Asymmetrical XXXX availability from serosal and luminal sides of @entity35 distal colon epithelium.

@entity26 @entity5932 @entity841 @entity519 @entity35
Short-circuit current (Isc) and transepithelial @entity841 ( @entity841 ) of the @entity35 distal colon mucosa are sensitive to acute @entity519 in vitro. The relative contribution of luminal and serosal oxygenation in sustaining Isc and @entity841 was assessed. @entity35 distal colon Isc and @entity841 responses to @entity519 and reoxygenation of preparations of @entity5932 (with and without the mucus gel layer), mounted in an Ussing chamber, and of sacs of everted and non-everted isolated mucosa, were measured. In Ussing chambers, a 5-min total (bilateral) @entity519 reduces Isc and @entity841 by 50 to 70%, while an overshoot was observed on reoxygenation. @entity519 caused about the same effect as total @entity519 , with complete recovery on reoxygenation. Luminal @entity519 had no effect in either Isc or @entity841 . After total @entity519 , selective serosal reoxygenation allowed complete recovery of Isc and @entity841 ; addition of luminal reoxygenation did not further increase Isc and @entity841 . Luminal reoxygenation after total @entity519 did not modify the decrease in Isc and @entity841 , but addition of serosal reoxygenation led to complete recovery. A similar behaviour was seen in isolated mucosa preparations without the mucus gel layer. Baseline Isc and @entity841 of everted sacs were about 45% of those of non-everted sacs, but their response to a @entity519 challenge was slightly attenuated. On reoxygenation, both everted and non-everted sacs showed complete recovery. Summing up: serosal oxygenation is both necessary and sufficient to sustain @entity35 distal colon Isc and @entity841 , while luminal oxygenation is not; there seems to exist a barrier, different from the mucus gel layer, for @entity26 access from the luminal side of the epithelium; and distal colon isolated mucosa everted sac preparations are suboptimally oxygenated.
