title: Effect of age on rabbit aortic responses to relaxant endothelium-dependent and endothelium-independent agents.
abstract: The aim of this study was to evaluate the effects of aging on endothelium-dependent and endothelium-independent relaxation of rabbit thoracic aorta from New Zealand white rabbits aged 4-6 and 7-12 months. The contractile response to noradrenaline (NA) decreased with increasing age, but NA [EC50] did not vary significantly. Acetylcholine (Ach)-induced relaxation of aortic rings precontracted with NA [EC50] did not change significantly with increasing age. The relaxation induced by ATP of aortic rings, precontracted with NA [EC50], was significantly greater in young than in adult rabbits. This difference between young and adult animals became more evident in aortic rings deprived of endothelium: in adult animals, the ATP-induced relaxation of aortic rings with endothelium was significantly greater than in the rings without endothelium. The endothelium-independent relaxation by sodium nitrite (NaNO2) at lower concentrations was significantly greater in young than in adult rabbit aortic rings precontracted with NA [EC50]. Concluding, the age-induced changes in vascular response in male New Zealand white rabbits are related to an impaired mechanism at smooth muscle level.
authors.affiliation: Department of Pharmacology, University of Padua, Italy.
authors.forename: A
authors.initials: A
authors.lastname: Chinellato
authors.forename: L
authors.initials: L
authors.lastname: Pandolfo
authors.forename: E
authors.initials: E
authors.lastname: Ragazzi
authors.forename: M R
authors.initials: MR
authors.lastname: Zambonin
authors.forename: G
authors.initials: G
authors.lastname: Froldi
authors.forename: M
authors.initials: M
authors.lastname: De Biasi
authors.forename: L
authors.initials: L
authors.lastname: Caparrotta
authors.forename: G
authors.initials: G
authors.lastname: Fassina
mesh_terms: D000255:Adenosine Triphosphate / Q000494:pharmacology; D000375:Aging / Q000502:physiology*; D000818:Animals; D001013:Aorta, Thoracic / Q000502:physiology*; D004730:Endothelium, Vascular / Q000502:physiology*; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects; D009126:Muscle Relaxation / Q000187:drug effects / Q000502:physiology*; D009638:Norepinephrine / Q000494:pharmacology; D011817:Rabbits; D012977:Sodium Nitrite / Q000494:pharmacology; D014664:Vasodilation / Q000187:drug effects
chemical_list: D000255:Adenosine Triphosphate; D012977:Sodium Nitrite; D009638:Norepinephrine