Osmolar changes regulate the paracellular permeability of cultured human cervical epithelium
Gorodeski, G.I.; De Santis, B.J.; Goldfarb, J.; Utian, W.H.; Hopfer, U.
American Journal of Physiology 269(4 Pt 1): C870-C877
1995
ISSN/ISBN: 0002-9513 PMID: 7485455 Document Number: 454363
Extracellular nucleotides induce a biphasic change in the transepithelial electrical conductance (GT) of human cervical cells grown on filters: a rapid increase (phase I) followed by a sustained decrease (phase II). To probe the involvement of the intercellular space, its magnitude was varied by manipulating cell volume through changes in extracellular osmolarity. Under baseline conditions (G-T = 115 mS/cm-2 ( apprx 9 OMEGA cntdot cm-2)) and during phase II, hypertonic challenges resulted in an increase in G-T (0.98%-mosmol-1 cntdot l-1 and 0.73% cntdot mosmol-1 cntdot l-1, respectively). However, a hypertonic challenge during phase I decreased G-T (-0.16% cntdot mosmol-1 cntdot l-1). Hypotonic challenges decreased G-T during baseline, phase I, and phase II conditions by -1% cntdot mosmol-1 cntdot l-1. Similar trends were observed with regard to pyranine permeability. Reduction of extracellular calcium increased G-T, abrogated the phase II effect of extracellular ATP, and reversed the effect of a hypertonic challenge. The additive nature of the permeability changes in response to osmotic challenges and to ATP during phase II suggests that different sites are involved in each response, i.e., the resistance of the intercellular space changes with osmolarity and that of the tight junction during phase II.