Tandem Requirement for Full Renal D 1 R and D 5 R Activity

The peripheral dopaminergic system promotes the maintenance of blood pressure homeostasis by engendering natriuresis, mainly through the renal DR and DR receptors. This effect is most apparent under conditions of moderate body sodium excess. Human and rodent renal proximal tubules express both receptors, which share common structural features and pharmacological profiles. Genetic ablation of either receptor in the kidney results in hypertension in mice. In this study, we demonstrated that in renal proximal tubules, these two receptors colocalized, co-immunoprecipitated, co-segregated in lipid rafts, and heterodimerized with one another, which was enhanced by treatment with the DR/DR agonist fenoldopam (1 μM, 30 min). Gene silencing via antisense oligonucleotides in renal proximal tubule cells abrogated cAMP production and sodium transport in response to fenoldopam. Our results highlight the cooperation and co-dependence of these two receptors through heterodimerization in renal proximal tubule cells.