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 (G(T)) and the permeability to pyranine (P-Pyr) were determined. RESULTS: Cervical cultures were characterized by high G(T) (83-125 mS.cm(-2)) and high P-Pyr (6.2-18.10(-6).sec(-1)). The G(T) 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 G(T) and P-Pyr 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 mu mol/L to the cervical cultures evoked a biphasic change in G(T) that was unique to the cervical cells: an initial increase, followed by a sustained decrease by 30% from baseline G(T). The decrease of G(T) was associated with a decrease in P-Pyr 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 G(T), 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.