Vol. 282, Issue 3, G443-G449, March 2002
The proximal colonic motor response to rectal mechanical and
chemical stimulation
P. A.
Bampton1,
P. G.
Dinning1,
M. L.
Kennedy2,
D. Z.
Lubowski2, and
I. J.
Cook1
Departments of 1 Gastroenterology and 2 Colorectal
Surgery, The St. George Hospital, University of New South Wales,
Sydney, Australia 2217
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.
chenodeoxycholic acid; colon; manometry; peristalsis; afferent