Effect of age on rabbit aortic responses to relaxant endothelium-dependent and endothelium-independent agents.
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.
Chinellato
A
A
Department of Pharmacology, University of Padua, Italy.
Pandolfo
L
L
Ragazzi
E
E
Zambonin
M R
MR
Froldi
G
G
De Biasi
M
M
Caparrotta
L
L
Fassina
G
G
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
D000255:Adenosine Triphosphate; D012977:Sodium Nitrite; D009638:Norepinephrine