Volume sensitive chloride currents in primary cultures of human fetal vas deferens epithelial cells

Using the patch-clamp technique, we have identified a large, outwardly rectifying, Cl^--selective whole-cell current in primary cultures of human vas deferens epithelial cells. Whole-cell currents were time-and voltage-dependent and displayed inactivation following depolarising pulses ≤60 mV. Currents were equally permeable to bromide (P(Br)/P(Cl) = 1.05 ± 0.04), iodide (P₁/P(Cl) = 1.06 ± 0.07) and Cl^-, but significantly less permeable to gluconate (P(Gluc)/P(Cl) = 0.23 ± 0.03). Currents spontaneously increased with time after establishing a whole-cell recording, but could be inhibited by exposure to a hypertonic bath solution which reduced inward currents by 68 ± 4%. Subsequent exposure of the cells to a hypotonic bath solution led to a 418 ± 110% increase in inward current, indicating that these currents are regulated by osmolarity. 4,4'-Diisothiocyanatostilbene-2,2'-disulphonic acid (100 μM) produced a rapid and reversible voltage-dependent block (60 ± 5% and 10 ± 7% inhibition of current, measured at ± 60 mV, respectively). Dideoxyforskolin (50 μM) also reduced the volume-sensitive Cl^- current, but with a much slower time course, by 41 ± 13% and 32 ± 16% (measured at ± 60mV, respectively). Tamoxifen (10 μM) had no effect on the whole-cell Cl^-current. These results suggest that vas deferens epithelial cells possess a volume-sensitive Cl^- conductance which has biophysical and pharmacological properties broadly similar to volume-sensitive Cl^- currents previously described in a variety of cell types.