Dopamine via activation of renal D₁-like receptors inhibits the activities of Na, K - ATPase and Na/H exchanger and subsequently increases sodium excretion. Decreased renal dopamine production and sodium excretion are associated with hyperglycemic conditions. We have earlier reported D₁-like receptor G-protein uncoupling and reduced response to D₁-like receptor activation in streptozotocin (STZ) treated hyperglycemic rats. The present study was designed to test the hypothesis that oxidative stress associated with hyperglycemia increases basal D₁-like receptor serine phosphorylation via activation of protein kinase C (PKC) - G-protein receptor kinases (GRK ) pathway resulting in loss of D₁-like receptor-G-protein coupling and function. We observed that STZ-treated rats exhibited oxidative stress as evidenced by increased lipid peroxidation. Furthermore, PKC activity and expression of PKC _I and isoforms was increased in STZ-treated rats. In addition, in STZ-treated rats there was increased GRK2 translocation to proximal tubular membrane and increased basal serine D₁-like receptor phosphorylation. Supplementation with antioxidant tempol, lowered oxidative stress in STZ-treated rats and led to normalization of PKC activity, and prevented GRK2 translocation. Furthermore, tempol supplementation in STZ-treated rats restored D₁-like receptor-G-protein coupling and inhibition of Na,K-ATPase activity upon D₁-like receptor agonist stimulation. The functional consequence was the restoration of the natriuretic response to D₁-like receptor activation. We conclude that oxidative stress associated with hyperglycemia causes an increase in activity and expression of PKC. This leads to translocation of GRK2, subsequent phosphorylation of D₁-like receptor, its uncoupling from G-proteins and loss of responsiveness to agonist stimulation.