Single‐channel recordings of chloride currents in primary cultured Drosophila neurons

Single‐chloride‐channel currents were recorded from primary cultured Drosophila neurons by means of the gigaohm‐seal patch‐clamp technique. Small inward‐going current channels were observed in excised inside‐out patches with the external face of the membrane exposed to bathing solutions devoid of K⁺, Na⁺, and Ca²⁺. The inward current was affected by changing the anions but not the cations bathing the cytoplasmic face of the patch. Complete replacement of CI⁻ by glutamate eliminated the current. The current was maintained with intracellular solutions containing NO₃⁻ in place of CI⁻. The single‐channel conductance was estimated to be 7 ps with CI⁻, and 11 ps with NO₃⁻ at 10°C. Possible functions of this anion‐selective channel have been discussed.