A novel role for dopamine: inhibition of muscarinic cholinergic-stimulated phosphoinositide hydrolysis in rat brain cortical membranes.
Dopamine inhibited phosphoinositide breakdown as stimulated by carbachol in rat brain cortical membranes. The IC50 value was 14 +/- 2 microM for dopamine's inhibition of phosphatidylinositol hydrolysis as stimulated by 1 mM carbachol. The inhibition was found at low (0.1 microM), but not high (greater than 0.3 microM), concentrations of the non-hydrolyzable guanine nucleotide analog, GTP gamma S. Pharmacological characterization of the response indicated that the dopamine effects were mediated by D1 receptors. The assay conditions precluded any involvement of cyclic-AMP as a mediator of the dopamine response, and thus, a novel role is proposed for dopamine in cortex working through D1 receptors to inhibit phosphoinositide degradation.
Wallace
M A
MA
University of Tennessee, Department of Biochemistry, Memphis 38163.
Claro
E
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D015647:2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-benzazepine / Q000031:analogs & derivatives / Q000494:pharmacology; D000818:Animals; D001552:Benzazepines / Q000494:pharmacology; D002217:Carbachol / Q000494:pharmacology; D002540:Cerebral Cortex / Q000187:drug effects / Q000378:metabolism*; D004298:Dopamine / Q000494:pharmacology / Q000502:physiology*; D066298:In Vitro Techniques; D008297:Male; D010716:Phosphatidylinositols / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D011954:Receptors, Dopamine / Q000187:drug effects / Q000502:physiology*; D017447:Receptors, Dopamine D1; D011976:Receptors, Muscarinic / Q000187:drug effects / Q000502:physiology*; D010738:Type C Phospholipases / Q000378:metabolism*
D015647:2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-benzazepine; D001552:Benzazepines; D002217:Carbachol; D004298:Dopamine; D010716:Phosphatidylinositols; D011954:Receptors, Dopamine; D017447:Receptors, Dopamine D1; D011976:Receptors, Muscarinic; D010738:Type C Phospholipases; C044846:SKF83566