Evidence that dopaminergic sympathetic axons supply the medullary arterioles of human kidney.

The ability of the kidney to excrete sodium appears to depend on release of dopamine from intrarenal sources. In the present study, we have used immunohistochemistry to examine the possibility that renal dopaminergic nerves constitute one of these sources. We found that the sympathetic axons supplying cortical structures in human kidney contain tyrosine hydroxylase-like immunoreactivity but lack DOPA decarboxylase-like immunoreactivity. By contrast, the vasa recta arterioles of the renal medulla are supplied by varicose tyrosine hydroxylase-positive nerve fibres, some of which also contain DOPA decarboxylase. As DOPA decarboxylase has been demonstrated in other situations to be a selective marker for dopaminergic terminal axons, our results suggest the innervation of renal medullary blood vessels in man by both noradrenergic and dopaminergic sympathetic nerves.