ELECTROPHYSIOLOGICAL BASIS OF HUMAN FALLOPIAN TUBAL FLUID FORMATION

A preparation for the maintenance of human Fallopian tubal epithelial cells as a polarized layer in primary culture was used to study the el ectrophysiological basis of tubal fluid formation in terms of the move ment of Na+, K+ and Cl- ions. Transepithelial potential difference (PD ) and short-circuit current (I-scc) were recorded by mounting the epit helial cells in a modified Ussing chamber. Resistance (R) was calculat ed from the measurements of PD and I-scc. The epithelia, although conf luent, formed a 'leaky' electrical system and resistances greater than 300 Omega cm(-2) were rarely achieved. The sodium channel blocker, am iloride (100 mu mol l(-1)), produced only small effects on PD and I-sc c. The potassium channel blocker, tetraethylammonium chloride (TEA) (2 5 mmol l(-1)), also produced small, but significant changes in PD, I-s cc and R while the chloride channel blocker, -acetamido-4'-isothiocyan ostilbene-2.2'-disulfonic acid (SITS) (1 mmol l(-1)), induced a marked increase in PD and I-scc, and a fall in R, when added to the basal su rface of the cells. Bathing the apical surface of the cells with chlor ide-free medium also produced a marked increase in PD, I-scc and R; ba thing the basal surface of the cells with chloride-free medium produce d a marked decrease in PD and I-scc. Extracellular ATP (10 mu mol l(-1 )), added to either the apical or the basal surface of the cells, indu ced a transient increase in PD and I-scc and a decrease in R. Amilorid e, TEA or furosemide had no effect on the response of the cells to ATP . SITS, applied to the apical surface, significantly reduced the respo nse of the cells to ATP. We conclude that the major driving force for human tubal fluid formation is the transepithelial secretion of chlori de ions into the oviduct lumen and that exogenous ATP is a potential m odulator of secretion.