Cholecystokinin does not stimulate prosomatostatin-derived peptides in man.
In man, plasma cholecystokinin (CCK) and somatostatin-28 (S-28) levels increase after ingestion of a mixed meal. Both peptides originate from the gastrointestinal tract. In supra- and periphysiological doses, CCK stimulates the release of somatostatin-14 from in vitro pancreatic islets and gastric cells and increases circulating somatostatin-like immunoreactivity in dogs, leading to the conjecture that CCK regulates somatostatin-like immunoreactivity secretion. Nonetheless, whether CCK is responsible in part for the meal-induced rise in S-28 in man has not been established. Therefore, the present study was designed to determine if CCK, at both physiological and supraphysiological concentrations, increases the circulating levels of prosomatostatin (proS)-derived peptides in humans. On 3 separate days, five healthy men ate a mixed liquid meal or received iv infusions of CCK at rates of 18 or 38 pmol/kg.h. Plasma levels of pro-S-derived peptides, including pro-S, S-14, S-13, S-28, and CCK, were measured. Basal CCK levels averaged 0.9 +/- 0.1 pmol/L and increased after the meal to a peak level of 5.4 +/- 1.5 pmol/L and averaged 3.1 +/- 1.2 pmol/L over 90 min. The mean basal levels of pro-S, S-14, and S-13, measured collectively, was 6.1 +/- 0.4 pmol/L eq S14 and was unaltered by food intake. The S-28 level was 6.7 +/- 0.6 pmol/L and rose to a zenith of 13.1 +/- 3.3 pmol/L by 90 min. Infusion of CCK at 18 and 38 pmol/kg.h produced steady state plasma CCK levels of 4.1 +/- 1.1 and 9.9 +/- 1.5 pmol/L, respectively. Basal levels of pro-S-derived peptides were unaltered during the infusion of either the low or high dose of CCK. We conclude that CCK by itself is not a physiological signal to the release of pro-S-derived peptides in man.
Liddle
R A
RA
Department of Medicine, Mount Zion Hospital, San Francisco, California.
Ensinck
J W
JW
D000328:Adult; D002766:Cholecystokinin / Q000097:blood / Q000502:physiology; D004064:Digestive System / Q000187:drug effects; D004068:Digestive System Physiological Phenomena; D004305:Dose-Response Relationship, Drug; D004435:Eating; D006801:Humans; D007262:Infusions, Intravenous; D008297:Male; D010455:Peptides / Q000097:blood*; D011498:Protein Precursors / Q000097:blood*; D012844:Sincalide / Q000008:administration & dosage / Q000097:blood / Q000502:physiology; D013004:Somatostatin / Q000097:blood*; D053561:Somatostatin-28
D010455:Peptides; D011498:Protein Precursors; D013004:Somatostatin; C028456:prosomatostatin; D053561:Somatostatin-28; D002766:Cholecystokinin; D012844:Sincalide