Superoxide dismutase mimetics do not reduce JCl. CCDs from aldosterone-treated mice were perfused in vitro in the presence (A and C) or in the absence (B) of angiotensin II (10 nM) in the bath. A and B: JCl was measured in individual tubules before and then after the application of the superoxide mimetic tempol (4-hydroxy 2,2,6,6,-tetramethyl piperidinoxyl; 50 μM) to the bath. Solid lines show individual tubules. Dashed lines show experiments conducted in reverse order (i.e., tempol was applied in the first period and then removed in the second). Open squares show means ± SE. C: JCl was measured in separate tubules after at least 30-min incubation with tempol (50 μM) or vehicle present in both the bath and luminal solution. The bar graph shows means ± SE.