AJP - Gastrointestinal and Liver Physiology, Vol 245, Issue 2 307-G312, Copyright © 1983 by American Physiological Society
Some parameters of descending inhibition during colonic propulsion
R. Mancinelli, L. Marzio, M. Pescatori, A. Bertuzzi, S. Salinari, F. Serrao, C. Vulpio and T. Emanuele
Isolated segments of rabbit distal colon were stimulated by distension of
intraluminal balloons, with the aim of investigating the
electrophysiological pattern of descending inhibition (DI) during the
peristaltic reflex. Incidence, duration, and latency of DI were studied by
varying the parameters of stimulation. A linear correlation was found
between stimulus duration and DI duration for stimuli up to 10 s long. DI
duration increased with the distance of the recording site from the
stimulus up to 3 cm. A more complex relation was found between balloon
volume and DI duration. Propagation velocity decreased with the distance
from the stimulus. The relation between ascending excitation and DI was
also studied: ascending excitation could always be suppressed by DI. DI was
examined after addition of anticholinergics, ganglionic blocking agents,
and tetrodotoxin to the organ bath. The results show that DI parameters are
partially related to the stimulus characteristics and that propagation of
DI is neurally mediated through nonadrenergic inhibitory nerves.
