Differences in cholecystokinin release and gallbladder contraction betweenemulsified and nonemulsified long-chain triglycerides

Background: Fat is a potent stimulus of cholecystokinin (CCK) release. Apar t from lipolysis, fatty acid chain length, and saturation, emulsification m ay also determine the magnitude of CCK release. Methods: We have studied th e effect of emulsification of soybean oil on CCK and pancreatic polypeptide (PP) release (radioimmunoassay [RLA]) and gallbladder motility (ultrasonog raphy). Six healthy subjects were studied on three separate occasions in ra ndom order during (Ij intraduodenal administration of emulsified long-chain triglycerides (LCT) (6 mmol/h for 120 minutes); (2) equimolar amounts of n onemulsified LCT with addition of emulsifier; and (3) saline with emulsifie r (control). Results: Intraduodenal administration of both nonemulsified LC T and emulsified LCT induced significant (p < .05) increases in plasma CCK and PP levels and reductions in gallbladder volume. However, compared with nonemulsified LCT, emulsified LCT resulted in a readier and significantly s tronger CCK release (212 +/- 62 pmol/L per 120 minutes us 36 +/- 7 pmol/L p er 120 minutes; p < .05); PP release (2034 +/- 461 pmol/L per 120 minutes v s 671 +/- 106 pmol/L per 120 minutes; p < .05); and gallbladder contraction (77% +/- 2% us 41% +/- 7%; p < .05). No significant alterations were obser ved in plasma CCK or PP levels and gallbladder volume during administration of saline with emulsifier. Conclusions: Intraduodenal administration of a low-dose emulsified LCT more potently stimulates CCK and PP release and gal lbladder contraction in comparison to equimolar amounts of nonemulsified LC T. These findings point to an important role for solubilization of LCT in d etermining the magnitude of CCK release from the intestine.