title: Oxidative stress causes renal dopamine D1 receptor dysfunction and salt-sensitive hypertension in Sprague-Dawley rats.
abstract: Renal dopamine plays an important role in maintaining sodium homeostasis and blood pressure (BP) during increased sodium intake. The present study was carried out to determine whether renal dopamine D1 receptor (D1R) dysfunction contributes to increase in salt sensitivity during oxidative stress. Male Sprague-Dawley rats, divided into various groups, received tap water (vehicle); 1% NaCl (high salt [HS]); L-buthionine sulfoximine (BSO), an oxidant; and HS plus BSO with or without Tempol, an antioxidant, for 12 days. Compared with vehicle, HS intake increased urinary dopamine production and decreased basal renal Na/K-ATPase activity but did not affect BP. BSO-treated rats exhibited oxidative stress and a mild increase in BP. In these rats, D1R expression and G protein coupling were reduced, and SKF38393, a D1R agonist, failed to inhibit Na/K-ATPase activity and promote sodium excretion. Concomitant administration of BSO and HS caused oxidative stress, D1R dysfunction, and a marked increase in BP. Although renal dopamine production was increased, it failed to reduce the basal Na/K-ATPase activity in these animals. Treatment of BSO plus HS rats with Tempol decreased oxidative stress and restored endogenous, as well as exogenous, D1R agonist-mediated Na/K-ATPase inhibition and normalized BP. In conclusion, during HS intake, the increased dopamine production via Na/K-ATPase inhibition prevents an increase in BP. During oxidative stress, D1R function is defective, and there is mild hypertension. However, in the presence of oxidative stress, HS intake causes marked elevation in BP, which results from a defective renal D1R function leading to the failure of dopamine to inhibit Na/K-ATPase and promote sodium excretion.
authors.affiliation: Heart and Kidney Institute, College of Pharmacy, University of Houston, 4800 Calhoun Rd, Houston, TX 77204, USA. abanday@uh.edu
authors.forename: Anees A
authors.initials: AA
authors.lastname: Banday
authors.forename: Yuen-Sum
authors.initials: YS
authors.lastname: Lau
authors.forename: Mustafa F
authors.initials: MF
authors.lastname: Lokhandwala
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; D000975:Antioxidants / Q000494:pharmacology; D019328:Buthionine Sulfoximine / Q000494:pharmacology; D003497:Cyclic N-Oxides / Q000494:pharmacology; D004231:Diuresis; D004298:Dopamine / Q000652:urine; D018491:Dopamine Agonists / Q000494:pharmacology; D004789:Enzyme Activation; D019204:GTP-Binding Proteins / Q000378:metabolism; D006973:Hypertension / Q000139:chemically induced* / Q000378:metabolism* / Q000503:physiopathology; D007668:Kidney / Q000201:enzymology / Q000378:metabolism* / Q000503:physiopathology; D007687:Kidney Tubules, Proximal / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D008297:Male; D008566:Membranes / Q000378:metabolism; D009318:Natriuresis; D016877:Oxidants / Q000494:pharmacology; D018384:Oxidative Stress / Q000187:drug effects; D051381:Rats; D017207:Rats, Sprague-Dawley; D017447:Receptors, Dopamine D1 / Q000819:agonists / Q000378:metabolism*; D012965:Sodium Chloride; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism; D013113:Spin Labels
chemical_list: D000975:Antioxidants; D003497:Cyclic N-Oxides; D018491:Dopamine Agonists; D016877:Oxidants; D017447:Receptors, Dopamine D1; D013113:Spin Labels; D012965:Sodium Chloride; D019328:Buthionine Sulfoximine; D015647:2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-benzazepine; D019204:GTP-Binding Proteins; D000262:Adenylyl Cyclases; D000254:Sodium-Potassium-Exchanging ATPase; C001803:tempol; D004298:Dopamine