title: Dopamine acutely decreases type 3 Na(+)/H(+) exchanger activity in renal OK cells through the activation of protein kinases A and C signalling cascades.
abstract: Dopamine D(1)-mediated inhibition of Na(+),K(+)-ATPase activity in opossum kidney (OK) cells involves the sequential activation of the adenylyl cyclase-protein kinase A (PKA) and the phospholipase C-protein kinase C (PKC) pathways. The present study evaluated the signalling cascades involved in dopamine-mediated inhibition of Na(+)/H(+) exchanger isoform 3 (NHE3) in OK cells. The transport kinetics displayed a simple Michaelis-Menten relationship for extracellular Na(+) of 25+/-6 mM. Dopamine and the dopamine D(1)-like receptor agonist SKF 38393 ((+/-)-1-phenyl-2,3,4,5-tetrahydro-(1H)-3-benzazepine-7,8-diol) inhibited NHE3 activity in a concentration-dependent manner; the dopamine D(2)-like receptor agonist quinerolane was devoid of effect. The SKF 38393-mediated inhibition of NHE3 was prevented either by the dopamine D(1)-like receptor antagonist SKF 83566 ((+/-)-7-Bromo-8-8-hydroxy-3 methyl-1-phenyl-2,3,4,5-tetrahydro-1H-3-benzazepine; 1 microM), overnight treatment with cholera toxin (500 ng/ml), the PKA antagonist H-89 (N-(2-[p-bromocinnamylamino]ethyl)-5 isoquinolinesulfonamide hydrochloride; 10 microM), the PKC antagonist chelerythrine (1 microM), or the phospholipase C inhibitor U-73,122 (1-(6-[(17beta]-3-methoxyestra-1,3,5[10]-trien-17-yl) amino] hexyl)-1H-pyrrole-2,5-dione; 3 microM). In addition, dibutyril cAMP (dB-cAMP; 500 microM) was found to increase phospholipase C activity, both in membranes and in cytosol from OK cells; in contrast, phorbol-12,13-dibutyrate (PDB) (1 microM) did not have a significant effect on phospholipase C activity. Pre-treatment of OK cells with the anti-G(s)alpha antibody, but not the anti-G(q/11)alpha antibody, blunted the inhibitory effect of SKF 38393 on NHE3 activity. It is concluded that dopamine D(1)-mediated inhibition of NHE3 in renal OK cells involves both adenylyl cyclase-PKA and the phospholipase C-PKC pathways, a mechanism similar to that described for Na(+),K(+)-ATPase.
authors.affiliation: Institute of Pharmacology and Therapeutics, Faculty of Medicine, Porto 4200-319, Portugal.
authors.forename: Pedro
authors.initials: P
authors.lastname: Gomes
authors.forename: Patrício
authors.initials: P
authors.lastname: Soares-da-Silva
mesh_terms: D015647:2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-benzazepine / Q000494:pharmacology; D000262:Adenylyl Cyclases / Q000378:metabolism; D000818:Animals; D017868:Cyclic AMP-Dependent Protein Kinases / Q000502:physiology*; D004298:Dopamine / Q000494:pharmacology*; D018491:Dopamine Agonists / Q000494:pharmacology; D006863:Hydrogen-Ion Concentration; D007668:Kidney / Q000187:drug effects / Q000378:metabolism*; D007700:Kinetics; D009893:Opossums / Q000502:physiology*; D011493:Protein Kinase C / Q000502:physiology*; D017447:Receptors, Dopamine D1 / Q000187:drug effects; D017448:Receptors, Dopamine D2 / Q000187:drug effects; D015398:Signal Transduction / Q000187:drug effects*; D000074083:Sodium-Hydrogen Exchanger 3; D017923:Sodium-Hydrogen Exchangers / Q000037:antagonists & inhibitors / Q000378:metabolism*; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism; D010738:Type C Phospholipases / Q000378:metabolism
chemical_list: D018491:Dopamine Agonists; D017447:Receptors, Dopamine D1; D017448:Receptors, Dopamine D2; D000074083:Sodium-Hydrogen Exchanger 3; D017923:Sodium-Hydrogen Exchangers; D015647:2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-benzazepine; D017868:Cyclic AMP-Dependent Protein Kinases; D011493:Protein Kinase C; D010738:Type C Phospholipases; D000262:Adenylyl Cyclases; D000254:Sodium-Potassium-Exchanging ATPase; D004298:Dopamine