Dopamine receptors mediating inhibition of the cyclic adenosine monophosphate generating system in the rat renal cortex.

1. In vitro addition of dopamine (DA) or of DA-1 receptor agonists increases 3'- 5'-cyclic adenosine monophosphate (cAMP) levels through the stimulation of DA-1 receptors. 2. Although receptor binding studies suggest the existence of DA-2 receptors in the renal cortex, the presence of DA receptors negatively coupled to cAMP generation (DA-2 effect) has not been so far characterized. 3. In this study we have shown that the addition of DA plus the selective DA-1 receptor antagonist SCH 23390 to membrane fractions of rat renal cortex decreased cAMP concentration below basal levels. 4. DA-2 receptor responses were also elicited with the DA-2 receptor agonists bromocriptine and quinpirole in the absence of SCH 23390. These inhibitory effects on cAMP generation were abolished by the DA-2 receptor antagonist 1-sulpiride. 5. The above findings are indicative of the existence in the rat renal cortex of DA-2 receptors showing an effect upon cAMP generation similar to that found in the brain and in several peripheral tissues.