AJP - Gastrointestinal and Liver Physiology, Vol 249, Issue 3 416-G421, Copyright © 1985 by American Physiological Society
Migrating action potential complex: unmasked by 6-hydroxydopamine
J. R. Mathias, M. H. Clench, R. H. Davis, C. A. Sninsky and V. M. Pineiro-Carrero
We have previously described the myoelectric characteristics of a single
moving ring contraction, the migrating action potential complex (MAPC), in
rabbit ileal loops exposed to certain bacteria or their enterotoxins. The
MAPC is thought to act as a defense mechanism of the host, clearing
unwanted substances from the lumen. In the present study,
6-hydroxydopamine, a substance that selectively destroys adrenergic
varicosities containing the neurotransmitter norepinephrine, unmasked the
MAPC from the activity front of the migrating motor complex in an
unanesthetized rat model. The animals developed diarrhea and lost weight.
The study suggests that the MAPC may also be a physiological complex and
under the modulation of the enteric nervous system. The MAPC may not be
seen under normal control conditions because the complex migrates with the
activity front and is under inhibitory control. Destroying the inhibitory
mechanisms unmasked the MAPC from the activity front of the migrating motor
complex and allowed neural transmission of the ring contraction.
