhibiting 125I-[Leu15]G-17 binding to receptors in the same elutriator
fraction. Our present findings support the hypothesis that the poor
efficacy of CCK compared with G-17 as a stimulant of acid secretion may
reflect pronounced activation of somatostatin-mediated acid-inhibitory
mechanisms by CCK-8. The present data indicate that differences in affinity
between CCK-8 and G-17 at the 125I[Leu15]G-17 receptor probably do not
account for the greater efficacy of CCK-8; the receptor or cell activation
mechanisms underlying this greater efficacy of CCK-8 on SLI release remain
to be elucidated.
