低氧性肺动脉高压大鼠红细胞的变形性,膜流动性及外形变化

为探讨红细胞变形性变化在低氧性肺动脉高压形成中的作用及低氧时红细胞变形性变化机制，本文观察了低氧1、3、5周大鼠红细胞的变形性、膜流动性、红细胞形态、红细胞平均体积（MCV）及红细胞平均血红蛋白浓度（MCHC）变化。结果：（1）低氧1周红细胞变形性即明显下降（即红细胞滤过指数FI增高），低氧时间越长红细胞变形性下降越明显；且与肺动脉压、右心室压升高及右心室肥厚呈负相关。（2）低氧3周及5周大鼠异常形态红细胞数明显增多。（3）低氧5周大鼠红细胞膜流动性明显下降。提示：低氧大鼠红细胞形态异常及红细胞膜流动性下降可使红细胞变形性下降。红细胞变形性下降可能在低氧性肺动脉高压及右室肥厚的发生及发展中起一定的作用。     

模拟高原不同时间缺氧暴露对大鼠红细胞结构与功能的影响

目的:初步探讨模拟高原不同时间缺氧暴露对大鼠红细胞结构与功能的影响及机制。方法:40只雄性SD大鼠随机分成5组(每组8只):常氧组、缺氧1周组、缺氧2周组、缺氧3周组和缺氧4周组。各缺氧组大鼠置于模拟海拔5 800 m的低压舱内,连续暴露相应时间后,采集全血,测定血常规、红细胞变形指数和红细胞渗透脆性,绘制血红蛋白氧解离曲线,分析计算红细胞凋亡率,观察骨髓切片病理学变化。结果:与常氧组相比,各缺氧组红细胞计数、血红蛋白含量、红细胞平均体积、红细胞平均血红蛋白含量和磷脂酰丝氨酸外翻率均显著增加(P0.01),血红蛋白氧饱和度为50%时的氧分压显著增大(P0.05),骨髓红系增生增加,红细胞变形指数及渗透脆性显著降低(P0.01),血红蛋白氧离曲线右移。结论:在模拟高原缺氧初期,外周血中红细胞的结构与功能发生代偿性改变以利于高原习服;但是,随着缺氧时间的延长,血管内滞留过多的异常红细胞容易导致血栓形成及微循环障碍,并加重机体的组织细胞缺氧。     

低氧对巨核细胞生成影响的研究进展

低氧刺激骨髓红细胞（ＲＢＣ）和抑制巨核细胞（Ｍｋ）的生成。低氧抑制骨髓巨核细胞生成的解释机制包括：随机模型，定数论模型、自身调节假说及干细胞竞争假说等。     

氯化铵裂解法与非裂解法提取人脂肪干细胞生物学特性的差异

文题释义： 氯化铵红细胞裂解液：含有氯化铵成分的红细胞裂解液,此种裂解液被广泛应用于骨髓干细胞及脂肪干细胞的提取,其目的是去除组织内的红细胞,使目的细胞群进一步纯化。其作用机制为：红细胞内有大量碳酸酐酶,可自发将NH₃转化为NH₄⁺,CO₂转化为HCO₃^-,促使胞外NH₃和CO₂连续内流造成细胞裂解。 基质血管成分：脂肪组织中除了含有成熟脂肪细胞外,还包含一组混杂的细胞群,即基质血管成分。基质血管成分包括血管内皮细胞、脂肪祖细胞、成纤维细胞、周细胞、脂肪干细胞,造血干细胞、红细胞等,其具有多向分化潜能及促进组织血管再生等功能,在组织及器官的再生、修复中具有极大的应用前景。 背景：脂肪干细胞的提取及纯化流程尚未建立统一标准。最常用的纯化脂肪干细胞的方法是利用红细胞裂解液处理基质血管成分。但这一步骤是否对脂肪干细胞存在不良影响仍缺乏证据,是否有利于未来临床应用仍有待探讨。 目的：比较氯化铵红细胞裂解液法和非裂解法提取脂肪干细胞的效率,并进一步比较两种方法提取脂肪干细胞的生物学特性。 方法：收集吸脂手术患者脂肪组织,经Ⅰ型胶原酶消化后,利用或不用氯化铵红细胞裂解液对基质血管成分进行纯化,Muse^TM细胞状态分析仪对活细胞计数及活细胞比例评估;将基质血管成分接种后培养人脂肪干细胞至第2代,光学显微镜观察脂肪干细胞形态,流式细胞学分析脂肪干细胞表型,CCK-8法绘制细胞增殖曲线,成脂及成骨培养基诱导后油红O及茜素红染色法分别评估成脂、成骨分化能力。该实验经中国医学科学院整形外科医院伦理委员会批准,并与患者签署相关知情同意书。 结果与结论：①与裂解组相比,非裂解组提取即刻的基质血管成分中非红活细胞数更多,活细胞百分比更大;②两组脂肪干细胞均呈梭形、鱼群状排列;③两组细胞均高表达CD90、CD73、CD105等细胞表面抗原,低表达或不表达CD11b、CD34、CD19、CD45、HLA-DR等细胞表面抗原;④非裂解组细胞增殖速度更快,成脂及成骨能力两组间无明显区别;⑤结果表明,利用氯化铵红细胞裂解液法提取基质血管成分降低了脂肪干细胞提取效率,抑制了脂肪干细胞增殖能力。非裂解过程不影响脂肪干细胞表型及成脂、成骨分化能力。因此不建议在人脂肪干细胞提取过程中进行氯化铵法红细胞裂解。 ORCID: 0000-0002-8958-4975(李梓菲) 中国组织工程研究杂志出版内容重点：干细胞;骨髓干细胞;造血干细胞;脂肪干细胞;肿瘤干细胞;胚胎干细胞;脐带脐血干细胞;干细胞诱导;干细胞分化;组织工程     

间断性低氧暴露对红细胞参数及血清HIF-1α、EPO的影响

目的:探讨间断性低氧暴露及复氧休息对红细胞参数及血清低氧诱导因子-1α(HIF-1α)、促红细胞生成素(EPO)的影响.方法:制备间断性低氧动物模型,检测全血RBC、Hb、HCT红细胞参数,采用ELISA法检测血清HIF-1α、EPO水平,结合现场调查,检测间断性高原作业人员红细胞参数及EPO水平.结果:IH7、14、21、28 d组大鼠RBC、Hb、HCT水平明显高于常氧对照组(P<0.05),复氧后各参数水平下降.IH3、7、14 d组HIF-1α高于常氧对照组(P<0.05),EPO在IH3、7 d组高于对照组(P<0.05),复氧后HIF-1α、EPO水平下降.8个月组高原作业人员RBC水平高于平原对照组(P<0.05),Hb在2年组高于平原对照组(P<0.05).HCT与RBC大致呈同一规律,且2年组HCT仍明显高于平原对照组(P<0.05).与平原对照组比较,各组EPO的差异不显著.结论:间断性低氧暴露可以增加血清HIF-1α、EPO的含量,提高红细胞数量和血红蛋白的浓度,并随低氧周期的延长存在一定变化规律;复氧休息有利于低氧后机体的调整,使升高的红细胞参数及HIF-1、EPO水平下降.     

促红细胞生成素基因修饰内皮祖细胞移植治疗下肢动脉闭塞：磁标记MR成像评价

文章快速阅读：文题释义： 内皮祖细胞：是存在于外周血及骨髓中的重要前体细胞,是能够特异性归巢于血管新生组织并进行分化、增殖成为成熟内皮细胞的一群祖细胞,其在不同环境中可向不同的方向进行分化。 促红细胞生成素：是糖蛋白中的一种,可对哺乳动物中红细胞的生成进行调节,主要由肾小管周细胞产生,也有少部分来自于肝脏,主要功能是使延缓细胞凋亡,其可以协同其他生长因子加速红系组细胞的增殖及成熟,并能促进骨髓中红细胞的释放。 摘要 背景：促红细胞生成素及内皮祖细胞移植均对下肢动脉闭塞有一定的治疗作用。 目的：探讨超顺磁氧化铁纳米颗粒(super paramagnetic iron oxide,SPIO)标记的内皮祖细胞体外促红细胞生成素基因修饰效果及体外磁共振成像的可行性。 方法：将对数生长期的大鼠骨髓来源内皮祖细胞分4组培养,内皮祖细胞组,SPIO标记转染组将pcDNA3-EPO 重组质粒并转染至内皮祖细胞,随后进行SPIO标记;SPIO标记空载病毒组将空质粒转染至内皮祖细胞,随后进行SPIO标记;SPIO标记内皮祖细胞组直接进行SPIO标记。采用4.7 T MR成像SPIO标记的内皮祖细胞;检测4组细胞增殖、细胞周期分布及促红细胞生成素蛋白表达。 结果与结论：①MR成像：T1WI、T2WI、T2*WI序列均见细胞信号降低,随着细胞数目增多,信号降低逐渐明显;相同数量级细胞,T1WI信号降低最弱,T2*WI信号降低最明显;T1WI、T2WI、T2*WI所能检测到的最小细胞数分别为2×10⁴、1×10⁴、0.5×10⁴;②细胞增殖、细胞周期分布：3组标记内皮祖细胞增殖、细胞周期分布与内皮祖细胞组比较差异均无显著性意义;③促红细胞生成素蛋白表达：仅SPIO标记转染组可见促红细胞生成素蛋白表达;④结果表明：SPIO标记的内皮祖细胞体外促红细胞生成素基因修饰后对细胞增殖、细胞周期无影响,4.7 T MR能够在体外对SPIO标记的促红细胞生成素基因修饰内皮祖细胞成像。   中国组织工程研究杂志出版内容重点：干细胞;骨髓干细胞;造血干细胞;脂肪干细胞;肿瘤干细胞;胚胎干细胞;脐带脐血干细胞;干细胞诱导;干细胞分化;组织工程 ORCID: 0000-0002-2568-7449(徐广宇)     

低氧预处理骨髓间充质干细胞耐受缺血缺氧的能力

背景：有研究表明骨髓间充质干细胞的生理环境氧体积分数低于常规培养用的20%-21%,适度低氧体积分数下,骨髓间充质干细胞表现出促进生长增殖,保持分化潜能的特性。 目的：观察低氧预处理后的大鼠骨髓间充质干细胞的生物学特性,以期为低氧预处理后的骨髓间充质干细胞体内移植治疗寻找体外依据。 方法：将大鼠骨髓间充质干细胞传代接种后置于体积分数1%O₂,5%CO₂的低氧培养箱内培养,以体积分数20%O₂,5%CO₂常氧培养的骨髓间充质干细胞同样封闭作为对照。 结果与结论：MTT检测显示,在低氧条件下培养的经低氧预处理的骨髓间充质干细胞较常氧条件下培养的细胞在贴壁后会经历一个相对较长时间的潜伏期,随后才进入指数生长期,体积分数1%O₂为非致死性的培养条件。锥虫蓝染色显示,封闭无血清条件下,两组细胞存活率均随着时间的推移而降低(P < 0.05),而常氧组下降更快。流式细胞仪检测显示,低氧组的细胞表面分子标记物CD29(+),CD90(+),CD31(-),CD45(-)的表达与低氧预处理前差异无显著性意义,未向血管内皮细胞分化。实时定量PCR和酶联免疫实验检测结果显示,低氧预处理48 h后,骨髓间充质干细胞中血管内皮生长因子mRNA和蛋白的表达均升高(P < 0.05)。Western-blot检测显示,低氧预处理24-48 h后,骨髓间充质干细胞中缺氧诱导因子1α的蛋白表达明显增多(P < 0.05)。证实,体积分数1% O₂能短暂抑制骨髓间充质干细胞的增殖,但不会产生致死性效应,可以作为低氧预处理的氧体积分数。体积分数1% O₂预处理48 h后,骨髓间充质干细胞的表型未发生明显变化,仍维持其干性。低氧预处理提高骨髓间充质干细胞对缺血缺氧的耐受能力,机制可能与低氧诱导因子1α表达增多有关。中国组织工程研究杂志出版内容重点：干细胞;骨髓干细胞;造血干细胞;脂肪干细胞;肿瘤干细胞;胚胎干细胞;脐带脐血干细胞;干细胞诱导;干细胞分化;组织工程全文链接：     

促红细胞生成素基因修饰骨髓间充质干细胞移植治疗大鼠脑梗死

背景：促红细胞生成素具有神经元的保护及促进神经再生的作用。目的：观察促红细胞生成素修饰的骨髓间充质干细胞尾静脉移植对大鼠脑梗死的治疗效果。方法：用Western blot鉴定外源人促红细胞生成素基因在骨髓间充质干细胞中的表达。采用线栓法建立大鼠大脑中动脉阻塞模型,模型组尾静脉注射PBS、骨髓间充质干细胞组注射骨髓间充质干细胞悬液,促红细胞生成素-骨髓间充质干细胞组注射转染了促红细胞生成素的骨髓间充质干细胞悬液。移植后3 d及移植后1,2,3,4 周行改良神经功能评分,检测神经功能的损伤情况。移植后4 周将大鼠麻醉后断头取脑,RT-PCR检测脑组织中bcl-2/bax基因表达变化,用原位末端标记法测定细胞凋亡情况、苏木精-伊红染色及荧光显微镜观察PKH26标记的骨髓间充质干细胞的存活和分布情况。结果与结论：Western blot结果显示,转染人促红细胞生成素基因的骨髓间充质干细胞体外能表达促红细胞生成素蛋白。移植后1-4周,骨髓间充质干细胞组和促红细胞生成素-骨髓间充质干细胞组神经缺损评分明显低于模型组(P < 0.05,P < 0.01)。与骨髓间充质干细胞组及模型组相比,大鼠脑梗死区组织促红细胞生成素-骨髓间充质干细胞组bcl-2基因的表达明显增高(P < 0.05),bax基因的表达明显降低(P < 0.05),凋亡细胞明显减少,PKH26阳性细胞数明显增多(P < 0.05)。结果证实,促红细胞生成素修饰的骨髓间充质干细胞尾静脉移植对脑梗死大鼠脑梗死疗效较好。中国组织工程研究杂志出版内容重点：干细胞;骨髓干细胞;造血干细胞;脂肪干细胞;肿瘤干细胞;胚胎干细胞;脐带脐血干细胞;干细胞诱导;干细胞分化;组织工程全文链接：     

慢性肾功能衰竭患者红系祖细胞功能及贫血机制的研究

用慢性肾功衰患者透析前、透析后的各自混合血浆分别与ＣＲＦ患者及正常人骨髓红系祖细胞培养，测定血清红细胞生成素，放免法测定血清叶酸和铁蛋白，并计数外周血片异形红细胞数。结果表明：①未透析患者红系祖细胞在正常混合血浆培养下与正常对照无差别（Ｐ＞０．０５）；②透析前、后的血浆均对红系祖细胞有抑制作用（Ｐ＜０．０５）；③但未透、腹透和血透三组之间对红系祖细胞的影响无明显差别（Ｐ＞０．０５）；④未透ＣＲＦ患     

重组人促红细胞生成素与骨髓间充质干细胞的迁移及黏附

背景：促红细胞生成素可促进内皮祖细胞的增殖分化并增强其黏附性。 目的：观察重组人促红细胞生成素干预对人骨髓间充质干细胞迁移和黏附能力及相关细胞信号传导通路的影响。 方法：体外培养人骨髓间充质干细胞,使用重组人促红细胞生成素干预第6代人骨髓间充质干细胞。分别用PI3K/Akt通路特异抑制剂Ly294002或p38MAPK通路特异激动剂anisomycin或ERK1/2通路特异抑制剂U0126预处理。 结果与结论：重组人促红细胞生成素可使人骨髓间充质干细胞的PI3K/Akt通路磷酸化水平升高,抑制p38MAPK通路磷酸化水平,对人骨髓间充质干细胞的ERK通路和总Akt、总p38MAPK水平无明显影响。重组人促红细胞生成素作用组中迁移细胞数目显著高于对照组(P < 0.01),黏附细胞数亦明显增加(P < 0.01),PI3K/AKT通路特异抑制剂Ly294002预处理后重组人促红细胞生成素对迁移能力的作用消失,p38MAPK通路特异激动剂anisomycin预处理对两种作用影响均不明显。提示重组人促红细胞生成素具有增强人骨髓间充质干细胞迁移和黏附能力的作用,其增强迁移能力的作用与激活人骨髓间充质干细胞的PI3K/Akt通路有关,但是它对黏附能力的作用与PI3K/Akt和p38MAPK通路均无关。     

Comparison of hemolglobin dissolved in plasma and contained in red cells for maintaining the circulation and respiration

The basic circulatory and respiratory indices were compared in two series of cats. In the animals of series I the blood was completely replaced by an 8% solution of human hemoglobin (Hb), purified from stroma and procoagulant activity, whereas in the animals of series II the blood was diluted with dextran to an Hb concentration of 8 g%. The solution readily became saturated in the lungs and gave up its oxygen in the tissues, but did so much less readily than Hb contained in red cells. Dissolved Hb did not completely meet the oxygen demand of the body, and the animals developed hypoxia. Moderate anemic hypoxia caused by dilution of the blood with dextran was easily compensated. An Hb solution can be regarded as the basis or first stage in the creation of a blood substitute and oxygen carrier.Laboratory of Pathological Physiology, Central Institute of Hematology and Blood Transfusion, Ministry of Health of the USSR, Moscow. (Presented by Academician of the Academy of Medical Sciences of the USSR N. A. Fedorov.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 86, No. 8, pp. 131–133, August, 1978.     

高原红细胞增多症患者及藏,汉族正常人血氧解离曲线的对比测定

用同时测定血氧分压和血氧饱和度法直接测定了藏、汉族及高原红细胞增多症患者的血氧解离曲线。结果发现高原红细胞增多症患者较正常藏、汉族的血氧解离曲线明显右移,而藏、汉族间无明显差异。提示高原红细胞增多症者个体的血红蛋白与氧的亲和力特征可能与其血氧解离曲线的右移有关而与民族无关。     

Micronuclei in binucleated lymphocytes of mice following exposure to gamma radiation

Experiments were designed to investigate the induction of micronuclei (MN) in mouse peripheral blood lymphocytes (PBLs) after in vitro or in vivo exposure to 60Co gamma radiation. For the in vitro experiments, 4 ml of blood from male C57BL/6J mice were either irradiated in 6 ml Falcon culture tubes as whole blood or isolated to obtain mononuclear leukocytes (MNLs) that were pelleted by centrifugation and then irradiated in RPMI 1640. For the in vivo analysis, mice received whole body irradiation, blood was obtained by cardiac puncture, and the MNLs were isolated for each mouse. Exposures were at a rate of 0.82 to 0.90 Gy/min to yield doses of 0.5, 1, 2, 3, or 4 Gy. MNLs were cultured using cytochalasin B for MN analysis in binucleated PBLs. There was a significant dose-dependent increase in MN observed at all doses. Dose-response curves for the in vivo and in vitro whole blood experiment were not significantly different. However, for isolated pelleted MNLs irradiated in vitro, the MN frequency at 4 Gy was less than one-half that seen in the in vivo experiment. The large difference in MN response is thought to be due to the radioprotective effect of hypoxia.     

便携式富氧机在模拟低氧环境中对机体血气的影响

目的：检测自主研发的便携式富氧机在模拟低氧环境中的应用效果。方法：采用自身前后对照研究,用低压舱模拟海拔4000m的低氧环境,16名受试者分别在使用便携式富氧机前后抽取桡动脉血,检测PH值、氧分压（PaO：）、二氧化碳分压（PaCO：）、碳酸氢根（HCOf）、二氧化碳总量（TCO2）和血氧饱和度（SaO2）等6个主要的血气（BloodGas）指标,进行统计学分析。结果：使用富氧机后,受试者动脉血Pa02和Sa02明显升高（P〈O．01）,PCO2、TCO2、HC03^-的变化没有统计学意义（P〉0．01）。结论：使用便携式富氧机能显著提高低氧环境中机体血液中的氧含量,使用安全有效。     

生物携氧治疗剂的研究：作用与应用

文题释义：生物携氧治疗剂：是指具有载氧气功能、维持血液渗透压和酸碱平衡及扩充血容量的人工制剂。目前主要有氟碳化合物和血红蛋白类氧载体两大类。与简单的扩容剂相比,生物携氧治疗剂除能维持血液渗透压、酸碱平衡和血容量外,还具有较好的携氧能力,能向局部缺氧组织输氧。是临床上一种具有广阔的应用前景的携氧制剂。 血红蛋白类氧载体(Hemoglobin-based oxgen carriers,HBOCs)：是一类通过血红蛋白分子表面化学修饰或分子间交联而形成分子量较大的血红蛋白制品,原料血红蛋白主要来源于人或动物血,目前应用较为广泛的是戊二醛聚合猪血红蛋白(pPolyCHb)和戊二醛聚合牛血红蛋(HBOC-201)。 背景：健康人献血虽然一定程度地缓解了临床用血的燃眉之急,但是单纯依靠健康人献血已不能从根本上解决血源短缺和血液安全性的问题。 目的：结合生物携氧治疗剂开发的意义,对生物携氧治疗剂所独有的特点进行阐述,总结近年来对生物携氧治疗剂的研究现状及应用进展,为进一步研究生物携氧治疗剂的作用及临床应用提供一定的理论基础。 方法：作者检索CNKI、万方、Pub Med等数据库中自2015年1月至2019年8月的相关文章,英文检索词为“blood substitute, hemoglobin oxygen carrier, artificial blood,oxygen-carrying therapeutic agent”,中文检索词为“血液代用品,血红蛋白类氧载体,人工血液,携氧治疗剂”,检索文献类型为研究原著、综述。初检文章418篇,再经过严格筛选后,对符合要求的46篇文献进行分类综述。 结果与结论：生物携氧治疗剂的临床效果较好,可维持血液渗透压、酸碱平衡和血容量,还具有较好的携氧能力,能向局部缺氧组织输氧并维持较长时间。它还具有易于贮存、便于运输等特点。生物携氧治疗剂在外科手术中得到广泛的应用,对扩充血容量、加快术后恢复有很大帮助,故其研发对于外科创伤及复苏、失血性休克、恶性贫血、心肌梗死等疾病均具有重要意义,并体现出良好的临床应用前景。 ORCID: 0000-0002-0365-4638(黄文华) 中国组织工程研究杂志出版内容重点：人工关节;骨植入物;脊柱;骨折;内固定;数字化骨科;组织工程     

Effects of cervical sympathetic stimulation on cerebral and ocular blood flows during hemorrhagic hypotension and moderate hypoxia

The effect of cervical sympathetic stimulation upon regional blood flows was investigated in albino rabbits during graded hemorrhagic hypotension and mild to moderate hypoxic hypoxia. Regional blood flows were determined using labelled microspheres. Cerebral blood flow (CBF) decreased in response to progressive hypotension and increased considerably during hypoxia (100–200%). Unilateral sympathetic stimulation did not change the ipsilateral cerebral flow responses under either condition. There was a greater tendency to autoregulate down to lower blood pressures in deep than in superficial cerebral structures. During hypoxia cortical gray matter blood flow increased relatively more than did white matter blood flow. Blood flow in different parts of the eye decreased during hypotension and tended to increase during hypoxia. Unilateral sympathetic stimulation reduced tlow rates on the stimulated side (10–50% of control side) under both conditions. The vasoconstrictory effect upon retinal blood flow tended. however, to be less during hypoxia. Dural blood flow showed a poor autoregulation and also no consistent vasodilatory response upon hypoxia. Sympathetic stimulation had a very marked effect. The results suggest that the cervical sympathetic nerves do not have any appreciable effect upon cerebral circulation during profound hypotensive and moderate hypoxic states. Dural and most ocular blood flows seem. however. to be clearly affected by sympathetic stimulation even under these extreme conditions.     

Circulatory effects of apnoea in elite breath‐hold divers

Aim: Voluntary apnoea induces several physiological adaptations, including bradycardia, arterial hypertension and redistribution of regional blood flows. Elite breath‐hold divers (BHDs) are able to maintain very long apnoea, inducing severe hypoxaemia without brain injury or black‐out. It has thus been hypothesized that they develop protection mechanisms against hypoxia, as well as a decrease in overall oxygen uptake. Methods: To test this hypothesis, the apnoea response was studied in BHDs and non‐divers (NDs) during static and dynamic apnoeas (SA, DA). Heart rate, arterial oxygen saturation (SaO₂), and popliteal artery blood flow were recorded to investigate the oxygen‐conserving effect of apnoea response, and the internal carotid artery blood flow was used to examine the mechanisms of cerebral protection. Results: The bradycardia and peripheral vasoconstriction were accentuated in BHDs compared with NDs (P < 0.01), in association with a smaller SaO₂ decrease (?2.7% vs. ?4.9% during SA, P < 0.01 and ?6% vs. ?11.3% during DA, P < 0.01). Greater increase in carotid artery blood flow was also measured during apnoea in BHDs than in controls. Conclusion: These results confirm that elite divers present a potentiation of the well‐known apnoea response in both SA and DA conditions. This response is associated with higher brain perfusion which may partly explain the high levels of world apnoea records.     

Role of Cholinergic Structures in Individual Resistance of Rat Circulatory System to Posthemorrhagic Hypoxia

Experiments employing ultrasound technique showed that nonselective blockade of central muscarinic cholinoceptors with amizyl significantly increases the number and lifespan of rats highly resistant to acute massive blood loss. This pretreatment increased individual resistance of the circulatory system to posthemorrhagic hypoxia (blood pressure and portal blood flow rate). Preliminary blockade of central nicotinic cholinoceptors and peripheral muscarinic cholinoceptors with cyclodol and methacin, respectively, had no effect on the percentage of rats highly and low resistant to acute blood loss. Preliminary blockade of peripheral muscarinic cholinoceptors with methacin prevented the decrease in the cardiac output in low resistant animals during the posthemorrhagic period. __________ Translated from Byulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 140, No. 8, pp. 142–145, August, 2005     

Dependence of blood pressure changes in cats during acute hypoxic hypoxia on the type of carotid sinus reflex

The type and degree of blood pressure changes in cats were studied in acute experiments under conditions of acute hypoxic hypoxia (40% decrease in oxygen partial pressure). During hypoxia, blood pressure increased in cats with pressor type of the carotid sinus reflex and decreased in animals with depressor type of this reflex. Our results indicate that the direction and degree of hypoxic changes in blood pressure in animals coincide with variations in this parameter in response to the carotid sinus reflex. __________ Translated from Byulleten’ Eksperimental’noi Biologii i Meditsiny, Vol. 142, No. 11, pp. 490–493, November, 2006     

An animal model of the relationship between systemic hypertension and repetitive episodic hypoxia as seen in sleep apnoea

SUMMARY  Multiple factors may be responsible for acute and chronic blood pressure changes during obstructive sleep apnoea. A popular hypothesis is that recurrent episodic hypoxia stimulates chemoreceptors which, in turn, cause sympathetically mediated vasoconstriction and perhaps long-term vascular remodelling. Disruption of sleep architecture secondary to frequent arousals may also cause chronic stress which may contribute to diurnal hypertension. A less likely factor elevating blood pressure is the effect of abrupt intra-thoracic pressure changes on venous return and cardiac output. The rat responds to chronic, recurrent episodic hypocapnic hypoxia (12-s bursts of nitrogen followed by air into Plexiglas chambers, every 30 s, 7h d^-1, 2–4% nadir ambient oxygen) with sustained increase in diurnal blood pressure (10–14 mmHg). Subsequent studies reveal that carotid sinus nerve section (chemodener-vation) and chemically induced peripheral sympathetic denervation with the neurotoxin 6-OH dopamine both eliminate this blood pressure-elevating effect of chronic episodic hypoxaemia. Using this model, Sprague-Dawley rats have been challenged with both eucapnic hypoxia and asphyxia and failed to show an additional blood pressure elevation above that caused by hypoxia (hypocapnic) alone. It appears that hypocapnic hypoxia creates a maximal stimulus to the sympathetic nervous system to which the addition of hypercarbia does not increase the blood pressure response. An alternative explanation is that the rat has protective mechanisms that limit the diurnal blood pressure response from further increase.