慢性炎性痛模型大鼠诱发焦虑抑郁样情绪行为观察

目的动态观察弗氏完全佐剂(CFA)诱导慢性炎性痛模型大鼠痛情绪的改变情况,探索慢性炎性痛模型大鼠诱导焦虑、抑郁情绪的时间差异性。方法所有实验大鼠随机分为空白对照组和模型对照组,模型对照组于足底注射CFA建立慢性炎性痛模型。动态观察各组大鼠造模前、造模后1,3,7,18和26 d机械缩足阈变化(PWTs);观察造模后28 d旷场实验(OF),29 d高架O迷宫实验(EZM),30 d新奇食物抑制实验(NSF),造模后12,20和31 d大理石掩埋实验(MBT),造模后17,25和35 d糖水偏爱度实验(SPT)中大鼠行为改变情况。结果造模后1 d,模型对照组大鼠PWTs显著降低(P 0. 01),且在整个实验过程中均显著低于空白对照组(P 0. 01)。模型对照组在OF中较空白对照组大鼠的中央区运动距离、中央区停留时间、中央区进入次数显著减少(P 0. 01);在EZM中较空白对照组大鼠的开放臂运动距离,开放臂停留时间,开放臂进入次数显著减少(P 0. 05);在NSF中较空白对照组大鼠摄食潜伏期明显增加(P 0. 05),且食物消耗量无明显差异(P 0. 05);而MBT仅模后31 d,模型对照组较空白对照组大鼠大理石埋藏数量显著增加(P 0. 05); SPT中模后各时间点模型对照组与空白对照组大鼠比较均无明显差异(P 0. 05)。结论 CFA诱发的慢性炎性痛模型大鼠在4周后可出现多种与焦虑样情绪相关的动物行为改变,但在5周内均并未观察到与抑郁样情绪相关的动物行为改变。     

次声作用对大鼠血浆SOD、MDA、NO 水平的影响*

目的:通过观察16 Hz/130 dB次声作用大鼠不同时间其血浆超氧化物歧化酶(SOD)、丙二醛(MDA)、一氧化氮(NO)水平的变化,揭示次声作用对大鼠氧化应激损伤的特点。方法:80只SD大鼠随机分为次声作用1、7、14、21和28 d组及对应的假暴露组,每组8只大鼠。次声暴露组每日定时在次声舱内接受16 Hz/130 dB次声作用2h,连续1、7、14、21和28 d,假暴露组除不施加次声作用外,其在次声舱中放置的时间、次数、采样时间点均和次声暴露组相同。次声暴露后即刻测定大鼠血浆SOD、MDA、NO水平,测得的结果与假暴露组进行比较。结果:与假暴露组相比,大鼠血浆SOD活力在次声作用后显著降低(P<0.05),且随次声作用时间延长,SOD活力逐渐降低;大鼠血浆MDA含量在次声作用后显著升高(P<0.05),且随次声作用时间延长,MDA含量逐渐升高;大鼠血浆NO含量在次声作用7、14 d时显著降低(P<0.05),1、21和28 d时无统计学差异(P>0.05)。结论:次声作用可引起大鼠氧化应激损伤,损伤的程度与次声暴露时间有关。     

模拟失重条件下大鼠比目鱼肌肌梭神经营养因子3表达降低

本研究旨在探讨模拟失重对大鼠比目鱼肌肌梭神经营养因子3(neurotrophin-3,NT-3)表达的影响。采用大鼠尾部悬吊法建立模拟失重动物模型,按体重配对原则随机将大鼠分为5组,即尾悬吊3d组、7d组、14d组、21d组和正常同步对照组。采用免疫组织化学ABC染色法及酶联免疫吸附实验法(ELISA)检测大鼠比目鱼肌肌梭NT-3的表达。结果显示,大鼠比目鱼肌梭外肌中未见到NT-3表达;正常对照组大鼠比目鱼肌肌梭中,核袋1和核袋2纤维NT-3呈现强阳性表达;模拟失重后,梭内肌纤维的NT-3免疫染色反应进行性降低;NT-3的ELISA定量检测结果显示,正常组、尾悬吊3d组、7d组、14d组和21d组大鼠比目鱼肌NT-3的含量分别为(14.23±1.65)、(14.11±1.53)、(13.09±1.47)、(12.45±1.51)和(9.85±1.52)pg/mg。统计比较显示,尾悬吊14d后,大鼠比目鱼肌NT-3的含量较正常对照组明显减少(P<0.05);而尾悬吊21d后,大鼠比目鱼肌NT-3的表达进一步减少(P<0.01)。以上结果表明,模拟失重可致大鼠比目鱼肌肌梭NT-3的表达明显减少,并且随着模拟失重时...     

人参皂苷Rg1对抑郁症大鼠抑郁行为和海马神经元损伤、PKA、PKC的影响

摘要 目的：探讨与分析人参皂苷Rg1对抑郁症大鼠抑郁行为和海马神经元损伤、蛋白激酶A（PKA）与蛋白激酶C（PKC）的影响。方法：抑郁症大鼠48只随机平分为三组-模型组、实验1组、实验2组,每组16只大鼠。实验1组、实验2组每天2次灌胃给药（1 mg/mL、4 mg/mL人参皂苷Rg1）,给药体积为10 mL;模型组以相同方式按体重给予双蒸水。观察与记录鼠抑郁行为和海马神经元损伤、PKA、PKC表达变化情况。结果：实验1组、实验2组治疗第7 d、第14 d的逃避潜伏期都显著低于模型组,实验2组与实验1组相比也显著缩短（P<0.05）。实验1组、实验2组治疗第7 d、第14 d的糖水偏好率高于模型组,实验2组与实验1组相比也显著升高（P<0.05）。实验1组、实验2组治疗第7 d、第14 d的血清5-羟色胺较模型组高,血清皮质酮含量较模型组低,实验2组与实验1组对比也有明显差异（P<0.05）。实验1组、实验2组治疗第7 d、第14 d的海马神经元组织的PKA、PKC蛋白相对表达水平显著低于模型组,实验2组与实验1组相比也显著缩短（P<0.05）。结论：人参皂苷Rg1在抑郁症大鼠的应用能改善抑郁行为,增加糖水偏好率,降低逃避潜伏期,还可提高大鼠的血清5-羟色胺含量,降低血清皮质酮含量,降低海马神经元组织的PKA、PKC蛋白表达水平。     

饮用加银水对模拟失重大鼠肠道微生态及骨钙代谢的影响

目的 :研究饮用加银水对模拟失重大鼠肠道微生态及骨钙代谢的影响。方法 :30只 SD雄性大鼠随机分为地面对照组 ( GC)、模拟失重对照组 ( SC)和模拟失重饮用 0 .2 0 mg/ L 加银水组 ( SS) ,实验期 2 1d。第 7、14和 2 1天用选择性培养基分别对肠球菌、肠杆菌、双歧杆菌、乳杆菌及类杆菌定量测定 ,并测定饲料钙表观吸收率 ;第 2 1天取右侧股骨测骨密度和骨钙含量。结果 :骨密度和骨钙含量 SC组显著低于 GC组 ,SS组也低于 SC组 ;SC组和 GC组比较 ,SC组出现厌氧菌群的减少和需氧菌群的增加及饲料钙表观吸收率的下降 ,且这种变化出现较早 ,SS组和 SC组比较 ,SS组出现以厌氧菌群中 G 菌的减少和需氧菌群G-菌的增加为主的菌群失调及饲料钙表观吸收率的下降 ,且这种变化出现较晚。结论 :饮用 0 .2 0 mg/ L 加银水可以加重模拟失重大鼠肠道微生态的失调和骨钙代谢的紊乱 ,但需要较长的作用时间 ,且其微生态的失调以 G 细菌减少为主的厌氧菌群减少型     

甘麦大枣汤对抑郁模型大鼠海马神经元突触结构及结构蛋白表达的影响*

目的: 观察甘麦大枣汤对抑郁模型大鼠行为学及单胺递质的影响,并从突触结构及结构蛋白MAP-2与GAP-43表达改变探讨其潜在作用机制。方法: 60只SD大鼠随机分为5组:正常对照组、模型组、氟西汀组(10.8 mg/kg)、甘麦大枣汤高、低剂量组(9.72、4.86 g/kg),每组12只。除对照组外,其余各组大鼠均采用慢性不可预见性温和应激(CUMS)建立抑郁模型,并于造模同时给药组灌胃给药,连续21 d。采用糖水消耗实验和旷场测试评价大鼠抑郁样行为,ELISA法检测海马单胺递质5-HT、NE含量,Golgi染色观察神经元突触损伤情况,免疫组化法和Western blot法检测海马突触结构蛋白MAP-2和GAP-43的表达。结果: 与对照组比较,抑郁模型大鼠糖水偏好度及自主活动评分均显著下降(P＜0.01),海马5-HT、NE含量显著下降(P＜0.01),树突棘缺失明显,同时MAP-2和GAP-43表达均显著下调(P＜0.01);甘麦大枣汤干预后,模型大鼠抑郁样行为明显缓解(P＜0.01),5-HT、NE含量显著升高(P＜0.05),树突棘密度、长度及分枝增加,MAP-2和GAP-43表达显著回升(P＜0.01)。结论: 甘麦大枣汤能改善抑郁模型大鼠的抑郁样行为,升高海马单胺递质含量,其作用可能与上调突触结构蛋白、缓解神经元突触损伤有关。     

羊水干细胞治疗维甲酸诱导的大鼠骨质疏松的初步研究

目的:维甲酸(ratinoicacid)诱导雌性大鼠骨质疏松(Ostoporosis,OP)模型,观察并分析羊水干细胞(amniotic fluid-derivedstem cells,AFS)对OP的治疗作用。方法:选取40只S D雌性大鼠,随机分为4组,每组10只。除正常组(A组)外,模型组(B组),一次注入AFS组(C组)和两次注入AFS组(D组)均用维甲酸70 mg/(k g.d)连续灌胃1 4 d,A组用等量灭菌注射用水灌胃。于给药二,三周分别测量各组大鼠血清Ca、Pi、碱性磷酸酶ALP和抗酒石酸酸性磷酸酶TRACP含量,制造模型(简称造模)过程观察动物生活习性体重等变化,实验结束进行股骨骨形态计量学测量,骨薄片病理学观察。结果:造模过程中,大鼠出现少食,竖毛,及体重减轻。B.C组大鼠体重较正常组显著降低(P<0.05)。造模21d后,B组血清Ca2+水平显著升高。模型组骨密度较正常组显著下降(P<0.05),但D组骨密度变化无明显统计学意义。B,C,D组血清ALP,TRACP均明显高于正常组(P<0.05)。骨薄片染色显示模型组骨胶原排列杂乱无序,结构松散,D组有修复迹象。结论:羊水干细胞尾静脉注射可缓解维甲酸诱导的大鼠骨质疏松,且两次次给药的治疗效果好于单次给药。     

创伤后应激障碍对慢性不可预见性应激抑郁模型的影响

目的:观察创伤后应激障碍(PTSD)对慢性不可预见性应激(CUS)抑郁模型的影响。方法:采用足底电击的方法建立大鼠创伤后应激障碍模型。成年雄性S-D大鼠40只随机分为四组(n=10):对照组(C组)、PTSD组、CUS组、PTSD+CUS组(P+C组)。在1、7、14、21天测量大鼠体重,并行糖水偏好和强迫游泳实验,在7、14、21天做条件性恐惧实验。结果:与C组相比,CUS组和P+C组体重增加缓慢,PTSD组体重正常。CUS组于第21天出现糖水消耗比例降低,强迫游泳不动时间增加。P+C组于第14天即出现上述抑郁表现。条件性恐惧实验中,PTSD组与PTSD+CUS组僵直时间显著增加,CUS组无明显变化。结论:创伤后应激障碍的动物更易产生抑郁表现。     

近交系HFJ大鼠的抗肿瘤细胞Walker-256特性

目的检测近交系HFJ大鼠的肿瘤学特性。方法采用大鼠肿瘤细胞Walker-256分别接种HFJ大鼠和Wistar大鼠制作腹水瘤、实体瘤模型,观察两种动物对同一种肿瘤细胞的敏感性及免疫反应差异。结果对于腹水瘤Walker-256接种7d,Wistar大鼠有6只腹水产生为阴性,HFJ大鼠腹水产生均为阳性。继续观察至20d,可见到Wistar大鼠有3只腹水阴性(阳性率9/12,死亡2只,染色体用1只),而HFJ大鼠腹水全部为阴性(阳性率0/12,死亡2只,染色体用1只)。腹水中Walker-256细胞染色体分析,Wistar大鼠和HFJ大鼠众数变化范围均为50～62条,无显著差异。实体瘤接种7d,Wistar大鼠和HFJ大鼠均可触摸到右侧腋下有肿块产生。20d后Wistar大鼠除2只肿块消失外其他均有肿块存在并随时间延长而增大(阳性率13/15);所有HFJ大鼠腋下肿块均变软并逐渐消失(阳性率0/15)。检测各组大鼠的细胞免疫、体液免疫功能,发现正常HFJ大鼠IgM、IgA显著低于Wistar大鼠(P<0.01),IgG差异不显著。荷瘤组HFJ大鼠和Wistar大鼠IgG均高于各自正常对照组,差异极显著(P<0.01)。Wist-ar大鼠腹水瘤阳性组IgG显著低于阴性组和HFJ腹水阳性组(P<0.05),Wistar大鼠实体瘤阳性组也显著低于HFJ实体阳性组(P<0.01)。Wistar大鼠腹水瘤阳性组IgM显著低于阴性组(P<0.05),Wistar大鼠腹水瘤阴性组和HFJ大鼠腹水瘤、实体瘤阳性组IgM均高于各自对照组,且差异显著(P<0.05)。细胞免疫结果显示各组CD4+数量差异不显著;正常HFJ大鼠CD8+显著少于Wistar大鼠(P<0.05),Wistar大鼠腹水瘤和实体瘤阳性组CD8+数量较阴性组和正常对照组均显著减少(P<0.05)。各荷瘤阴性组大鼠CD8+数量均较正常值增加,除Wistar大鼠腹水瘤和HFJ实体瘤阴性组大鼠差异显著(P<0.05)外,其他均不显著;CD4+/CD8+结果与CD8+相反。结论 HFJ大鼠具有抗大鼠肿瘤细胞Walker-256的特性,腹水瘤及实体瘤均不易生长。     

CFA注射致炎性疼痛过程中海马内BDNF的表达及作用研究

目的:探索完全弗氏佐剂(Complete Freund’s Adjuvant,CFA)致炎性疼痛后大鼠海马内脑源性神经营养因子(brain-derived neurotrophic factor,BDNF)表达的变化及其作用。方法:雄性SD大鼠随机分为溶媒对照组和实验组,实验组大鼠左侧足底皮下注射CFA和生理盐水混合溶剂100μL,建立炎性疼痛模型,注射后大鼠分别存活1天、4天、7天、14天(n=20只/组)。在建模前和建模后不同时间点采用Von Frey纤维检测大鼠50%机械缩足阈值(paw withdrawal threshold,PWT)的变化。采用强迫游泳实验和糖水偏好实验检测大鼠抑郁样行为,采用RT-PCR检测不同时间点大鼠海马中BDNF m RNA的水平,采用ELISA和免疫组织化学法检测BDNF的表达变化。结果:足底注射CFA后1天50%PWT下降,持续至14天仍低于基础值。在强迫游泳实验中,注射CFA7天后的大鼠不动时间百分比增加,一直持续到CFA注射后14天。糖水偏好实验中注射CFA后7天组、14天组大鼠表现出对糖水偏好的降低,提示注射CFA后7天大鼠出现抑郁样行为并持续到第14天。在足底注射CFA第7天后BDNF m RNA和BDNF的水平达到高峰,第14天表达下调并基本恢复正常水平。结论:结果提示,足底注射CFA能诱导大鼠产生炎性痛,CFA注射7天后出现抑郁样行为,此时海马内BDNF m RNA和BDNF蛋白水平均上调,可能与足底注射CFA后出现的抑郁样行为的发生密切相关。     

Ultrastructure of ependyma in brain third ventricle of the rats exposed to repeated tail-suspension. Scanning electron microscopical study

By means of scanning electron microscopy the ultrastructure of ependyma was studied in the brain third ventricle of the rats repeatedly exposed to 14-day tail-suspension (TS). Animals were subjected to TS for 30 days, then readapted to horizontal position during 30 days and again, repeatedly subjected to TS for 14 days simultaneously with the rats which were in TS for the first time during 14 days. Repeated TS of rats, inspite of repeated redistribution of body liquid mediums in cranial direction, results in considerably less expressed destructive changes in ultrastructure of ependymocyte cilia, then after primary 14- and 30-day TS, showing much greater cerebrospinal fluid (CSF) outflow from brain ventricles into sagittal venous sinus at postponed for a long time, repeated simulation of weightlessness effects in comparison with CSF outflow at primery one.     

川芎嗪对模拟失重大鼠颈动脉平滑肌Ca2+敏感性的影响

目的：探讨川芎嗪对模拟失重大鼠颈动脉平滑肌收缩蛋白Ca²⁺敏感性的影响及机制。方法：21只雌性SD大鼠分为对照组（CON）、模拟失重组（TS）、模拟失重+川芎嗪灌饲组（LTZ）（n=7）。4周后测定大鼠颈动脉收缩性、收缩蛋白Ca²⁺敏感性及肌球蛋白轻链激酶抑制剂ML-7对以上指标的影响。结果：TS组苯肾上腺素（PHE）收缩力比CON组高25.14%（P<0.01）,LTZ组较TS组低13.46%（P<0.01）,较CON组高8.30%;ML-7可使CON、TS、LTZ组PHE收缩力分别降低8.84%、16.24%（P<0.01）和3.40%;TS组KCl收缩力比CON组高40.46%（P<0.01）,LTZ组较TS组低18.80%,较CON组高14.05%;ML-7可使CON、TS、LTZ组KCl收缩力分别降低21.97%（P<0.05）、21.88%（P<0.01）和10.84%;TS组pD2[Ca²⁺]比CON组高10.03%（P<0.01）,LTZ组较TS组低7.01%（P<0.01）,较CON组高2.32%;ML-7可使CON、TS、LTZ组pD2[Ca²⁺]分别降低2.42%、7.43%（P<0.01）和2.51%。结论：模拟失重大鼠颈动脉收缩增强可能是由动脉平滑肌收缩蛋白Ca²⁺敏感性增强所导致的。川芎嗪可改善模拟失重大鼠颈动脉的收缩功能,其机制可能与抑制血管平滑肌肌球蛋白轻链激酶继而降低Ca²⁺敏感性有关。     

Short-term simulated weightlessness enhances response of L-type calcium channel to angiotensin II in cerebral vascular smooth muscle cells in rats

Some studies suggest that the calcium channels and rennin-angiotensin system (RAS) play pivotal roles in the region-specific vascular adaptation due to simulated weightlessness. This study was designed to clarify if angiotensin II (Ang II) was involved in the adaptational change of the L-type calcium channel (Ca(L)) in the cerebral arterial vascular smooth muscle cells (VSMCs) under simulated weightlessness. Tail suspension (SUS) for 3 d was used to simulate immediate early cardiovascular changes to weightlessness. Then VSMCs in cerebral basilar artery were enzymatically isolated using papain, and Ca(L) current (barium instead of calcium as current carrier) in VSMCs was measured by whole-cell patch-clamp techniques. The results showed that 3-day simulated weightlessness significantly increased current density of Ca(L). However, I-V relationships of normalized peak current densities and steady-state activation curves of Ca(L) were not affected by simulated weightlessness. Although Ang II significantly increased current densities of Ca(L) in both SUS and control rats, the increase of Ca(L) current density in SUS rats was much more than that in control rats. These results suggest that 3-day simulated weightlessness induces the adaptational change of Ca(L) in cerebral VSMCs including increased response to Ang II, indicating that Ang II may play an important role in the adaptational change of cerebral arteries under microgravity.     

Influences of chemical sympathectomy and simulated weightlessness on male and female rats.

Maximum oxygen consumption (VO2max) has been shown to be reduced after periods of simulated weightlessness. To assess the role of the sympathetic nervous system in these reductions, Sprague-Dawley rats were either chemically sympathectomized (SYMX) or injected with saline (SHAM) and assigned to head-down suspension (HDS), horizontal restraint with the hindlimbs weight bearing (HWB), or cage-control (CC) conditions. VO2max, run time (RT), and mechanical efficiency (ME) were measured before suspension and on days 7 and 14. Male and female SHAM HDS groups exhibited reduced measures of VO2max (12-13%) after 7 and 14 days, and this decrease was attenuated in the SYMX and HWB rats. HDS resulted in a significant reduction in RT (9-15%) in both the male and female rats, and ME was significantly reduced after HDS in male and female SYMX and male SHAM rats (23-33%) but not in the female SHAM rats. Lesser reductions in ME were observed in the HWB rats. HDS and HWB were associated with lower body, fat-free, and fat masses, which were similar in male and female rats as well as for the SHAM and SYMX conditions. In a related HDS experiment with normal rats, plasma norepinephrine and epinephrine were increased by 53 and 42% after 7 days, but only epinephrine returned to baseline after 14 days. It was concluded that chemical sympathectomy and/or a weight-bearing stimulus will attenuate the loss in VO2max associated with simulated weightlessness in rats despite similar changes in body mass and composition. The mechanism(s) remains unclear at this time.     

Modulation of {beta}-adrenoceptor signaling in the hearts of 4-wk simulated weightlessness rats.

The modulation of beta-adrenoceptor signaling in the hearts of hindlimb unweighting (HU) simulated weightlessness rats has not been reported. In the present study, we adopted the rat tail suspension for 4 wk to simulate weightlessness; then the effects of simulated microgravity on beta-adrenoceptor signaling were studied. Mean arterial blood pressure (ABP), left ventricular pressure (LVP), systolic function (+dP/dtmax), and diastolic function (-dP/dtmax) were monitored in the course of the in vivo experiment. Single rat ventricular myocyte was obtained by the enzymatic dissociation method. Hemodynamics, myocyte contraction, and cAMP production in response to beta-adrenoceptor stimulation with isoproterenol or adenylyl cyclase stimulation with forskolin were measured, and Gs protein was also determined. Compared with the control group, no significant changes were found in heart weight, body weight and ABP, while LVP and +/-dP/dtmax were significantly reduced. The ABP decrease, LVP increase, and +/-dP/dtmax in response to isoproterenol administration were significantly attenuated in the HU group. The effects of isoproterenol on electrically induced single-cell contraction and cAMP production in myocytes of ventricles in the HU rats were significantly attenuated. The biologically active isoform, Gsalpha (45 kDa) in the heart, was unchanged. Both the increased electrically induced contraction and cAMP production in response to forskolin were also significantly attenuated in the simulated weightlessness rats. Above results indicated that impaired function of adenylyl cyclase causes beta-adrenoceptor desensitization, which may be partly responsible for the depression of cardiac function.     

Effects of microgravity on organ development of the neonatal rat.

We analyzed various organs in the same rats to study effects of gravitational condition on organ development of the neonatal rat in this study. Eight-day old and 14-day old Sprague-Dawley rats were flown for 16 days on the Space Shuttle Columbia (April 17-May 3, 1998). The organs were weighed and the ratio of the organ weight to the body weight (organ weight ratio; OBR) was calculated. Tissues were analyzed using anatomical, immunohistochemical and molecular biological technique. Six animals of the 8-day old group were reared on the ground for 30 more days after landing. The differences between flight and control rats in 8-day group were drastic. The lung, heart, kidney and adrenal glands in flight rats were significantly larger than that of control rats in OBR comparison. However, only the lung and kidney were still larger after 30 more days on ground. The kidney in flight rats performed pelvis expansion with down-regulation of aquaporin-2 expression confirmed by immunohistochemistry. The thymus, spleen, mesentery and pancreas were smaller in OBR. But the thymus in flight rats was heavier after 30 more days. The organs in flight rats which had no differences in OBR showed normal characteristics in histological analysis. We also found that the number of unmyelinated fibers of the aortic nerve in flight rats of 8-day group was smaller than that in control rats. In flight rats of the 14-day group, only the kidney was heavier and the ovary was lighter as compared to the controls. These results implied the second week of life was important for development during spaceflight. And the sensitivity and the critical period on neonatal development under microgravity might differ in each organ.     

Cortico-adrenal function under simulated weightlessness during gestation in the rat--effects on fetal development

To examine the effects of simulated weightlessness on cortico-adrenal function and on fetal development, we suspended pregnant rats for 20 days. The levels of adrenal and plasma corticosterone were examined in mothers and in fetuses. The animal control group was kept single in standard cages. Growth of the suspended animals was repressed for the first 8 days of the experiment, but thereafter it increased greatly, as did the daily food intake. By the 18th day of the experiment, the body masses and food intake of the two groups were equal. No modification in circulating corticosterone was found. It appears that there is no stress in pregnant rats submitted to simulated weightlessness.     

Effect of simulated weightlessness on pressure-volume relationships of femoral veins in vivo of New-Zealand rabbits

Objectives: To observe the change of pressure-volume relationships of femoral veins of rabbits after simulated weightlessness. Methods: Head-Down Tilt(HDT) -20 degrees rabbit model was used to simulate weightlessness .24 healthy male New-Zealand Rabbits were randomly divided into 21d HDT group, 10d HDT group and control group, with 8 in each. The pressure-volume relationships of rabbits femoral veins were measured. Result: The femoral vein P-V relationship curves of HDT groups were shifted to larger volume change ratio than that of control group. The P-V relationship curve of the 21d HDT group was shifted more obviously than that of HDT-10d. B1 and B2 in quadratic equations of 21d HDT group were significantly higher than these value of 10d HDT group and control group during expansion (inflow) and collapse (outflow) (P<0.01). Conclusions: The femoral venous compliance increased after weightlessness simulation and the femoral venous compliance of 21d-HDT increased more obviously than that of 10d-HDT.