Relationship between intraduodenal 5-hydroxytryptamine release and interdigestive contractions in dogs.
BACKGROUND
5-hydroxytryptamine (5-HT) is released into the intestinal lumen during the fasting state. However, the relationship between the intraduodenal 5-HT and the interdigestive cyclic motor activity in conscious dogs is unclear.


OBJECTIVE
To correlate intraduodenal 5-HT concentrations with the interdigestive gastroduodenal migrating motor complex (MMC).


METHODS
6 dogs were implanted with 2 force transducers for recording gastroduodenal contractions and 2 catheters for measuring duodenal volume by a non-absorbable marker perfusion technique. Intraduodenal 5-HT concentrations were determined by high performance liquid chromatography at 5-min intervals.


RESULTS
During fasting, gastroduodenal motor activity cycled as the MMC; luminal 5-HT concentrations and total outputs varied cyclically in temporal association with the MMC. Mean 5-HT concentrations peaked during phase II (P<0.05 vs. phase I and III), and 5-HT outputs during phases II or III were greater than during phase I (P<0.05). Exogenous motilin (0.3 microg/kg-hr, IV) stimulated 5-HT release into the duodenal lumen with peak values (P<0.05) during motilin-induced phase II and III. Gastroduodenal motor activity was not altered, however, during exogenous intraduodenal administration of 5-HT (300 ng/mL-min).


CONCLUSIONS
5-HT is released cyclically into the duodenal lumen in close temporal association with the MMC, but its physiologic significance in regulation of gastroduodenal motility is unknown.
Tanaka
Toshiyuki
T
Second Department of Surgery, Gunma University Faculty of Medicine, 3-39-15 Shoaw-cho, Maebashi city, Gunma 371-8511, Japan.
Mizumoto
Akiyoshi
A
Mochiki
Erito
E
Haga
Norihiro
N
Suzuki
Hideki
H
Itoh
Zen
Z
D000818:Animals; D004285:Dogs; D004386:Duodenum / Q000378:metabolism*; D005215:Fasting / Q000502:physiology; D005769:Gastrointestinal Motility / Q000187:drug effects / Q000502:physiology*; D009037:Motilin / Q000008:administration & dosage / Q000502:physiology; D009119:Muscle Contraction / Q000502:physiology; D009130:Muscle, Smooth / Q000502:physiology; D016065:Myoelectric Complex, Migrating / Q000502:physiology; D012701:Serotonin / Q000008:administration & dosage / Q000378:metabolism*
D012701:Serotonin; D009037:Motilin