Dopamine D1 receptor (D1R) phosphorylation in renal proximal tubular membranes from V-, 1% NaCl-, BSO-, and BSO + NaCl-treated rats. Membrane D1 receptors were immunoprecipitated, followed by immunoblotting for D1 receptor protein (D1R ∼52 kDa) and serine phosphorylation (D1R-phospho). Blots shown are a single experiment, representative of 6–8 individual experiments, and bars (D1R-phospho/D1R protein) represent means ± SE. *P < 0.05 vs. V and #P < 0.05 vs. NaCl, using 1-way ANOVA followed by post hoc Newman-Keuls multiple comparison test.