反复下体负压致脑缺血对大鼠脑组织离子含量ATP酶活性？…

为阐明多次发生了＋Ｇｚ致意识丧失对脑的影响及其机制，观察了反复下体负压（ＬＢＮＰ）致脑缺血对大鼠脑组织离子含量，ＡＴＰ酶活性及神经元形态的影响，雄性ＳＤ大鼠３０只，随机分为３组，将动物麻醉后置于－４．０ｋＰａ的下体负压舱内（下降速率为０．６７ｋＰａ／ｓ），至脑电波消失２ｍｉｎ后恢复常压。分别于一次和三次ＬＢＮＰ作用后１ｈ测定脑组织Ｎａ＾＋－Ｋ＾＋－ＡＴＰ酶活性，Ｋ＾＋，Ｎａ＾＋及水含量等。结果表明     

反复下体负压致意识丧失对大鼠血脑屏障通透性的影响

为阐明多次发生＋Ｇｚ致意识丧失对脑的影响及其机制，观察了反复下体负压（ＬＢＮＰ）致意识丧失对大鼠血脑屏障（ＢＢＢ）通透性的影响。雄性ＳＤ大鼠，麻醉后置于－４．０ｋＰａ的下体负压舱内，至脑电波消失２ｍｉｎ后恢复常压。分别于一次和三次ＬＢＮＰ作用后１ｈ利用硝酸镧示踪法观察ＢＢＢ通透性的变化。一次ＬＢＮＰ致意识丧失组大鼠脑皮层组织变化不明显；三次ＬＢＮＰ致意识丧失组大鼠脑皮层组织中大部分毛细血管内皮细胞     

坐位下体负压对人体脑功能影响的实验研究

 目的探讨坐位下体负压(Lower body negative pressure,LBNP)暴露时对人体脑功能的影响。方法 15例健康青年男性被试者在坐位LBNP-4.00 kPa(-30 mmHg)、-6.67 kPa(-50 mmHg)的条件下,分别测试暴露前、暴露时和卸压后的脑事件相关电位(Event related potential,ERP)P300、反应时(Reaction tinle,RT)及跟踪误差(Trackng error,TrE)等工效学指标,并记录主观症状。结果在-4.00 kPa LBNP作用时,P300波幅、潜时、反应时、跟踪误差与负压前对照差异无显著性意义(P＞0.05)。在-6.67 kPa LBNP作用时,P300波幅降低(P＜0.01),P300潜时延长(P＜0.01),反应时延长(P＜0.05),跟踪误差增大(P＜0.05)。主观症状随着负压值的增大,症状数量增多,程度加重。结论 坐位下体负压造成血液在下肢积聚,引起大脑供血量减少,从而引起大脑对外界的反应减慢,脑认知工效下降。     

海水浸泡对大鼠晶状体Na+,K+-ATP酶表达的影响

目的研究大鼠晶状体海水浸泡伤后Na^＋，K^＋浓度和Na^＋，K^＋-ATP酶在mRNA水平的表达与形态学损伤之间的关系。方法用逆转录聚合酶链式反应法测定大鼠晶状体Na^＋，K^＋-ATP酶α亚单位在mRNA水平的表达状况，并与Na^＋，K^＋浓度和超微结构的变化进行对比分析。结果海水浸泡大鼠晶状体Na^＋，K^＋-ATP酶的α1，α2，α3亚单位mRNA水平的表达首先代偿性增高，随后呈失代偿性降低，并随时间的延长而逐渐降低。海水浸泡30min缝合伤口观察1周组的α1及α2亚单位的表达高于对照组，α3亚单位的表达基本恢复正常。结论在晶状体海水浸泡伤的病变过程中，Na^＋，K^＋-ATP酶亚单位活性的表达有不同变化。     

Alterations in antioxidant status, protein concentration, acetylcholinesterase, Na+, K+-ATPase, and Mg2+-ATPase activities in rat brain after forced swimming

The aim of this study was to investigate whether exercise stress (short [2 h] or prolonged [5 h] forced swimming in rats) could modulate brain total antioxidant status (TAS), tissue protein concentration, and the activities of acetylcholinesterase (AChE), Na +, K +-ATPase, and Mg 2+-ATPase. Protein concentration, TAS and enzyme activities in homogenized rat brain were determined spectrophotometrically. Protein concentration was decreased by 15 % (p < 0.01) and by 30 % (p < 0.001) after 2 h and 5 h of forced swimming, respectively. TAS was decreased by 20 - 25 % after 2 h or 5 h of exercise. AChE was inhibited by 30 % (p < 0.001) and 45 % (p < 0.001) after 2 h and 5 h of forced swimming, respectively. In contrast, Na +, K +-ATPase and Mg 2+-ATPase were stimulated by 80 % (p < 0.001) and 40 % (p < 0.001), respectively, after 2 h of swimming and by 100 % (p < 0.001) and 60 % (p < 0.001), respectively, after 5 h of exercise. Control values in nontreated rats were unaltered (p > 0.05). In conclusion, short or prolonged forced swimming induces oxidative stress in rats, probably resulting in a reduction in brain protein concentration and AChE activity. In addition, a Na +, K +-ATPase and Mg 2+-ATPase activation was observed under the above mentioned experimental conditions. This stress condition may modulate brain intracellular Mg 2+ concentration, neural excitability, metabolic energy production, and neurotransmission.     

Vasodepressor syncope induced by lower body negative pressure: possible relevance to +Gz-stress training--a case report

We present a case report of vasodepressor syncope with brief sinus pause in a 26-year-old male subject following a graded lower body negative pressure (LBNP) challenge culminating at -70 mm Hg. Cessation of the LBNP protocol resulted in the return of heart rate and blood pressure activity to pre-challenge levels. Sinus arrest during central hypovolemic stress has been noted in the literature. Its potential in rare cases during exposure to high levels of LBNP should be noted as increasing numbers of investigators utilize presyncopal LBNP testing to assess the orthostatic responses of pilots and astronauts.     

模拟高强度军事训练对大鼠肾组织Na+,K+-ATP酶活性的影响

目的:探讨模拟高强度军事训练对大鼠肾组织Na+,K+-ATP酶活性的影响.方法:①一次性力竭运动:大鼠随机分对照组(A组)、一次性力竭运动组(B组).B组模拟军事训练行一次性力竭跑台运动,检测运动结束即刻(B1组)及24h后(B2组)尿液指标及肾组织Na+,K+-ATP酶活性.②递增负荷跑台运动:大鼠随机分对照组(C组)、递增负荷跑台运动组(D组).D组模拟军事训练行递增负荷跑台运动,检测4周末(C1组、D1组)和8周末(C2组、D2组)尿液指标及肾组织Na+,K+-ATP酶活性.结果:①一次性力竭运动结束即刻,B1组尿蛋白、尿N-乙酰-β-D-葡萄糖苷酶(NAG酶)较A组显著升高(P＜0.05),肾组织Na+,K+-ATP酶活性显著降低(P＜0.05),24h后有所恢复但仍低于A组(P＜0.05).②递增负荷跑台运动4周末D1组尿蛋白、尿NAG酶、肾组织Na+,K+-ATP酶活性均较C1组显著升高(P＜0.05);8周末D2组尿蛋白、尿NAG酶较C2组显著升高,肾组织Na+,K+-ATP酶活性显著降低(P＜0.05),且与尿NAG酶排泄呈负相关.结论:模拟高强度军事训练可引起大鼠肾组织Na+,K+-ATP酶活性的不同改变.     

快速下体负压模拟 Gz致意识丧失的大鼠模型

目的动物离心机的特殊操作条件，限制了生理监测技术的应用。因此，仅依靠单一的动物离心机模型不能满足多层次系统研究的需要，必须建立多种模拟＋Gz致意识丧失（G－LOC）的动物模型。方法应用快速下体负压（LBNP）模拟＋Gz引起的意识丧失。结果发现麻醉大鼠分别在-2.67（－20mmHg）、-4.00（－30mmHg）及-5．33（－40mmHg）kPa的LBNP作用下，眼水平动脉血压迅速降低，脑电波消失的时间分别为41．33±11．48、30．67±3．88及25．67±30.45s,此时心率明显变慢（P＜0．05）。恢复常压后眼水平动脉血压、心率及脑电图即迅速恢复正常，个别出现心律失常、心率减慢。结论本大鼠模型损伤小，可进行反复缺血再灌流和模拟＋Gz引起的血液转移，为深入研究G－LOC的机理提供了一种有用的模型。     

The effect of basketball training on the players' erythrocyte membrane acetylcholinesterase, (Na+,K+)-ATPase and Mg2+-ATPase activities

The aim of this study was to investigate whether the activities of erythrocyte membrane acetylcholinesterase (AChE), (Na (+),K (+))-ATPase and Mg (2+)-ATPase are modulated by a basketball training. Blood was obtained from 10 basketball players pre- and postexercise. Total antioxidant status (TAS), lactate and pyruvate concentrations were determined with kits, while the enzyme activities were determined spectrophotometrically. Post-training blood lactate and pyruvate concentrations as well as AChE (2.90 +/- 0.05 vs. 3.98 +/- 0.09 Delta OD/min . mg protein, p < 0.01) and Na (+),K (+)-ATPase (0.58 +/- 0.04 vs. 1.27 +/- 0.12 micromol Pi/h . mg protein, p < 0.001) activities were remarkably increased, whereas TAS was significantly decreased. Mg (2+)-ATPase activity remained unaltered at the end of the training. In conclusion, the stimulation of AChE and Na (+),K (+)-ATPase by the training may be due to the rise of blood catecholamine oxidation contributing to TAS decrease and/or the increase of serotonin levels. This stress condition may modulate cholinergic and catecholaminergic/serotoninergic functions in players.     

下体负压对人计算能力的影响

目的 探讨下体负压对计算能力的影响。方法 采用坐位下体负压舱对6名男性健康受试者施加40mm Hg的负压，使用威能智力计算训练模块，在屏幕上显示2位数字连加，减4项算式，计正确次数和错误次数，以测试计算能力，于施压前和施压第3分钟作1min计算能力的测试，并且同时记录血压，心率和心输出量。结果 暴露于下体负压负荷40mmHg时，每分钟计算正确次数减少，有显著性差异（P＜0．05），而每分钟计算错误次数地显著差异（P＞0．05）。结论 在下体次数减少，有显著性差异（P＜0．05），而每分钟计算错误次数无显著差异（P＞0．05）。结论 在下体负压负荷作用下计算能力下降，表现为正确计算次数减少，提示下体负压负荷时，脑的高级功能下降。     

下体负压裤的研制与应用

下体负压 (lower body negativepressure,L BNP)是模拟重力 -惯性力场对人体循环功能影响的有效方法之一 ,在航空航天医学教学、科研及医疗等工作中已得到广泛应用 [1 - 4 ] 。国内外已研制成功卧位和坐位下体负压舱 [5 - 6 ] ,其性能大同小异。但下体负压舱体积大、笨重 ,不便于飞行员 /宇航员的使用及执行任务。因此 ,研制一种轻便、有效、安全且可普及推广的下体负压装置很有必要。国外曾报道在航天飞行中应用下体负压裤(Chibis裤 )以对抗失重的影响 [7] 。近期我们研制出一种下体负压裤 ,其结构及其应用情况如下。一、设计与制作1.设…     

下体负压晕厥前症状时脑功能指标的变化特征

目的　探讨下体负压晕厥前症状 ( PSS)时头部血压 ( HBP)、颞动脉血流 ( TBF)、脑电 β2功率指数 ( PIβ2 )的变化特征 ,为飞行员加速度性晕厥的医学鉴定提供试验依据。　方法　用下体负压方法 ( L BNP)诱发 PSS,观察 HBP、TBF及 PIβ2 的变化特征。　结果　出现 PSS时 ,HBP由 ( 10 .0±0 .6 ) k Pa突降至 ( 3.6± 0 .5 ) k Pa,PIβ2 ( Oz电极 )由 ( 39.3± 8.4) %突降至 ( 2 3.2± 5 .2 ) % ,并与 HBP同步下降 (相关系数 t检验 P<0 .0 5 ) ,TBF近似中断。　结论　 HBP是反映 PSS的稳定指标 ;PIβ2 在一定范围内直观反映 PSS期间的脑功能状态变化 ,但须参考 HBP;TBF对判断 PSS的发生有参考价值。     

高+Gz重复暴露对大鼠脑组织胶质纤维酸性蛋白表达的影响

目的观察高＋Gz重复暴露后脑组织星形胶质细胞中胶质纤维酸性蛋白（GFAP）表达的变化。方法SD大鼠30只，随机分为对照组和＋10G；暴露组。＋G2暴露组的大鼠暴露于＋10Gz／45S，共暴露5次，中间间隔5min。分别于＋Gz暴露后不同时间灌注取脑，免疫组织化学染色观察脑GFAP的表达情况。结果＋Gz暴露后1d、2d，顶叶皮层、海马GFAP阳性细胞数较对照组均显著增多（P〈0．05），以弱阳性细小型为主；暴露后4d、6d，顶叶皮层、海马GFAP阳性细胞数较对照组进一步增多（P〈0．01），以中等阳性细胞为主，肥大的GFAP增多。结论重复暴露＋10Gz／45s可引起大鼠顶叶皮层、海马GFAP表达显著增加。     

Effect of lower body negative pressure against orthostatic intolerance induced by 21 days head-down tilt bed rest

BACKGROUND: Exposure to actual or simulated weightlessness is known to induce orthostatic intolerance in humans. Many different methods have been suggested to counteract orthostatic hypotension. The repetitive or prolonged application of lower body negative pressure (LBNP) has shown beneficial effects to counter orthostatic intolerance, but devoting so much time to countermeasures is not compatible with space mission objectives or costs. The purpose of the present study was to assess the effects of brief LBNP sessions against orthostatic intolerance during a 21-d head-down tilt (HDT) bed rest. METHODS: There were 12 healthy male volunteers who were exposed to -6 degrees HDT bed rest for 21 d. Six subjects received -30 mm Hg LBNP sessions for 1 h x d(-1) from day 15 to day 21 of the HDT, and six others served as control. Orthostatic tolerance was assessed by means of standard tilt test. RESULTS: Before HDT, all the subjects in the two groups completed the tilt tests. After 21 d of HDT, five subjects of the control group and one subject of the LBNP group could not complete the tilt test due to presyncopal or syncopal symptoms. The mean upright time in the control group 13.0 +/- 4.0 min) was significantly shorter (p < 0.05) than that in the LBNP group (19.0 +/- 2.2 min). Body weight decreased significantly in the control group during HDT, while increasing significantly on day 21 of HDT in the LBNP group. Urine volume increased on days 15-21 of HDT in the control group, but remained unchanged throughout HDT in the LBNP group. A significant decrease in cardiac output and cardiac index, and a significant increase in total peripheral resistance, pre-ejection period, plasma renin activity, aldosterone, and prostaglandin 12 were observed during HDT in both groups. There were no significant differences in these parameters between the two groups. CONCLUSIONS: Brief daily LBNP sessions were effective in preventing orthostatic intolerance induced by 21 d HDT bed rest. However, it did not improve cardiac pump and systolic functions and did not preserve volume regulating hormones.     

Aerobic fitness in women and responses to lower body negative pressure

High aerobic fitness may be associated with impaired responsiveness to orthostatic challenge. This could be detrimental to astronauts returning from spaceflight. Thus, we examined the cardiovascular responses of a group of 45 healthy women to graded lower body negative pressure (LBNP) through 5 min at -50 mm Hg or until they become presyncopal. The ages (range = 23-43 years, mean = 30.4) and peak aerobic capacities (range = 23.0-55.3 ml.kg-1.min-1, mean = 37.8) of these subjects paralleled those of the women astronauts. We monitored heart rate, stroke volume, cardiac output, Heather index of contractility, arterial pressure, peripheral resistance, change in calf circumference, and thoracic impedance (ZO)--a measure of fluid in the chest. The women in this study exhibited the same response pattern to LBNP as previously reported for male subjects. VO2peak of the six subjects who became presyncopal was not different from VO2peak of the tolerant subjects. At rest, only systolic and mean arterial pressures were significantly correlated with VO2peak. Percent changes in calf circumference (i.e. fluid accumulation in the legs) at -30 and -40 mm Hg were the only responses to LBNP significantly related to VO2peak. The greater pooling of blood in the legs during LBNP by women with higher aerobic fitness, and lower percent body fat may be related to more muscle tissue and vasculature in the legs of the more fit subjects. These data indicated that orthostatic tolerance is not related to aerobic capacity in women, and orthostatic tolerance need not be a concern to aerobically fit women astronauts.     

睫状体Na+-K+-ATP酶和碳酸酐酶活性变化与外伤性低眼压的关系

目的研究外伤性前部增生性玻璃体视网膜病变(aPVR)睫状体Na^ -K^ -ATP酶和碳酸酐酶活性变化,进一步深入探讨外伤性aPVR导致慢性低眼压的机制。方法制作外伤性aPVR导致慢性低眼压兔眼模型,分别于伤后2、4、8、16周测量眼压后取眼球,部分睫状体做普通病理切片,HE染色观察,部分睫状体做Na^ -K^ -ATP酶活性测定和碳酸酐酶组织化学观察。结果伤后实验组Na^ -K^ -ATP酶活性下降,而对照组变化不很明显,两组间比较有显著性差异;实验眼睫状体上皮碳酸酐酶部分区域活性接近正常水平,而上皮破坏区域,酶活性较低。结论外伤性aPVR睫状体Na^ -K^ -ATP酶和碳酸酐酶活性降低是导致房水分泌减少及慢性低眼压的一个重要原因。     

Effects of gender on the autonomic modulation of the cardiovascular responses to lower body negative pressure

BACKGROUND: The cardiovascular responses to submaximal lower body negative pressure (LBNP) appear to differ between genders, but the underlying mechanisms are uncertain. HYPOTHESIS: These differences are due to differences in the autonomic modulation of the cardiovascular system. METHODS: There were 14 women and 13 men who underwent LBNP to -50 mmHg in 10 mmHg increments of 6 min each. Heart rate (HR), stroke volume (SV), BP, forearm blood flow and R-R interval data were acquired. Spectral analysis of the R-R interval data was used to assess autonomic modulation with the low frequency component (LF) set at 0.04 to 0.15 Hz and the high frequency component (HF) at 0.15 to 0.4 Hz. RESULTS: The responses to LBNP to -40 mmHg did not differ between groups. LBNP of -50 mmHg evoked greater HR increases in the women than the men (7.2 +/- 1.0 vs. 3.8 +/- 1.1 bpm; p < 0.05), while SV, cardiac output and total peripheral conductance decreased more (-15 +/- 2 vs. -8 +/- 2 ml x beat(-1); -0.668 +/- 0.131 vs. -0.1778 +/- 0.124 L x min(-1); -0.009 +/- 0.002 vs. -0.004 +/- 0.001 units; p < 0.05). Normalized HF, an indicator of the vagal influence on HR variability, declined below rest at -40 mmHg while the LF/HF ratio, an indicator of sympathetic neural modulation of HR variability, increased above rest at -40 mmHg. These responses did not differ significantly between groups. CONCLUSIONS: These results suggest that gender differences in the cardiovascular responses to LBNP are not due to gross differences in modulation of the autonomic nervous systems.     

下体负压训练提高歼击机飞行员加速度耐力二例

一、临床资料例1,男性,28岁,歼-7飞行员,飞行时间600 h,因改装体检入院.改装体检各项检查均正常.离心机检查:3.0 G持续10 s勉强通过,自觉周边灯消失;4.25 G持续6 s时耳水平脉搏消失,并出现G-LOC.患者本人强烈希望能改装合格.     

脑复合剂对脑损伤大鼠Na+-K+-ATP酶、Ca2+-ATP酶活性及Ca2+调控的影响

目的 观察刨伤性脑损伤(traumatic brain injury,TBI)大鼠脑组织匀浆及线粒体Na+-K+-ATP酶、Ca2+-ATP酶活性、神经细胞内游离Ca2+浓度及脑组织钙调蛋白(CaM)表达的动态变化,探讨脑复合剂脑保护作用的分子生物学机制.方法 建立大鼠TBI模型,分别设立假手术组、TBI组及中药治疗组.中药治疗组给予脑复合剂10 g·kg-1·d-1,假手术组及TBI组给予同等剂量等渗盐水,2次/d,连续7 d.分别于TBI后24 h、72 h、1周等3个时相点处死大鼠,动态定量分析各组大鼠脑组织匀浆及线粒体Na+-K+-ATP酶、Ca2+-ATP酶活性、神经细胞内游离Ca2+浓度及脑组织CaM表达的变化.结果 TBI组各时相点大鼠脑组织匀浆及线粒体Na+-K+-ATP酶、Ca2+-ATP酶活性均明显降低,于TBI后72 h后逐渐恢复,1周时仍明显低于假手术组.中药治疗组大鼠脑组织Na+-K+-ATP酶、Ca2+-ATP酶活性显著增加(P＜0.05);TBI组各时相大鼠脑组织神经细胞内游离Ca2+浓度及脑组织CaM表达均有不同程度增高,于伤后24 h达高峰,持续至72 h仍高于假手术组.而中药治疗组各时相大鼠神经细胞内游离Ca2+浓度及脑组织CaM表达明显低于TBI组(P＜0.05).结论 脑复合剂的脑保护作用可能与增加脑组织Na+-K+-ATP酶、Ca2+-ATP酶的活性,从而减轻TBI后脑细胞的能量代谢障碍,降低神经细胞内游离Ca2+浓度及脑组织CaM表达,减轻Ca2+超载所导致的继发性脑损伤有关.