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Dopamine stimulation of cAMP production in cultured opossum kidney cells
1Laboratory of Biological Chemistry, National Institute on Aging, National Institutes of Health, Baltimore, Maryland 21224.
Abstract:
Dopamine receptors have been identified in many tissues including the kidney. To establish an in vitro system as a model for dopamine action, we studied the effect of dopamine (DA) receptor agonists and antagonists on adenosine 3',5'-cyclic monophosphate (cAMP) formation in opossum kidney (OK) cells. The stimulation of cAMP production in these cells by dopamine was dose dependent, and markedly higher levels were observed in the presence of dopamine plus a phosphodiesterase inhibitor, 3-isobutyl-1-methylxanthine. Half-maximal stimulation was found with 1.15 +/- 0.22 microM dopamine. A DA1-receptor agonist, SKF 82526J, stimulated cAMP production, whereas a DA2-receptor agonist, Ly 171555, did not. The stimulatory effects of dopamine and SKF 82526J were abolished by a specific DA1-receptor antagonist, Sch 23390 with half-maximal inhibition concentrations of 1.24 +/- 0.18 and 4.0 +/- 0.5 nM, respectively. In contrast, the DA2-receptor antagonist, spiperone, had no inhibitory effect on dopamine- and SKF 82526J-stimulated cAMP production. Beta-Adrenergic antagonists failed to attenuate the stimulatory effects of dopamine and SKF 82526J on cAMP production. In addition, the beta-adrenergic receptor agonist, isoproterenol, did not stimulate cAMP production. These results suggest that the action of dopamine was not mediated through beta-adrenergic receptors. Furthermore, our results clearly demonstrated the existence of DA1-receptors linked to adenylate cyclase in OK cells.
Insights
Dopamine (DA) stimulates cyclic adenosine monophosphate (cAMP) production in kidney cells via DA1 receptors, not DA2 or beta-adrenergic receptors. This research identifies specific DA1-receptor pathways in kidney cells.
Area of Science:
- Pharmacology
- Cell Biology
- Nephrology
Background:
- Dopamine receptors are present in kidney tissues.
- Understanding dopamine's renal effects requires in vitro models.
Purpose of the Study:
- To investigate dopamine receptor subtypes mediating cyclic adenosine monophosphate (cAMP) formation in opossum kidney (OK) cells.
- To establish an in vitro model for dopamine action in the kidney.
Main Methods:
- Studied the effect of dopamine receptor agonists and antagonists on cAMP production in OK cells.
- Utilized a phosphodiesterase inhibitor (3-isobutyl-1-methylxanthine) to enhance cAMP levels.
- Dose-response and inhibition assays were performed with specific receptor ligands.
Main Results:
- Dopamine dose-dependently stimulated cAMP production in OK cells.
- A DA1-receptor agonist (SKF 82526J) increased cAMP, while a DA2-receptor agonist (Ly 171555) did not.
- DA1-receptor antagonist (Sch 23390) blocked dopamine and SKF 82526J effects; DA2 antagonist (spiperone) and beta-adrenergic antagonists had no effect.
Conclusions:
- Opossum kidney cells possess DA1-receptors linked to adenylate cyclase.
- Dopamine's action on cAMP in OK cells is mediated exclusively through DA1 receptors.
- These findings support the role of DA1 receptors in renal dopamine signaling.