title: Exercise training improves aortic endothelium-dependent vasorelaxation and determinants of nitric oxide bioavailability in spontaneously hypertensive rats.
abstract: The present study examined in vitro vasomotor function and expression of enzymes controlling nitric oxide (NO) bioavailability in thoracic aorta of adult male normotensive Wistar-Kyoto (WKY) and spontaneously hypertensive rats (SHR) that either remained sedentary (Sed) or performed 6 wk of moderate aerobic exercise training (Ex). Training efficacy was confirmed by elevated maximal activities of both citrate synthase (P = 0.0024) and beta-hydroxyacyl-CoA dehydrogenase (P = 0.0073) in the white gastrocnemius skeletal muscle of Ex vs. Sed rats. Systolic blood pressure was elevated in SHR vs. WKY (P < 0.0001) but was not affected by Ex. Despite enhanced endothelium-dependent relaxation to 10(-8) M ACh in SHR vs. WKY (P = 0.0061), maximal endothelium-dependent relaxation to 10(-4) M ACh was blunted in Sed SHR (48 +/- 12%) vs. Sed WKY (84 +/- 6%, P = 0.0067). Maximal endothelium-dependent relaxation to 10(-4) M ACh was completely restored in Ex SHR (93 +/- 9%) vs. Sed SHR (P = 0.0011). N(omega)-nitro-l-arginine abolished endothelium-dependent relaxation in all groups (P </= 0.0001) and caused equal vasocontraction to maximal ACh in Sed SHR and Ex SHR. Endothelium-independent relaxation to sodium nitroprusside was similar in all groups. Protein levels of endothelial NO synthase were higher in SHR vs. WKY (P = 0.0157) and in Ex vs. Sed (P = 0.0536). Protein levels of the prooxidant NAD(P)H oxidase subunit, gp91phox, were higher in SHR vs. WKY (P < 0.0001) and were diminished in Ex vs. Sed (P = 0.0557). Levels of the antioxidant SOD-1, -2, and catalase enzymes were lower in SHR vs. WKY (all P </= 0.0005) but were not altered by Ex. Thus elevated gp91phox-dependent oxidative stress and reduced antioxidant capacity likely contributed to impaired endothelium-dependent vasorelaxation in Sed SHR. Furthermore, reduced gp91phox-dependent oxidative stress and enhanced endothelial NO synthase-derived NO likely contributed to restored endothelium-dependent vasorelaxation in Ex SHR.
authors.affiliation: Department of Kinesiology, University of Waterloo, Waterloo, Ontario, Canada N2L 3G1.
authors.forename: Drew A
authors.initials: DA
authors.lastname: Graham
authors.forename: James W E
authors.initials: JW
authors.lastname: Rush
mesh_terms: D000818:Animals; D001011:Aorta; D001682:Biological Availability; D004730:Endothelium, Vascular / Q000187:drug effects / Q000502:physiology*; D008297:Male; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D009569:Nitric Oxide / Q000378:metabolism*; D009599:Nitroprusside / Q000494:pharmacology; D010805:Physical Conditioning, Animal; D051381:Rats; D011918:Rats, Inbred SHR; D011921:Rats, Inbred WKY; D014664:Vasodilation / Q000187:drug effects / Q000502:physiology*
chemical_list: D009599:Nitroprusside; D009569:Nitric Oxide; D019331:NG-Nitroarginine Methyl Ester