Regional effects of cholecystokinin octapeptide on colonic phasic and tonic motility in healthy humans

The aim of this study was to assess in nine healthy subjects the effects of CCK octapeptide (CCK-8) on colonic tonic activity, measured by a barostat, and phasic activity, measured by manometry. On 2 consecutive days, recordi ngs were performed in the unprepared proximal and distal colons during intr avenous infusion of saline and CCK-8 at 5, 20, and 40 ng.kg(-1).h(-1). In t he proximal colon CCK-8 induced, at the 20 and 40 ng.kg(-1).h(-1) doses, a tonic relaxation with an increase in barostat bag volume to 156 +/- 25 and 157 +/- 19% of basal (P < 0.01) and a decrease in phasic activity to 72 +/- 7 and 76 +/- 7% of basal (P < 0.01). In the distal colon, CCK-8 induced, a t the 20 and 40 ng.kg(-1).h(-1) doses, a tonic relaxation (increase in intr abag volume to 133 +/- 12 and 149 +/- 15%, respectively; P < 0.01), whereas phasic activity increased (128 +/- 8 and 132 +/- 6%, respectively; P < 0.0 1). Effects of CCK-8 on tonic and phasic activities are different according to the colonic segment. Because meals induce colonic tonic contraction, ou r results suggest that CCK, as a hormone, is not an important mediator of t he response of the colon to feeding in humans.