VASCULAR BIOLOGY AND SIMULATED MICROGRAVITY

后肢减重(HU)是一种用来模拟选择条件的模型 微重力。暴露于HU的大鼠运动能力下降 以最大摄氧量(最大摄氧量)较低为特征。这个 这种去条件性作用的机制涉及一种能力受损的 在运动过程中增加骨骼肌血流量。的总体目标是 本研究旨在确定内皮依赖性血管扩张剂 HU大鼠的反应受损。此外，我们还将确定是否 HU导致血管流量的下降和潜在的 后肢的毛细血管交换。将解决五个具体目标。 目的#1将确定HU对内皮潜能的影响- 导管动脉的依赖性血管扩张与微血管阻力 从足底和比目鱼肌分离出的动脉。目标#2将 检测HU对内皮细胞一氧化氮表达的影响 一氧化氮合酶(EcNODS)在导管和阻力动脉中的表达。目标#3将 测定HU对输卵管内皮型一氧化氮合酶mRNA含量及抗性的影响 动脉。目标4将确定ecNOS减少的时间进程 活性和mRNA水平。目标5将确定是否暴露于HU 减少血管流量和毛细血管交换的潜力。 据推测，内皮依赖性血管扩张将受到损害。 在HU染毒大鼠分离的血管中。

Hindlimb unweighing (HU) is a model used to simulate select condition of microgravity. Rats exposed to HU exhibit reductions in exercise capacity characterized by lower measures of maximal oxygen uptake (VO2 max). The mechanism for this deconditioning effect involves an impaired ability to increase skeletal muscle blood flow during exercise. The general aim of this study is to determine whether endothelium-dependent vasodilator responses are impaired in HU rats. In addition we will determine whether HU causes a decrease in vascular flow capacity and the potential for capillary exchange in the hindlimbs. Five specific aims will be addressed. Aim #1 will determine the effects of HU on the potential for endothelium- dependent vasodilation in a conduit artery and microvascular resistance arteries isolated from the plantaris and soleus muscles. Aim #2 will determine the effect of HU on the expression of endothelial cell nitric oxide synthase (ecNODS) in conduit and resistance arteries. Aim #3 will determine the effect of HU on ecNOS mRNA content in conduit and resistance arteries. Aim #4 will determine the time course of the reductions in ecNOS activity and mRNA levels. Aim #5 will determine whether exposure to HU reduces vascular flow capacity and the potential for capillary exchange. It is hypothesized that endothelium-dependent vasodilation will be impaired in vessels isolated from rats exposed to HU.