Figure 6

Inhibition of forskolin-stimulated I _sc by bumetanide and DIOA. A) Summary of inhibition by basolateral bumetanide (BUM) (n = 11) of cAMP-stimulated I _sc (forskolin, FSK + IBMX). Epithelia were incubated in dexamethasone and Na⁺ transport was inhibited with apical amiloride before stimulation by cAMP. Note that I _sc does not return after only bumetanide to the basal Cl^- secretion rate in amiloride (dotted line). B) Representative recording of V_T and the response to apical amiloride forskolin + IBMX, basolateral DIOA and basolateral bumetanide (BUM). C) Summary of response of I _sc to DIOA and bumetanide (BUM) (n = 3) after stimulation by forskolin+ IBMX. Na⁺ transport was inhibited with apical amiloride before stimulation. Note that I _sc returns after both DIOA and bumetanide to the basal Cl^- secretion rate in amiloride (dotted line). Summary data (A and C) are mean ± SEM; *, P < 0.05 compared to bar immediately to the left; NSA, not significantly different from amiloride.