I_sc responses to basolateral bumetanide in the presence of amiloride and barium.

I_sc was measured in normal Ringer solution. Note that amiloride (10 μM, apical) significantly decreased and barium (5 mM, apical) significantly increased I_sc in late distal colon. However, these treatments did not alter the subsequent I_sc responses to bumetanide (100 μM, basolateral) in either colonic segment. Subsequent addition of forskolin (500 nM, basolateral) caused I_sc stimulation in both segments (see text). * P<0.05 and ** P<0.01 vs. prior treatment by paired t test. N = 10.