A VOLUME-SENSITIVE CL- CONDUCTANCE IN A MOUSE NEUROBLASTOMA X RAT DORSAL-ROOT GANGLION-CELL LINE (F11)

Whole cell currents were recorded in F11 cells, a mouse neuroblastoma (NG18TG2) x 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 bat h solution, all cells showed a transient rise in input conductance whi ch 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, ce ll 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 out wardly rectifying current/voltage relationship. Ion substitution exper iments showed that the whole-cell currents were carried by chloride io ns and that the anion selectivity sequence of the conductance was I > Br > Cl > F > acetate. The stilbene derivative 4,4'-diisothiocyanostil bene-2,2'-disulphonic acid (DIDS) caused a reversible, 51% inhibition of the chloride currents. In cells which had already undergone this tr ansient rise in conductance. whole-cell currents with identical proper ties could be activated by changing to a very hypotonic bath solution. Coincident with current activation, this manoeuvre caused a visible s welling of the cell. The increase in conductance and the cell swelling were both reversed by returning to the normal bath solution. In contr ast, when a very hypotonic pipette solution was used, little or no inc rease in cell conductance was observed. These data suggest that the F1 1 cell line possesses a volume-activated chloride conductance which ca n be controlled by manipulating the relative osmolarity of the bath an d pipette solutions.