| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, Nevada 89557
The role of the
longitudinal muscle (LM) layer during the peristaltic reflex in the
small and large intestine is unclear. In this study, we have made
double and quadruple simultaneous intracellular recordings from LM and
circular muscle (CM) cells of guinea pig distal colon to correlate the
electrical activities in the two different muscle layers during
circumferential stretch. Simultaneous recordings from LM and CM cells
(<200 µm apart) at the oral region of the colon showed that
excitatory junction potentials (EJPs) discharged synchronously in both
muscle layers for periods of up to 6 h. Similarly, at the anal
region of the colon, inhibitory junction potentials (IJPs) discharged
synchronously in the two muscle layers. Quadruple recordings from LM
and CM orally at the same time as from the LM and CM anally revealed
that IJPs occurred synchronously in the LM and CM anally at the same
time as EJPs in LM and CM located 20 mm orally. Oral EJPs and anal IJPs
were linearly related in amplitude between the two muscle layers.
Spatiotemporal maps generated from simultaneous video imaging of the
movements of the colon, combined with intracellular recordings,
revealed that some LM contractions orally could be correlated in time
with IJPs in CM cells anally.
N
-nitro-L-arginine
(L-NA; 100 µM) abolished the IJP in LM, whereas a
prominent L-NA-resistant "fast" IJP was always observed
in CM. In summary, in stretched preparations, synchronized EJPs in both LM and CM orally are generated by synchronized firing of many ascending
interneurons, which simultaneously activate excitatory motor neurons to
both muscle layers. Similarly, synchronized IJPs in both LM and CM
anally are generated by synchronized firing of many descending
interneurons, which simultaneously activate inhibitory motor neurons to
both muscle layers. This synchronized motor activity ensures that both
muscles around the entire circumference are excited orally at the same
time as inhibited anally, thus producing net aboral propulsion.
circular muscle; inhibitory junction potential; excitatory junction potential; myenteric neuron; peristaltic reflex; peristalsis
This article has been cited by other articles:
|
|
 |
|
  J. D. Chambers, J. C. Bornstein, and E. A. Thomas Insights into mechanisms of intestinal segmentation in guinea pigs: a combined computational modeling and in vitro study Am J Physiol Gastrointest Liver Physiol, September 1, 2008; 295(3): G534 - G541. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 E. J. Dickson, G. W. Hennig, D. J. Heredia, H.-T. Lee, P. O. Bayguinov, N. J. Spencer, and T. K. Smith Polarized intrinsic neural reflexes in response to colonic elongation J. Physiol., September 1, 2008; 586(17): 4225 - 4240. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
H. Korsapati, A. Babaei, V. Bhargava, and R. K. Mittal Cholinergic stimulation induces asynchrony between the circular and longitudinal muscle contraction during esophageal peristalsis Am J Physiol Gastrointest Liver Physiol, March 1, 2008; 294(3): G694 - G698. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
N. J. Spencer, P. Bayguinov, G. W. Hennig, K. J. Park, H.-T. Lee, K. M. Sanders, and T. K. Smith Activation of neural circuitry and Ca2+ waves in longitudinal and circular muscle during CMMCs and the consequences of rectal aganglionosis in mice Am J Physiol Gastrointest Liver Physiol, February 1, 2007; 292(2): G546 - G555. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
R. K. Mittal, B. Padda, V. Bhalla, V. Bhargava, and J. Liu Synchrony between circular and longitudinal muscle contractions during peristalsis in normal subjects Am J Physiol Gastrointest Liver Physiol, March 1, 2006; 290(3): G431 - G438. [Abstract] [Full Text] [PDF]
|
|
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
| Visit Other APS Journals Online |
