J. Sehested et al., METHODOLOGICAL AND FUNCTIONAL-ASPECTS OF THE ISOLATED BOVINE RUMEN EPITHELIUM IN USSING CHAMBER FLUX STUDIES, Acta agriculturae Scandinavica. Section A, Animal science, 46(2), 1996, pp. 76-86
The properties of isolated sheets of bovine rumen epithelium in the Us
sing chamber system were studied. The viability and time-dependent cha
nge in performance, as expressed by electrical parameters, was accepta
ble and comparable to what has been obtained with other epithelia in v
itro. The viability and time-dependent change in performance was not i
nfluenced by transport time (5 to 45 minutes) between the slaughterhou
se and the laboratory. Flux rates of Na-22(+) and C-14-propionate show
ed that an equilibration period of 45 minutes after addition of tracer
s will be sufficient to obtain steady-state conditions with this epith
elium. Compared with the time-dependent changes in electrical paramete
rs, this shows that rumen epithelium cannot truly be used as its own c
ontrol over time. The varying papillation caused surface enlargement f
actors between one and five, estimated by the dry weight of stripped e
pithelium. However, the dry weight was not correlated to epithelial ca
pacitance or flux rates. It is concluded that the papillae do not cont
ribute significantly to the fluxes measured in vitro. and that correct
ion for surface enlargement is not essential for the evaluation of flu
x data. The pH was 0.27 to 0.30 units lower at the epithelial surface
than in the bulk solution. and the pH difference was not influenced by
glucose or SCFA free solutions, nor by Amiloride (1 mmol l(-1)). The
observed lower epithelial surface pH seems not to be an acidic microcl
imate in the traditional sense, but could be explained by a negatively
charged surface potential of the epithelial cells.