AJP - Gastrointestinal and Liver Physiology, Vol 247, Issue 1 79-G87, Copyright © 1984 by American Physiological Society
Gastric surface cell function: potential difference and mucosal barrier
J. M. McGreevy
Rabbit fundic mucosa mounted in Ussing chambers for 4 h developed
morphological deterioration of the gastric glands (GG), while the surface
epithelial cell layer (SEC) remained intact. Since the tissues maintained a
steady-state potential difference (PD) and resistance (R), it seemed that
the surface cells might be responsible for both the PD and the R. To test
this hypothesis, segments of fundic mucosa were exposed to selective anoxia
by bubbling the mucosal (anoxic SEC) or serosal (anoxic GG) nutrient
solutions with N2 instead of O2. Control tissues received O2 into both
nutrient solutions. SEC anoxia resulted in a PD and short-circuit current
(Isc) of zero within 10 min; R fell by 60% within 2 h. GG anoxia caused no
change in PD or R over 2 h. Unidirectional fluxes (J) of 36Cl did not
diminish as expected in tissues with no PD or Isc. This persistent JCl in
tissues with a PD of zero was investigated in tissues with anoxic SEC.
Simultaneous unidirectional fluxes of 36Cl and [3H]mannitol were determined
to identify the transcellular (JClcell) and paracellular (JClleak)
components of JCl during SEC anoxia. Similar flux measurements were made in
control tissues (no anoxia). In control tissues, the calculated JClcell
correlated with Isc (r = 0.72, n = 44). In tissues with anoxic SEC, the
JClcell was 0.05 +/- 0.4 (mean +/- SD, n = 44). This series of experiments
suggests that the PD and mucosal barrier characteristics of rabbit gastric
mucosa in Ussing chambers are functions of a healthy surface cell layer.
