A: endothelial nitric oxide synthase 3 (NOS3) expression in renal proximal tubules from V-, 1% NaCl-, BSO-, and BSO + NaCl-treated rats. Blots (NOS3 ∼140 kDa and GAPDH ∼45 kDa) shown are a single experiment, representative of 6–8 individual experiments, and bars (NOS3/GAPDH) represent means ± SE. Proximal tubular homogenate (50 μg protein for NOS3 and 10 μg protein for GAPDH) was used for immunobloting. *P < 0.05 vs. V, using 1-way ANOVA followed by post hoc Newman-Keuls multiple comparison test. B: GAPDH band intensity with varying protein concentrations. Lane 1: markers; lane 2: 1 μg protein; lane 3: 2 μg protein; lane 4: 4 μg protein; lane 5: 6 μg protein; lane 6: 8 μg protein; lane 7: 10 μg protein; lane 8: 10 μg protein but antibody preincubated with antigen; lane 9: blank well.