Fig. 2. Effects of treatment with 0.1 mmol l^–1 IBMX + 0.5 mmol l^–1 db-cAMP + 1 µmol l^–1 ionomycin on tissue conductance (G_t), unidirectional Cl^– fluxes (J_Cl) and short-circuit current (I_sc). (A) Treatment (at time zero) significantly increased tissue G_t and I_sc. The effect was reversed by mucosal application of the anion channel blocker diphenylamine-2-carboxylate (DPC; 1 mmol l^–1). (B) Drug treatment significantly increased both unidirectional Cl^– fluxes and reversed ion uptake to net Cl^– secretion (P<0.005, paired t-test compared with control period, N=7). J_sm, serosal-to-mucosal Cl^– flux; J_ms, mucosal-to-serosal Cl^– flux. Apical DPC significantly decreased serosal-to-mucosal unidirectional flux (P<0.02, paired t-test compared with previous period, N=7) and restored Cl^– uptake to control levels. (C) Similar post treatment (i.e. after db-cAMP + IBMX + ionomycin) with 100 µmol l^–1 DIDS was without effect on the stimulated I_sc and G_t. Subscripts ser and muc indicate application of drug to the serosal and mucosal sides, respectively. Values are means ± S.E.M.