Neural mediation of the motilin motor effect on the human
antrum.
Boivin, M., L. Rivero Pinelo, S. St-Pierre, and P. Poitras.
H[circumflex]opital Saint-Luc, Universit[acute]e de Montr[acute]eal
and INRS Sant[acute]e, Universit[acute]e du Qu[acute]ebec
APStracts 3:0188G, 1996.
Background/aims: To elucidate the mode of action of motilin on the
stimulation of human gastrointestinal motility, we studied the effect
of exogenous motilin during muscarinic or serotoninergic
pharmacological blockade. Methods: Manometric recording of the
interdigestive antroduodenal motility was carried out in 27 healthy
volunteers until the appearance of a spontaneous antral phase III.
The tested blocker was then administered IV and was followed 30 min.
later by a 10 min. infusion of synthetic human motilin (50?ng/kg).
Results: Motilin administered on a background of saline induced a
premature phase III migrating from the antrum to the duodenum in
every tested subjects (n=5). A low dose of atropine (5 [mu]g/kg/hr
for 90 min.), inhibited the motilin effect in 2/5 subjects (NS),
while a high dose of atropine (15?[mu]g/kg given in 30 min.) blocked
the motilin induced premature antral phase III in all occasions (n=5;
p<.01). Exogenous motilin given with ondansetron at low dose
(8 mg given in 15 min. followed by 1 mg/hr for 90 min.) or with
ondansetron at high dose (32 mg given in 30 min.), was without effect
in 3/7 (NS) or in 2/5 (NS) subjects respectively. During the
administration of atropine 15?[mu]g/kg, where exogenous motilin
always failed to induce a premature antral phase III motor, a phase
III type activity was generated at the duodenum in 4/5 subjects.
Conclusions: 1) The induction by motilin of phase III activity in
human antrum is dependant upon muscarinic mediation; 2) the
contractile effect of motilin on human duodenum involves a non
cholinergic mechanism, different therefore from the antral pathway.
Received 15 September 1995; accepted in final form 20 September
1996.
APS Manuscript Number G411-5.
Article publication pending Am. J. Physiol. (Gastrointest. Liver
Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 7 October 1996