Effects of tannic acid and lanthanum on the membrane potential of isolated caudal epididymal principal cells. (A) Representative DiBAC4(3) fluorescence of single principal cells isolated from cauda epididymis of rats before (CTL, denoting the control condition) and after addition of 100 µM tannic acid (+TA; left) or 100 µM La3+ (+La; right) and the subsequent addition of either inhibitors. Arrows indicate the cells that would have been selected for measurement. (B) Typical tracings showing the fast depolarization triggered by tannic acid or the gradually hyperpolarizing response induced by La3+ on control cells. Subsequent addition of La3+ to TA-treated cells caused hyperpolarization, but pretreatment with La3+ prevented the depolarizing effect of TA. (C) Summary of the end-point effects of TA and La3+ (30-min treatment) on the membrane potential of principal cells from different culture days. *, P < 0.05; **, P < 0.01; ***, P < 0.001; ns, no significant difference (one-way ANOVA).
