A volume-sensitive Cl − conductance in a mouse neuroblastoma × rat dorsal root ganglion cell line (F11)

Abstract

Whole cell currents were recorded in F11 cells, a mouse neuroblastoma (NG18TG2) × rat DRG hybrid cell line, using pipette and bath solutions intended to isolate any chloride conductance pathways. When recording with a pipette solution which was 40 mmol·kg −1 hypotonic to the bath solution, all cells showed a transient rise in input conductance which peaked 5.3±0.4 min after breaking into the cell and returned to the basal state 11.7±1.2 min later. At the peak of the effect, cell conductance had increased approximately sixfold. The use of short (300 ms) duration voltage steps at the peak of the conductance increase evoked whole-cell currents which were time-independent and had an outwardly rectifying current/voltage relationship. Ion substitution experiments showed that the whole-cell currents were carried by chloride ions and that the anion selectivity sequence of the conductance was I > Br > Cl > F > acetate. The stilbene derivative 4,4′-diisothiocyanostilbene-2,2′-disulphonic acid (DIDS) caused a reversible, 51% inhibition of the chloride currents. In cells which had already undergone this transient rise in conductance, whole-cell currents with identical properties could be activated by changing to a very hypotonic bath solution. Coincident with current activation, this manoeuvre caused a visible swelling of the cell. The increase in conductance and the cell swelling were both reversed by returning to the normal bath solution. In contrast, when a very hypotonic pipette solution was used, little or no increase in cell conductance was observed. These data suggest that the F11 cell line possesses a volume-activated chloride conductance which can be controlled by manipulating the relative osmolarity of the bath and pipette solutions.