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, recordings were performed in the unprepared proximal and distal colons during intravenous infusion of saline and CCK-8 at 5, 20, and 40 ng · kg¹ · h¹. In the proximal colon CCK-8 induced, at the 20 and 40 ng · kg¹ · h¹ 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, at the 20 and 40 ng · kg¹ · h¹ doses, a tonic relaxation (increase in intrabag volume to 133 ± 12 and 149 ± 15%, respectively; P < 0.01), whereas phasic activity increased (128 ± 8 and 132 ± 6%, respectively; P < 0.01). Effects of CCK-8 on tonic and phasic activities are different according to the colonic segment. Because meals induce colonic tonic contraction, our results suggest that CCK, as a hormone, is not an important mediator of the response of the colon to feeding in humans.

colon; colonic motor activity; colonic tone; barostat