title: Dietary soy modulates endothelium-dependent relaxation in aged male rats: Increased agonist-induced endothelium-derived hyperpolarising factor and basal nitric oxide activity.
abstract: We examined the effects of dietary soy on the contributions of endothelium-derived hyperpolarising factor (EDHF), nitric oxide (NO), and oxidative stress to vascular tone in isolated aortic rings and small mesenteric and pulmonary arteries in vitro. Male Wistar rats were either continuously fed a soy-deficient diet (SD) or switched from a soy-deficient diet to a soy-rich one for 6 months (SW). Contractile responses were generally smaller in arteries from SW rats. In mesenteric arteries, this difference was blunted by L-NAME, but not by charybdotoxin and apamin. Preconstricted SW mesenteric arteries were more sensitive to acetylcholine (ACh) than SD ones. This difference was unaffected by L-NAME but was abolished by charybdotoxin and apamin. Exogenous superoxide dismutase (SOD) and catalase induced powerful relaxations in aortic rings, which were smaller in those from SW rats. In mesenteric and pulmonary arteries, however, they partially inhibited ACh-mediated relaxation, and enhanced PGF(2alpha)-mediated contraction, respectively. Our results suggest that feeding aging male rats a soy-rich diet results in improved agonist-mediated EDHF production and a generalized reduction in contractile force, which is partly due to elevated basal NO. Our data also suggest a prorelaxant role for endogenous H(2)O(2) in small arteries, which is modulated by a soy diet.
authors.affiliation: King's College London, Division of Asthma, Allergy and Lung Biology, School of Medicine, London SE1 1UL, UK. greg.knock@kcl.ac.uk <greg.knock@kcl.ac.uk>
authors.forename: Greg A
authors.initials: GA
authors.lastname: Knock
authors.forename: Katharina
authors.initials: K
authors.lastname: Mahn
authors.forename: Giovanni E
authors.initials: GE
authors.lastname: Mann
authors.forename: Jeremy P T
authors.initials: JP
authors.lastname: Ward
authors.forename: Philip I
authors.initials: PI
authors.lastname: Aaronson
mesh_terms: D000109:Acetylcholine / Q000494:pharmacology; D000375:Aging; D000818:Animals; D001030:Apamin / Q000494:pharmacology; D001685:Biological Factors / Q000819:agonists* / Q000378:metabolism; D018999:Charybdotoxin / Q000494:pharmacology; D004730:Endothelium, Vascular / Q000378:metabolism*; D008297:Male; D008638:Mesenteric Arteries / Q000187:drug effects / Q000378:metabolism; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D009569:Nitric Oxide / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D017382:Reactive Oxygen Species; D030262:Soybean Proteins / Q000494:pharmacology*; D013025:Glycine max / Q000378:metabolism*
chemical_list: D001685:Biological Factors; D017382:Reactive Oxygen Species; D030262:Soybean Proteins; C067410:endothelium-dependent hyperpolarization factor; D018999:Charybdotoxin; D001030:Apamin; D009569:Nitric Oxide; D000109:Acetylcholine; D019331:NG-Nitroarginine Methyl Ester