ATP DECREASES ACUTELY AND REVERSIBLY TRANSPORT THROUGH THE PARACELLULAR PATHWAY IN HUMAN CERVICAL CELLS

We studied the effect of ATP on transepithelial transport through the paracellular pathway in human cervical cells. Transepithelial conducta nce and transepithelial permeability (determined from the measurements of unidirectional flux of inert molecules) were measured in Caski cel ls grown on permeable support. Transepithelial conductance was 55.9 +/ - 17.7 mS/cm(2) and permeability was 12.5 +/- 2.7 x 10(-6) cm/s for a 0.51-kDa probe. Addition of ATP to the medium decreased acutely and re versibly the conductance and the permeability to probes between 0.18 a nd 10 kDa by 23-31% in a dose-related fashion; the 50% effective conce ntration was 1 mu M, with a maximal effect at 5-10 mu M extracellular ATP. The ATP effect was observed regardless of the pressure gradient a cross the epithelium. These results indicate that extracellular ATP in micromolar concentrations decreases acutely and reversibly the permea bility through the paracellular pathway in cervical cells, possibly by affecting the permeability of the tight junctions and the resistance of the intercellular space. On the basis of these data, we speculate t hat ATP may play a role in the regulation of solutes and fluid transpo rt across the cervical epithelium in vivo.