Effects of intestinal secretagogues and distension on small bowel myoelectric activity in fasted and fed conscious dogs

Abstract

SUMMARY1. Defined jejunal segments were perfused with solutions of bile salts and of ricinoleic acid during fasting and after feeding in two groups of conscious dogs, one with the segment in continuity, and the other with a Thiry-Vella loop. Myoelectric activity was recorded from chronically implanted electrodes on the jejunal segment and also from the proximal and distal in situ bowel.2. The results in both groups were identical. During fasting, migrating complexes were present in the segment, but were replaced by intermittent spike activity during chenodeoxycholate without and with ricinoleic acid perfusion. After food, when migrating complexes were replaced by intermittent spike activity, none of the solutions produced any consistent effect.3. In fasted animals, low levels of distension (15 mmHg) interrupted the migrating complexes in the segment and induced intermittent spike activity which was similar to that seen with the secretagogues. The migrating complexes in the main bowel continued during distension. In fed animals, spike activity increased in the segment during distension at 25 mmHg and decreased in the main bowel. In both groups, distension of the segment to pressures between 37-5 and 50 mmHg abolished spike activity both in the distended segment and the main bowel in fasted and fed states, and, in fasted dogs, migrating complexes were also abolished.4. These results demonstrate that the inhibitory intestino-intestinal reflex is mediated through extrinsic nerves and does not require an intact myenteric plexus, whereas the altered myoelectric activity induced by secretagogues is a local effect and does not spread to adjacent bowel through either intrinsic or extrinsic neural pathways. It seems likely that the local motor effect of secretagogues is a result of net secretion, producing distension to pressures below the threshold required to activate the intestino-intestinal reflex.t Present address:

Chenodeoxycholic and Ursodeoxycholic Acids Alter Motility and Fluid Transit in the Canine Ileum

“…Relax ation of small bowel muscle was reported after exposure to bile acids [24] and Haney et al [25] showed that dilute bile and semipure bile acids (tauro-and glycocholate) reduced the transit time of pellets through canine loops. Furthermore, CDCA was demon strated [26] to abolish MMCs in human duo denum and to interrupt MMCs in the canine jejunum [27], As expected [3,28], highly con centrated CDCA (15 mM) reduced water ab sorption by the ileum. Lower concentrated CDCA (5 mM) did not have such a pro nounced effect on water absorption.…”

The effects of motilin on periodic myoelectric spike activity in intact and transected canine small intestine.

“…In two dogs which served as controls, the continuity of the small intestine was not disturbed. In three dogs, a 30 cm jejunal T-V loop was constructed by transaction of the intestine 40 cm distal to the ligament of Treitz (Da Cunha Melo, Summers, Thompson, Wingate & Yanda, 1981).…”

Amelioration of intestinal dysmotility and stasis by octreotide early after small-bowel autotransplantation in dogs

“…16 Since the extrinsic nerve has been shown to modulate initiation or propagation, or both, of phase 3 contractions in the small bowel, 25 denervation may have influenced the pattern of phase-3-like contractions in the intestinal grafts.…”