Sulfate Incorporation into Macromolecules Produced by Cultured Oviductal Epithelium

Oviductal secretions contribute to the environment in which sperm capacitation, fertilization, and early embryo development occur. This laboratory and others have demonstrated that major macromolecular secretions of the oviduct are sulfated. Oviductal epithelial cell cultures in the presence of [35S]-sulfate were used to evaluate the uptake and utilization of sulfate by the oviductal cells. After incubation for various times, cell suspensions containing 35SO4 were filtered on cellulose acetate filters or were TCA-treated and filtered on glass fiber filters. More than 90% of the cells excluded trypan blue. 35S was rapidly taken up into the cells and reached saturation at approximately 1 h at 115.5 ± 22 pM which was maintained throughout the 6 h incubation. Incubation with a specific anion transport inhibitor, SITS, resulted in decreasing sulfate incorporation into the cells. When TCA was used to precipitate the macromolecules, it was found that at 0.5, 1, 2, 4, and 6 h there were 35.8, 55.4, 64.4, 50.0, and 59.9 pM incorporated into TCA precipitable material, respectively. After incorporation of [35S]-sulfate, electrophoresis of cell homogenization indicated at least two sulfated components. The culture system therefore allows the secretory characteristics of the epithelial cells to be observed and controlled more effectively than in intact animals.