title: Simulated microgravity effects on the rat carotid and femoral arteries: role of contractile protein expression and mechanical properties of the vessel wall.
abstract: The goal of this study was to determine the effects of microgravity on myofilament protein expression and both passive and active length-force relationships in carotid and femoral arteries. Microgravity was simulated by 20-day hindlimb unweighting (HU) in Wistar male rats, and carotid and femoral artery segments were isolated from both HU and control (CTL) rats for Western blot and length-force analysis. Western blots revealed that HU significantly decreased myosin light chain-20 (MLC-20) protein levels in both carotid and femoral arteries and decreased myosin heavy chain (MHC) in femoral artery. alpha-Actin levels were not altered by HU treatment in either artery. Length-force analysis demonstrated that HU did not change either passive or active length-force relationships in the femoral artery. HU-treated arterial rings developed significantly less force to 100 mM K(+) than CTL, but optimal lengths were identical. In the carotid artery, length-active force curves were identical for both CTL and HU; however the length-passive force curve for HU-treated rings exhibited a steeper slope than CTL, suggesting decreased compliance of the artery wall. In conclusion, our data suggest that the HU-induced decreases in both MLC-20 and MHC in femoral artery are responsible for the decreased contraction to 100 mM K(+) in HU-treated femoral artery rings. In the carotid artery, the HU-induced decrease in vessel wall compliance may counter any decrease in contractility caused by the decreased MLC-20 levels.
authors.affiliation: Department of Pharmacology, School of Medicine, University of California, Irvine, California 92697-4625, USA.
authors.forename: Sunup
authors.initials: S
authors.lastname: Hwang
authors.forename: Stanislav A
authors.initials: SA
authors.lastname: Shelkovnikov
authors.forename: Ralph E
authors.initials: RE
authors.lastname: Purdy
mesh_terms: D000222:Adaptation, Physiological / Q000502:physiology; D000818:Animals; D001696:Biomechanical Phenomena / Q000379:methods; D002339:Carotid Arteries / Q000502:physiology*; D004548:Elasticity; D005263:Femoral Artery / Q000502:physiology*; D015870:Gene Expression / Q000502:physiology; D019417:Hindlimb Suspension; D008297:Male; D040542:Mechanotransduction, Cellular / Q000502:physiology; D020409:Molecular Motor Proteins / Q000378:metabolism; D009119:Muscle Contraction / Q000502:physiology*; D009124:Muscle Proteins / Q000378:metabolism*; D009131:Muscle, Smooth, Vascular / Q000502:physiology*; D051381:Rats; D017208:Rats, Wistar; D013314:Stress, Mechanical; D014661:Vasoconstriction / Q000502:physiology; D018474:Weightlessness Simulation / Q000379:methods*
chemical_list: D020409:Molecular Motor Proteins; D009124:Muscle Proteins