Effect of ethanol on intestinal uptake of fatty acids, fatty alcohols, and cholesterol

The effect of acute exposure of the rabbit jejunum to ethanol on the uptake of fatty acids, fatty alcohols, and cholesterol was examined using a previously validated in vitro technique. The effective resistance of the intestinal unstirred water layer was determined from the rate of uptake of a homologous series of fatty alcohols. The addition of ethanol to the incubation or preincubation solutions had no effect on the uptake of these probes when the bulk phase was stirred at 600 rpm, but uptake was higher in the ethanol-exposed samples when the bulk phase was unstirred. Increasing the concentration of ethanol in the bulk phase was associated with a progressive decline in the rate of uptake of acetic, lauric, myristic, and palmitic acids, whereas the uptake of hexanoic, octanoic, and decanoic acids was unaffected, and the uptake of cholesterol was increased. Acute exposure of the intestine to ethanol was associated with an increase in the electrical conductance of the tissue, with no associated change noted in the tight junctions on transmission electron microscopy or in the surface epithelium on scanning electron microscopy. The results suggest that acute exposure of the rabbit intestine to ethanol is associated with a selective decline in the passive permeability properties of the membrane towards only certain lipids and that the effective resistance of the unstirred layer is influenced by ethanol only when the bulk phase is unstirred and the resistance is high.