title: Structural remodeling of coronary resistance arteries: effects of age and exercise training.
abstract: Age is known to induce remodeling and stiffening of large-conduit arteries; however, little is known of the effects of age on remodeling and mechanical properties of coronary resistance arteries. We employed a rat model of aging to investigate whether 1) age increases wall thickness and stiffness of coronary resistance arteries, and 2) exercise training reverses putative age-induced increases in wall thickness and stiffness of coronary resistance arteries. Young (4 mo) and old (21 mo) Fischer 344 rats remained sedentary or underwent 10 wk of treadmill exercise training. Coronary resistance arteries were isolated for determination of wall-to-lumen ratio, effective elastic modulus, and active and passive responses to changes in intraluminal pressure. Elastin and collagen content of the vascular wall were assessed histologically. Wall-to-lumen ratio increased with age, but this increase was reversed by exercise training. In contrast, age reduced stiffness, and exercise training increased stiffness in coronary resistance arteries from old rats. Myogenic responsiveness was reduced with age and restored by exercise training. Collagen-to-elastin ratio (C/E) of the wall did not change with age and was reduced with exercise training in arteries from old rats. Thus age induces hypertrophic remodeling of the vessel wall and reduces the stiffness and myogenic function of coronary resistance arteries. Exercise training reduces wall-to-lumen ratio, increases wall stiffness, and restores myogenic function in aged coronary resistance arteries. The restorative effect of exercise training on myogenic function of coronary resistance arteries may be due to both changes in vascular smooth muscle phenotype and expression of extracellular matrix proteins.
authors: Department of Materials Science and Engineering, University of Florida, Gainesville, Florida; Department of Mechanical and Aerospace Engineering, University of Florida, Gainesville, Florida; Department of Materials Science and Engineering, Stanford University, Stanford, California.
authors: Mina A
authors: MA
authors: Hanna
authors: Department of Mechanical and Aerospace Engineering, University of Florida, Gainesville, Florida;
authors: Curtis R
authors: CR
authors: Taylor
authors: Department of Physiology and Functional Genomics, University of Florida, Gainesville, Florida;
authors: Bei
authors: B
authors: Chen
authors: Department of Materials Science and Engineering, University of Florida, Gainesville, Florida;
authors: Hae-Sun
authors: HS
authors: La
authors: Department of Materials Science and Engineering, University of Florida, Gainesville, Florida;
authors: Joshua J
authors: JJ
authors: Maraj
authors: Department of Physiology and Functional Genomics, University of Florida, Gainesville, Florida;
authors: Cody R
authors: CR
authors: Kilar
authors: Department of Applied Physiology and Kinesiology and the Center for Exercise Science, University of Florida, Gainesville, Florida;
authors: Bradley J
authors: BJ
authors: Behnke
authors: Department of Applied Physiology and Kinesiology and the Center for Exercise Science, University of Florida, Gainesville, Florida;
authors: Michael D
authors: MD
authors: Delp
authors: Department of Physiology and Functional Genomics, University of Florida, Gainesville, Florida; judy.delp@med.fsu.edu.
authors: Judy M
authors: JM
authors: Muller-Delp
mesh_terms: D000375:Aging / Q000502:physiology*; D000818:Animals; D003094:Collagen / Q000378:metabolism; D003331:Coronary Vessels / Q000378:metabolism / Q000502:physiology*; D004549:Elastin / Q000378:metabolism; D066298:In Vitro Techniques; D008297:Male; D009119:Muscle Contraction / Q000502:physiology; D036103:Nanotechnology; D010805:Physical Conditioning, Animal / Q000502:physiology*; D051381:Rats; D011916:Rats, Inbred F344; D014655:Vascular Resistance / Q000502:physiology*; D059289:Vascular Stiffness / Q000502:physiology
chemical_list: D003094:Collagen; D004549:Elastin
keywords: Verhoeff; elastic modulus; hypertrophy; nanoindentation; van Geison