Characterization of paracellular permeability in cultured human cervical epithelium: regulation by extracellular adenosine triphosphate.

OBJECTIVE

The purpose of the present study was to compare the permeability and regulation of paracellular transport in human cervical cells with those in epithelial cells of other organs.

METHODS

Cervical cells (ECE16-1, Caski, and HT3) were grown on filters, and transepithelial electrical conductance (GT) and the permeability to pyranine (PPyr) were determined.

RESULTS

Cervical cultures were characterized by high GT (83-125 mS.cm-2) and high PPyr (6.2-18 x 10(-6).sec-1). The GT was not significantly affected by cell density but was increased by 20% by lowering extracellular calcium to 0.45 mmol/L or less. The high values of GT and PPyr and the regulation by extracellular calcium indicate that all three cervical cell lines have "leaky" tight junctional complexes. Addition of extracellular adenosine triphosphate (ATP) at 50 mumol/L to the cervical cultures evoked a biphasic change in GT that was unique to the cervical cells: an initial increase, followed by a sustained decrease by 30% from baseline GT. The decrease of GT was associated with a decrease in PPyr by 17%, indicating that ATP had an effect on the tight junctional/paracellular permeability. The ATP effect was reversible either by washing or by chemical hydrolysis with ATPase. The non-cervical cell lines all responded to extracellular ATP with a transient increase in GT, but not with the pronounced decrease.

CONCLUSION

The permeability of the paracellular pathway can be regulated in cervical epithelia by mechanisms that may be different from those in epithelial cells from other organs.