title: High salt intake does not produce additional impairment in the coronary artery relaxation of spontaneously hypertensive aged rats.
abstract: The effect of a salt-based diet on the coronary responsiveness in aged hypertensive rats (SHR) still is unclear. We investigated the effects of high salt intake on the relaxation properties of coronary arteries of aged SHRs. Male SHR (32 week-old) received drinking water (SHR) or 1% NaCl solution (SHR-Salt) for 8 weeks. Isolated coronary segments were subjected to concentration-response curves to acetylcholine (ACh) in the presence or absence of L-NAME (100 μM), enalaprilate (10 μM), losartan (10 μM), and spironolactone (100 μM). Salt intake did not increase blood pressure in old SHRs, but caused ventricular hypertrophy. The endothelium-dependent relaxation in SHRs was lower than in Wistar rats. However, salt intake did not add further impairment. Both enalaprilate and losartan reduced the vasodilator response in coronary arteries from Wistar, but did not affect SHR-salt rats. Conversely, losartan attenuated the impaired ACh relaxation observed in SHR. Spironolactone reduced the relaxation induced by ACh in coronary arteries from Wistar rats but not in SHR. The renin-angiotensin-aldosterone system participates in the impaired coronary relaxation in aged SHR, but does not partake in this deleterious effect under increased salt intake, indicating that age could differentiate the effects of high sodium intake in coronary arteries of SHR.
authors.affiliation: Department of Physiological Sciences, Federal University of Espirito Santo, Vitoria, Brazil.
authors.forename: Maylla R
authors.initials: MR
authors.lastname: Simões
authors.forename: Lorena B
authors.initials: LB
authors.lastname: Furieri
authors.forename: Ludimila
authors.initials: L
authors.lastname: Forechi
authors.forename: Marcelo P
authors.initials: MP
authors.lastname: Baldo
authors.forename: Sérgio L
authors.initials: SL
authors.lastname: Rodrigues
authors.forename: Mercedes
authors.initials: M
authors.lastname: Salaices
authors.forename: Dalton V
authors.initials: DV
authors.lastname: Vassallo
authors.forename: José Geraldo
authors.initials: JG
authors.lastname: Mill
mesh_terms: D000818:Animals; D003331:Coronary Vessels / Q000187:drug effects* / Q000503:physiopathology; D008297:Male; D051381:Rats; D011918:Rats, Inbred SHR; D017208:Rats, Wistar; D017673:Sodium Chloride, Dietary / Q000008:administration & dosage* / Q000494:pharmacology; D014664:Vasodilation
chemical_list: D017673:Sodium Chloride, Dietary
keywords: Aging; Coronary dysfunction; High salt intake; Hypertension