AJP - Gastrointestinal and Liver Physiology, Vol 244, Issue 3 291-G294, Copyright © 1983 by American Physiological Society
Migrating action-potential complexes in vitro in cholera-exposed rabbit ileum
K. L. Koch, J. L. Martin and J. R. Mathias
The objective of this study was to determine whether cholera-exposed rabbit
ileum exhibits altered myoelectric activity in vitro, without central
nervous system connections. Whole-cell lysate of Vibrio cholerae, 100 mg in
1 ml saline, was injected into the jejunum of New Zealand White rabbits.
Segments of ileum were removed at 12 and 24 h after inoculation and studied
in vitro using myoelectric recording techniques. Propagating ring
contractions were visualized and corresponded to intense action-potential
activity that propagated over consecutive electrode sites. This altered
myoelectric activity was similar to the previously described migrating
action-potential complex (MAPC) in vivo after infection of rabbit ileum
with live V. cholerae, its wholecell lysate, or the purified enterotoxin
choleragen, with one exception. All MAPC activity propagated aborally in
the in vivo-infected loops; in contrast 26% of the MAPCs propagated
retrograde in the in vitro loops. Control segments were injected with
saline, and no in vitro MAPCs were observed. Thus, the MAPC stimulated by
cholera toxin may be maintained by the enteric nervous system of the gut
wall. Although a role for extrinsic nerves is not excluded, our
observations suggest that the small intestine may work autonomously,
independent of the central nervous system.
