浸水运动对小鼠主动脉弹性储器作用适应性改变的研究

Water Immersion Exercises Induced Adaptation of Windkessel Properties in Aorta Wall

目的全身浸水静水压对胸腔及四肢的压力是模拟微重力环境下体液重新分布的实验模型。观察动物离体主动脉被动牵拉后回缩并测量在体动脉压波形的降中峡,可了解主动脉作为弹性储器血管的的适应性改变。方法昆明小鼠分浸水组(n=20)及对照组(n=10)。浸水运动20 min/天持续1周并实施左颈总动脉插管采集压力波,测量并统计主动脉波的叩击波积分以推算每搏量;离体实验取小鼠主动脉血管环于37℃任氏液中,牵拉至1 g为初始负荷,随后间隔5 min牵拉1 g共计10次,计算小鼠主动脉标本低负荷(2 g)及高负荷(11 g)的应力松弛时程及肌源性自主收缩,比较组间显著性差异。另用0.05%Ca^(2+)拮抗剂(Nitrendipine)预处理标本后提高任氏液中Ca^(2+)浓度至2.50 m M/m L,观察预处理后肌原性舒缩改变,了解Ca^(2+)浓度影响。结果浸水组动脉压力波形变化明显,平均动脉压略有上升(9.14±0.63 k Pa,8.40±0.97 k Pa),左心室搏出量增长显著(13.96±0.12 L/min,5.14±0.69 L/min)。浸水组主动脉血管环肌原性自主收缩显著减少,应力松弛时程缩短。0.05%Nitrendipine预处理对应力松弛时程无显著改变,而对肌原性自主舒缩影响显著,提示其受Ca^(2+)跨膜流动影响。结论全身浸水的体液重分布对提高左心室快速射血期与等容舒张期功能具有一定意义,提示微重力环境对提高主动脉弹性储器功能具有积极意义,细胞膜Ca^(2+)通透性参与了这种改善作用。

Objective Body immersion induced hydrostatic pressure overloading on thoracic cavity and limbs is a simulation model for microgravity environment. The investigations of stretching aorta intact smooth muscle in vitro and hemodynamie evaluations the dicrotic notch can determine windkessel adaptation changes. Methods Kunming mice were divided into immersion exercise group （n =20） and control group （n = 10）. Mice were body immersion 20 min/day in warm water for 1 week. Left common carotid artery cannulation was for collecting arterial blood pressure. Data analyzed by biological signal acquisition system. Calculi of percussion wave were calculated with integral mode to determine left ventricle stroke volume. In vitro aortic prepared to vascular rings then incubated in ringer＇ s solution, loading preparation to 1 g as the initial load. Stretching preparations 10 steps with the interval of 5 min which gradually increasing lg in each step. Calculate the stress relaxation duration and myogenic spontaneous contraction. In a separated preparation, after pretreated with O. 05% Nitrendipine adjusted the Ca^2＋ to 2. 50 mM/ml, investigated myogenic contraction changes by Ca^2＋. Results The immersion mice carotid arterial pressure waveform have significantly changed. Mean arterial pressure were slightly increased in immersion mice but not significantly （ immersion 9. 14 ＋ 0. 63 kP, control 8.40 ＋ 0. 97 kPa, n = 10）. Left ventricle stroke volume increased significantly （ immersion 13.96 ± 0. 12 L/min, control 5.14 ±0. 69 L/min, n = 10）. In vitro immersion mice preparations have less traction, stress relaxation ing. Pretreatment of 0. 05% myogemc spontaneous con period were shorten- Nitrendipine induced more myogenic spontaneous contraction that is reveal Ca^2＋ conductance involved in myogenic spontaneous contraction. Conclusions Immersion exercise improved left ventricle functions in rapid ejection and isodiastolic period, suggested aorta compliance can improved in microgravity, this also influenced by membrane permeability of Ca^2＋.