Figure 11. Inhibitor effects suggest basal I_eq and HCO₃⁻ secretion depend on CFTR and on Ca²⁺-dependent, membrane-bound adenylyl cyclase activity, but not on HCO₃⁻ -stimulated soluble adenylyl cyclase.

A, basal I_eq was abolished by apical addition of the CFTR open channel blocker GlyH-101 (100 μmol l⁻¹, n= 4). B, basal I_eq and net HCO₃⁻ secretion were inhibited by bilateral addition of 200 μmol l⁻¹ Rp-cAMPS, a competitive inhibitor of cAMP-dependent PKA (n= 4). C, basal I_eq and HCO₃⁻ secretion were reduced by basolateral MDL-12330A (200 μmol l⁻¹), an inhibitor of membrane-bound adenylyl cyclase (n= 4). D, inhibition of basal I_eq and HCO₃⁻ secretion by apical 2-APB (100 μmol l⁻¹), an inhibitor of store-operated Ca²⁺ channels (n= 3). E, an inhibitor of HCO₃⁻-stimulated soluble isoform of adenylyl cyclase, 2-HE (20 μmol l⁻¹), had no effect on I_eq or HCO₃⁻ secretion (n= 3 each) when added bilaterally. F, summary of inhibitor effects on basal anion transport. ▪, I_eq; □, HCO₃⁻ secretion.