Isolation and characterization of enterocytes along the intestinal tract of the gilthead seabream (Sparus aurata L.).

Epithelial cells were successfully isolated along the intestine of the gilthead seabream using a dissociation method based on intracellular-like solutions. Biochemical and physiological tests revealed highly viable cells from all intestinal segments. Image analysis was used to identify cell types in the epithelial preparations which were highly enriched in enterocytes (>95%) over mucous cells. Several digestive hydrolases were determined in the isolated cells. Maltase (M), sucrase (S), leucine aminopeptidase (LA), 5'nucleotidase (5'N), but not gamma-glutamyl transferase (gamma-GT) or alkaline phosphatase (AP) activities were found to be enriched in the epithelial preparations versus the corresponding intestinal homogenates. Comparison of digestive hydrolases revealed the existence of a clear heterogeneity in their expression pattern in the enterocytes, along the intestine. Na(+)-K(+)-ATPase, Na(+)-ATPase and Cl(-)-ATPase activities were also determined in the membrane fraction of isolated cells. Analyses of enzymatic profiles revealed a clear asymmetry in the distribution of all Mg(2+)-dependent ATPases; that is, maximal Na(+)-K(+)- and Na(+)-ATPase activities were observed in the enterocytes from pyloric caeca, while Cl(-)-ATPase activity was about twice as high in the enterocytes from anterior and posterior intestines compared with pyloric caeca. This is the first report demonstrating the existence of heterogeneous metabolic and enzymatic profiles in different enterocyte populations from euryhaline teleosts.