Renal dopamine, synthesized by proximal tubules, plays an important role in the regulation of renal sodium excretion. Although the renal dopaminergic system has been extensively investigated both in physiological and pathological situations, the mechanisms whereby dopamine is stored and secreted by proximal tubule cells remain obscure. In the present study we investigated whether vesicular monoamine transporters (VMAT)1 and 2, which participate to amine storing and secretion, are expressed in rat renal proximal tubules and we defined their involvement in dopamine secretion. By combining RT-PCR, Western blot and immunocytochemistry we showed that VMAT1 is the predominant isoform expressed in isolated proximal tubule cells. These results were confirmed by immunohistochemistry analysis of rat renal cortex showing that VMAT1 was found in proximal tubules but not in glomeruli. Functional studies showed that, as previously reported for VMAT-dependent amine transporters, dopamine release by cultured proximal tubule cells was partially inhibited by disruption of intracellular H⁺ gradient. In addition, dopamine secretion was prevented by the VMAT1/VMAT2 inhibitor reserpine but not by the VMAT2 inhibitor tetrabenazine. Finally, we demonstrated that tubular VMAT1 mRNA and protein expression were significantly up-regulated during high sodium diet. In conclusion, our results show for the first time the expression of a vesicular monoamine transporter in the renal proximal tubule and its involvement in regulation of dopamine secretion. These data represent the first step toward the comprehension of the role of this transporter in renal dopamine handling and its involvement in pathological situations.