Ca²⁺-activeted Cl⁻ channels were present in mouse VSNs. (A) Ca²⁺-activated Cl⁻ channels were recorded from inside-out patches taken from the dendritic tips. Channel activity was recorded in a symmetric solution that contained (in mM): 140 choline-Cl, 10 HEPES, and 1 EGTA, pH 7.4, and 285 mmol/kg (glucose). At +80 mV, little channel activity was observed with low intracellular Ca²⁺ concentration (150 nM; top trace), but channel activity greatly increased with 1 mM of intracellular Ca²⁺ added to the bath (bottom trace). C, close state. (B) The average current induced by intracellular calcium at V_hold = +80 mV. **, P < 0.01, paired t test; n = 4. (C) RT-PCR experiments detected message from Best2 (241 bp), Best3 (280 bp), Ano1 (226 bp), and Ano2 (607 bp) in mouse VNO. +, experimental groups; −, control groups without RT.