Experimental conditions affecting in vitro intestinal incorporation of palmitic acid: a methodological approach.

In the rat, a large number of in vitro studies on intestinal fatty acid uptake have been carried out. However, the results obtained under different experimental conditions are often contradictory. The present work is a critical approach to the experimental aspects which may modify in vitro intestinal uptake of fatty acids. Different kinds of intestinal tissue samples (intact, everted or opened rings) were used. The histological changes and the uptake of palmitic acid were measured for each type of sample under different stirring rates, at different incubation times and with micellar solutions of varying composition. It is concluded that 1) opened rings have the highest absorptive capacity with the lowest dispersion; 2) incubation periods longer than 30 minutes do not result in additional palmitic acid uptake and may lead to severe tissue hypoxia as indicated by extensive vacuolization; 3) stirring rates over 1 cycle/sec do not result in increased PA uptake and cause extensive mucosal disruption, particularly in jejunal samples.