Aging alters mechanical and contractile properties of the Fisher 344/Nnia X Norway/Binia rat aorta.
Vascular mechanical and contractile properties were compared in adult (6 months old) and very-aged (36 months old) Fischer 344/NNiaHSd X Brown Norway/BiNia (F344/NXBN) rats. Our previous work has indicated that aging is associated with aortic medial thickening. This morphological alteration was accompanied by a leftward shift in the aortic stress/strain curve indicating increased vessel stiffness in very-aged animals. Disruption of the endothelium as well as pretreatment of tissues with the nitric oxide (NO) donor sodium nitroprusside eliminated differences, suggesting a link between deficient endothelial NO release and reduced compliance in very-aged aortae. In addition, the Rho kinase inhibitor Y-27632 increased vessel compliance in both adult and very-aged tissues suggesting that the Rho cascade contributed to the stress/strain relationship. Maximal force developed in response to high potassium (K(+)) was reduced by approximately 70% in intact and endothelium-denuded aortae from very-aged rats. In contrast to contractile force development, calcium-dependent stress relaxation was increased in very-aged aorta. Finally, gel electrophoresis indicated a significantly higher tissue content of myosin heavy chain and a higher ratio of SM1/SM2 isoforms with aging. The results suggest multiple molecular changes with aging, which may be expected to alter vascular tissue function.
Blough
E R
ER
Department of Biological Sciences, Laboratory of Molecular Physiology, Marshall University, Huntington, WV 25755-1090, USA. blough@marshall.edu
Rice
K M
KM
Desai
D H
DH
Wehner
P
P
Wright
G L
GL
D000375:Aging / Q000502:physiology*; D000577:Amides / Q000494:pharmacology; D000818:Animals; D001011:Aorta / Q000187:drug effects / Q000502:physiology*; D001696:Biomechanical Phenomena; D004730:Endothelium, Vascular / Q000187:drug effects / Q000502:physiology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D008297:Male; D023421:Models, Animal; D009119:Muscle Contraction / Q000187:drug effects / Q000502:physiology*; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000502:physiology; D018995:Myosin Heavy Chains / Q000378:metabolism; D009569:Nitric Oxide / Q000378:metabolism; D020030:Nitric Oxide Donors / Q000494:pharmacology; D009599:Nitroprusside / Q000494:pharmacology; D011188:Potassium / Q000494:pharmacology; D011725:Pyridines / Q000494:pharmacology; D051381:Rats; D011914:Rats, Inbred BN; D011916:Rats, Inbred F344
D000577:Amides; D004791:Enzyme Inhibitors; D020030:Nitric Oxide Donors; D011725:Pyridines; C108830:Y 27632; D009599:Nitroprusside; D009569:Nitric Oxide; D018995:Myosin Heavy Chains; D011188:Potassium