Fig. 5. The inhibition of short-circuit current (I_sc) by 10 and 100 µmol l^-1 quinine added to the mucosal Ringer. Note that removal of quinine does not reverse the inhibition of I_sc, while the addition of 10 mmol l^-1 Ba²⁺ does produce a further inhibition that is reversible. In all experiments, NaCl Ringer was the mucosal and serosal bathing solution. The values for the Lorentzian plateau at low frequencies (S_o) decrease with I_sc as the quinine concentration is increased and remain low after quinine wash-out and during Ba²⁺ treatment. S_o does increase when I_sc values return to more negative values following the removal of Ba²⁺. Values marked with an asterisk indicate that I_sc and S_o are reduced significantly relative to the control values. The value marked with a dagger indicates that the value of I_sc following treatment with 10 mmol l^-1 Ba²⁺ is significantly different from the quinine wash-out value. The corner frequencies (f_c) do not change significantly over the course of the mucosal solution changes. Values are means ± S.E.M., N=6.