The proximal colonic motor response to rectal mechanical and chemical stimulation.
We aimed to determine whether rectal distension and/or infusion of bile acids stimulates propagating or nonpropagating activity in the unprepared proximal colon in 10 healthy volunteers using a nasocolonic manometric catheter (16 recording sites at 7.5-cm spacing). Sensory thresholds and proximal colonic motor responses were assessed following rectal distension by balloon inflation and rectal instillation of chenodeoxycholic acid. Maximum tolerated balloon volume and the volume that stimulated a desire to defecate were both significantly (P < 0.01) reduced after rectal chenodeoxycholic acid. The frequency of colonic propagating pressure wave sequences decreased significantly in response to initial balloon inflations (P < 0.05), but the frequency doubled after subsequent chenodeoxycholic acid infusion (P < 0.002). Nonpropagating activity decreased after balloon inflation, was not influenced by acid infusion, and demonstrated a further decrease in response to repeat balloon inflation. We concluded that rectal chenodeoxycholic acid in physiological concentrations is a potent stimulus for propagating pressure waves arising in the proximal colon and reduces rectal sensory thresholds. Rectal distension inhibits all colonic motor activity.
Bampton
P A
PA
Department of Gastroenterology, The St. George Hospital, University of New South Wales, Sydney, Australia 2217.
Dinning
P G
PG
Kennedy
M L
ML
Lubowski
D Z
DZ
Cook
I J
IJ
D000328:Adult; D001696:Biomechanical Phenomena; D002404:Catheterization; D002635:Chenodeoxycholic Acid / Q000494:pharmacology*; D003106:Colon / Q000502:physiology*; D005260:Female; D005765:Gastrointestinal Agents / Q000494:pharmacology*; D005769:Gastrointestinal Motility / Q000187:drug effects / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010812:Physical Stimulation; D011312:Pressure; D012007:Rectum / Q000502:physiology*; D012684:Sensory Thresholds
D005765:Gastrointestinal Agents; D002635:Chenodeoxycholic Acid