Aims: Endogenous ouabain is elevated in patients and experimental models of hypertension and is associated with elevated mortality. In this context, it is reasonable to assume that a new antihypertensive drug that inhibits the deleterious effects of endogenous ouabain may be a specific pharmacological tool for hypertension treatment. Here, we investigated the effects of rostafuroxin (ROSTA), an ouabain inhibitor, on SBP, endothelial dysfunction and oxidative stress in deoxycorticosterone acetate (DOCA)-salt rats.
Methods and results: A hypertensive model was established in uninephrectomized Wistar rats using DOCA-salt. After SBP stabilization, DOCA-salt rats were divided into two groups: DOCA-salt (control) and DOCA-salt treatment with ROSTA (1 mg/kg per day gavage, 3 weeks). The SBP was measured using the tail-cuff method, and vascular function was assessed in mesenteric-resistance arteries (MRAs) using a wire myograph. Nitric oxide and reactive oxygen species production were investigated. Western blot was performed to quantify protein expression. Our results indicated that ROSTA treatment decreased SBP, improved acetylcholine-induced relaxation via enhanced nitric oxide synthesis and bioavailability, decreased superoxide anion generation from NAD(P)H oxidase and cyclooxygenase-2 and reduced cytoplasmic tyrosine kinase Src phosphorylation without changes in Na+K+_ATPase activity in MRA from DOCA-salt rats.
Conclusion: This study reports the critical role of endogenous ouabain in volume-dependent hypertension. In MRA from DOCA-salt rats, the binding of endogenous ouabain to Na+K+-ATPase results in downstream c-SRC activation, oxidative stress and endothelial dysfunction. Endogenous ouabain is a putative target for the treatment of hypertension, and ROSTA may represent a novel therapeutic approach.
Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of Sao Paulo, Sao Paulo, Brazil
Correspondence to Luciana V. Rossoni, MD, PhD, Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of Sao Paulo, Av. Professor Lineu Prestes, 1524, sala 225, Sao Paulo, SP 05508-900, Brazil. Tel: +55 11 3091 8038; fax: +55 11 3091 7285; e-mail: email@example.com
Abbreviations: ANOVA, analysis of variance; COX, cyclooxygenase; COX-2, cyclooxygenase-2; cSRC, cytoplasmic tyrosine kinase Src; DAF-2, 4,5-diaminofluorescein diacetate; EDTA, ethylenediamine-tetraacetic acid; DHE, dihydroethidium; Emax, maximum response; eNOS, endothelial isoform of nitric oxide synthase; EO, endogenous ouabain; L-NAME, NG-nitro-L-arginine methyl ester; MRA, mesenteric-resistance arteries; NAD(P)H oxidase, nicotinamide adenine dinucleotide phosphate-oxidase; NO, nitric oxide; nNOS, neuronal isoform of nitric oxide synthase; NOS, nitric oxide synthase; OUA, ouabain; PAGE, polyacrylamide gel; pD2, negative logarithm of concentrations producing 50% of maximum response; PGH2, prostaglandin H2; ROS, reactive oxygen species; ROSTA, rostafuroxin; DOCA, deoxycorticosterone acetate; SBP, systolic blood pressure; SDS, sodium lauryl sulphate; SHR, spontaneously hypertensive rats; SOD, superoxide dismutase; TNF-α, tumor necrosis factor-α; TxA2, thromboxane A2
Received 1 July, 2013
Accepted 26 October, 2013