AJP - Gastrointestinal and Liver Physiology, Vol 261, Issue 1 78-G82, Copyright © 1991 by American Physiological Society
Electrical slow-wave activity from the circular layer of cat terminal antrum
L. M. Renzetti, M. B. Wang and J. P. Ryan
Department of Physiology, Temple University School of Medicine, Philadelphia, Pennsylvania 19140.
Intracellular recording techniques were used to characterize the electrical
slow-wave activity through the thickness of the circular muscle layer of
the cat terminal antrum. Muscle strips were pinned out in cross section to
the floor of a recording chamber perfused with Krebs buffer. Circular
muscle cells from the myenteric to the submucosal border then were impaled
with 20- to 40-M omega glass microelectrodes, and slow-wave activity was
recorded. Slow waves from the myenteric side of the circular layer
consisted of an upstroke depolarization, a prominent plateau phase, and a
downstroke repolarization. Slow-wave characteristics for cells along the
myenteric border were Em, -74.2 +/- 1.3 mV; duration, 5.3 +/- 0.5 s;
upstroke amplitude, 29.4 +/- 3.4 mV; upstroke velocity, 0.20 +/- 0.03 V/s;
and frequency, 5.8 +/- 0.5/min. Slow waves from muscle cells along the
submucosal side of the preparation lacked a discernible plateau phase. Slow
waves from submucosal border cells had the following characteristics: Em,
-80.4 +/- 1.4 mV (P less than 0.01); duration, 3.5 +/- 0.4 s (P less than
0.01); upstroke amplitude, 44.0 +/- 2.4 mV (P less than 0.01); upstroke
velocity, 0.56 +/- 0.06 V/s (P less than 0.01); and frequency, 4.2 +/-
0.4/min (P less than 0.05). Slow waves were not affected by 10(-7)M
tetrodotoxin and 10(-6)M atropine or by removal of the longitudinal muscle
layer. Slow-wave activity within each region was maintained after
dissecting the circular layer into submucosal and myenteric segments. The
results suggest that two distinct slow waves exist within the circular
muscle layer of the cat terminal antrum.(ABSTRACT TRUNCATED AT 250 WORDS)
