Fig. 10.

H⁺-ATPase inhibition eliminates bumetanide-induced changes in Cl⁻ flux. Mice were fed the NaCl-replete gelled diet described in methods and were given aldosterone by minipump (200 μg·kg body wt⁻¹·day⁻¹) for 5–7 days before euthanasia. The effect of bumetanide (100 μM) on J_Cl was examined during ENaC blockade (3 μM benzamil in the luminal fluid) in the presence (right) and absence (left) of apical H⁺ blockade (bafilomycin, 5 nM, the luminal fluid). As shown, H⁺-ATPase blockade prevented the increase in Cl⁻ absorption observed with bumetanide application. Solid lines display results of experiments in which bumetanide vehicle was applied in the first period and bumetanide (plus vehicle) was applied in the second. Dashed lines indicate experiments where the order was reversed (i.e., bumetanide was applied in the initial period and then removed in the second). The boxes display means ± SE of all experiments performed. *P < 0.05.