Production and excretion of dopamine by the isolated perfused rat kidney.

Renal catecholamine concentrations and urinary dopamine excretion from the isolated perfused kidney were measured in intact and peripherally sympathectomized rats. Urinary dopamine excretion was not diminished by sympathectomy, was increased by l-dopa (but not tyrosine or dopamine 4-O-sulphate) in the perfusate and was virtually abolished by prior treatment with the dopa decarboxylase inhibitor, carbidopa. These results confirm the importance of renal extraneuronal dopamine production, from circulating l-dopa, as a contributor to urinary dopamine excretion.