Pharmacological characterization of rat renal medulla dopamine-sensitive cyclic adenosine monophosphate generating system.
The dopamine (DA) DA-1 and DA-2 receptors coupled to 3'-5'-cyclic adenosine monophosphate (cAMP) generating system were characterized in membrane particles of the rat kidney medulla. In confirmation of reports using central and other peripheral tissues, activation of DA-1 receptors with DA, apomorphine or SKF 82526 induced accumulation of cAMP. This effect was blocked by the DA-1 receptors antagonist SCH 23390 and by the other DA-2 receptor antagonists fluphenazine and haloperidol. DA-2 receptor responses coupled negatively to the cAMP generating system were obtained by incubating renal medulla membrane particles with DA or SKF 82526 together with SCH 23390. DA-2 receptor responses were also elicited with the receptor agonists quinpirole and bromocriptine in the absence of SCH 23390. These inhibitory effects on cAMP generation were abolished by the DA-2 receptor antagonist l-sulpiride. Our findings suggest that rat renal medulla contains DA DA-1 and DA-2 receptors similar to those found in brain and in other peripheral tissues. The physiological significance of these receptors, if any, should be established in future studies.
Amenta
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F
Dipartimento di Sanità Pubblica e Biologia Cellulare, Università Tor Vergata, Rome, Italy.
Ricci
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A
Vega
J A
JA
D000818:Animals; D001552:Benzazepines / Q000494:pharmacology; D000242:Cyclic AMP / Q000096:biosynthesis*; D004298:Dopamine / Q000494:pharmacology*; D007679:Kidney Medulla / Q000187:drug effects* / Q000378:metabolism; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D011954:Receptors, Dopamine / Q000032:analysis / Q000502:physiology; D017447:Receptors, Dopamine D1; D017448:Receptors, Dopamine D2
D001552:Benzazepines; D011954:Receptors, Dopamine; D017447:Receptors, Dopamine D1; D017448:Receptors, Dopamine D2; D000242:Cyclic AMP; D004298:Dopamine