Renal blood-flow changes during renal nerve stimulation in rats treated with alpha-adrenergic and dopaminergic blockers.

1. Blood flow through the inner cortex and outer medulla of the rat kidney was measured by the hydrogen wash-out technique. 2. Renal nerve stimulation caused vasoconstriction in both cortex and medulla. This constriction was abolished or reduced by phenoxybenzamine (9 mumole/kg I.V.), phentolamine (100 n-mole/kg) or prazosin (1.5 mumole/kg). 3. After prazosin (6 mumole/kg I.V.), renal nerve stimulation caused small but significant renal cortical vasodilatation. This vasodilatation was reversed by sulpiride (0.7 mumole kg-1 min-1), but was unaffected by propranolol (10 mumole/kg) or atropine (4.3 mumole/kg). 4. These results indicate the existence of dopaminergic vasodilator nerves to the renal cortex of the rat.