Background: Previous work from our laboratory on the effect, in rats, of chronic ethanol intake on the intestinal absorption of ciprofloxacin analogs suggested an increased polarity of the lipoidal membrane constituents without effects on the aqueous environment. The aim of the present study was to investigate the influence of acute ethanol intake on the absorption of the same series of compounds.
Methods: The effects of in situ ethanol exposure on intestinal absorption were determined in rats fed either a standard liquid diet or a 5% (w/v) ethanol-containing liquid diet. Acute intestinal exposure to 5% (w/v) ethanol was performed in situ in each feeding group. The biophysical absorption model was used to establish correlations between the actual absorption rate constants, and the lipophilicity indexes, for each group of rats.
Results: Acute exposure to ethanol produces an increase only in the absorption of hydrophilic homologs in both control and chronic ethanol fed groups. This suggests the absence of homeoviscous adaptation of the intestinal membrane. The biophysical model used allows us to discriminate between the effects of acute and chronic ethanol treatment on the intestinal membrane.
Conclusions: These results suggest that in contrast to previous reports chronic ethanol treatment increases membrane polarity and acute alcohol intake appears to modify membrane fluidity.