title: [Effects of intermittent +45 degrees head-up-tilt on mechanical parameters of femoral (correction of femural) bone in tail-suspended rats].
abstract: Objective. To study the effects of different intermittent +45 degrees head-up-tilt (IHUT) on tail-suspended rats. Method. 28 male SD rats were randomly and equally divided into: control group (C), tail-suspended group (S), IHUT 2 h group (H2), and IHUT 4 h group (H4). On the basis of tail-suspension to simulate weightlessness, H rats were given 2 h or 4 h IHUT each day. The effects of 3 wk IHUT on tail-suspended rats were evaluated by measuring physical and mechanical parameters of the femur. Result. Femoral mass (fresh, dry and ash), diameter, and density (fresh, except H2 group) in S, H2 and H4 rats were declined significantly compared to C rats (P<0.01 or P<0.05). Diameter (P<0.05) and density of femur (P<0.01) in H2 rats were significantly improved compared to S rats. Compared to C rats, the strength and stiffness of femora were obviously weakened (P<0.01) in S rats. Elastic load in H2 rats improved markedly (P<0.05) than those in S group; in H4 group, elastic load, maximum load, and bending toughness coefficient improved significantly (P< 0.01 or P<0.05). Conclusion. Using IHUT, mechanical parameters of weight bearing bones of tail-suspended rats can be improved apparently, by extending the exposure time, mechanical parameters can be improved.
authors.affiliation: Department of Aerospace Biodynamics, Faculty of Aerospace Medicine, The Fourth Military Medical University, Xi'an, China.
authors.forename: X S
authors.initials: XS
authors.lastname: Cao
authors.forename: X Y
authors.initials: XY
authors.lastname: Wu
authors.forename: Y H
authors.initials: YH
authors.lastname: Wu
authors.forename: L N
authors.initials: LN
authors.lastname: Zhang
authors.forename: L F
authors.initials: LF
authors.lastname: Zhang
mesh_terms: D000818:Animals; D001696:Biomechanical Phenomena; D001835:Body Weight; D015519:Bone Density / Q000502:physiology*; D004548:Elasticity; D005269:Femur / Q000502:physiology*; D018475:Head-Down Tilt; D019417:Hindlimb Suspension; D008297:Male; D011187:Posture / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D016474:Weight-Bearing; D018474:Weightlessness Simulation