SLC26A3 and CFTR are involved in the HCO3−-induced hyperpolarization. Measurements of membrane potential using DISC3(5) in noncapacitated mouse spermatozoa. On the left are Representative fluorescent traces with internal calibration using valinomycin (val) and subsequent KCl additions to determine the Em obtained by HCO3− addition. The Em values (calculated with the internal calibration, right side of the trace) before and after the addition of HCO3− are indicated in each trace (arrows) in the presence of DMSO (A), Tdap (B), DOG (C), or inh-172 (D). On the right is a summary of the initial Em (In), the Em reached after the HCO3− addition (HCO3−) in the absence (black bars) or presence of SLC26A3 (Tdap and 5099), SLC26A6 (DOG and PMA) or CFTR (inh-172) inhibitors (gray bars) at the indicated concentrations. Results are means ± SEM. N.S., P > 0.05; *P ≤ 0.05; **P ≤ 0.01; ***P ≤ 0.001 (n = 3).