治疗性高碳酸血症对大鼠移植肺细胞凋亡的影响

目的探讨治疗性高碳酸血症对移植肺细胞凋亡的影响及其可能的机制。方法26只Wistar大鼠,供体鼠和受体鼠各13只,肺移植成功后随机分为2组：对照组（n=6）和治疗组（n= 7）。对照组再灌注期间吸入50%N2-50%O2混合气体;治疗组再灌注期间吸入40%N2-60%O2- 100%CO2混合气体,调节吸入二氧化碳和氧气的流量,维持吸入氧浓度50%,动脉血二氧化碳分压（PaCO2）80～100 mm Hg。记录受体鼠机械通气15 min时平均动脉压（MAP）、PaCO2和动脉血氧分压（PaO2）作为基础值,再灌注期间每15分钟记录1次,直至实验结束。再灌注90 min时放血处死大鼠,采用考马斯亮蓝法测定支气管肺泡灌洗液（BALF）蛋白浓度;取左肺组织,计算湿/干重比;采用免疫组化法测定Bax、Bcl-2的表达;采用TUNEL法检测细胞凋亡情况。结果与基础值比较,再灌注期间对照组MAP和PaO2降低（P〈0.05）;与对照组比较,再灌注期间治疗组MAP、PaCO2和PaO2升高,BALF蛋白浓度、肺组织W/D、Bax表达和细胞凋亡指数降低（P〈0.05）,Bcl-2表达差异无统计学意义（P〉0.05）。结论治疗性高碳酸血症可抑制大鼠移植肺细胞凋亡,其机制与下调Bax蛋白表达有关。     

MAPK 通路抑制剂对低氧高二氧化碳性肺动脉收缩的影响

目的： 观察肺主动脉环、二级肺动脉环在急性低氧高二氧化碳介质中张力的变化；探讨 MAPK 信号通路抑制剂 U0126、SB203580 对低氧高二氧化碳性肺血管收缩的影响。方法: 制备离体 SD 大鼠肺主动脉环、二级肺动脉环。分别观察肺主动脉环、二级肺动脉环在常氧及急性低氧高二氧化碳介质中的张力变化；在急性低氧高二氧化碳条件下分别用 U0126、SB203580 孵育二级肺动脉，观察各自对低氧高二氧化碳性肺动脉收缩的影响。结果: 在常氧条件下,肺主动脉、二级肺动脉张力均无明显变化。急性低氧高二氧化碳条件下二级肺动脉发生双向性收缩反应，肺主动脉只在低氧高二氧化碳早期出现较明显的收缩峰，后期则变化不明显。二级肺动脉分别经ERK1/2上游激酶抑制剂 U0126、p38 MAPK 通路抑制剂 SB203580 孵育后，Ⅱ期持续收缩幅度明显下降（P<0.05)，Ⅰ期快速收缩峰、Ⅰ期舒张均没有明显变化。结论: 在离体条件下，急性低氧高二氧化碳（PO₂ = 30-35 mmHg，PCO₂=55-60 mmHg)可使肺主动脉出现早期快速收缩，并可使二级肺动脉环发生双向性收缩反应；急性低氧高二氧化碳条件下，U0126、SB203580 均能减弱二级肺动脉环的Ⅱ期持续收缩反应。这为临床治疗缺氧和高碳酸血症引起的肺血管收缩及肺动脉高压提供了理论依据。     

低氧和高二氧化碳作用下肺动脉高压形成过程中骨桥蛋白表达与分布的实验研究

目的： 观察慢性低O2高CO2大鼠肺动脉骨桥蛋白（OPN）及其基因的表达与分布情况，探讨OPN在肺动脉高压发病机制中的作用。方法： 48只雄性SD大鼠随机分为4组：即正常对照组（NC组），低O2高CO2 1周、2周和4周组（1HH、2HH和4HH）。采用RT-PCR法测定不同低O2高CO2 组大鼠离体肺动脉和肺组织骨桥蛋白（OPN）mRNA，免疫组织化学染色法测定肺细小动脉骨桥蛋白分布表达情况，ELISA 法定量测定肺组织匀浆OPN水平，Western blotting 法测定离体肺动脉OPN表达水平。结果： ①低O2高CO2各组大鼠mPAP和RV/LV+S均明显高于NC组（P<0.01），4组大鼠间mCAP比较无显著差异（P>0.05）；②低O2高CO2 各组大鼠肺组织和离体肺主动脉OPN mRNA表达水平显著高于对照组（均P<0.01）；③免疫组化法显示NC组大鼠肺组织OPN表达主要见于支气管、肺泡上皮细胞内，1HH组大鼠肺细小动脉内皮细胞、平滑肌细胞以及周围巨噬细胞均见有OPN的表达，其中以中膜平滑肌细胞最为明显，而2HH和4HH组大鼠OPN表达更加明显, 低O2高CO2 各组肺细小动脉OPN相对含量与对照组比较有显著差异（均P<0.01），且随缺氧时间的延长，骨桥蛋白表达也呈增高趋势；④ 低O2高CO2 各组大鼠肺组织匀浆OPN含量分别为正常对照组的1.69倍、2.28倍和2.87倍（均P<0.01）；⑤ Western blotting 分析1HH、2HH和4HH各组大鼠离体肺动脉OPN表达明显增强，与NC组比较有显著差异（均P<0.01）。结论： 慢性低O2高CO2能够刺激大鼠肺组织和肺动脉OPN及其基因表达增强，OPN可能在慢性低O2高CO2性肺动脉高压发病的病理和病理生理过程中起着重要的作用。     

Ventilatory control studied with circulatory occlusion during exercise recovery

Summary Mechanisms involved in the control of pulmonary ventilation were studied in seven male subjects following 6 min of exercise on a cycle ergometer at 98w. Circulation to the legs was occluded by thigh cuffs (27 kPa) during the last 15 s of exercise and the subsequent 4 min of recovery. Respiratory gas exchange and the tidal partial pressures of O₂ and CO₂ were measured breathby-breath. The results were compared to control studies without occlusion. There was a significant increase in both systolic and diastolic blood pressures during occluded recovery. Following occlusion systolic pressure remained elevated while diastolic pressure returned to control values. Occlusion during recovery caused hyperventilation during the first 1.5 min after exercise as evidenced by significantly higher , P_ETO₂, and lower P_ETCO₂. Following the release of the cuffs P_ETCO₂, , and heart rate all increased significantly above control values, while P_ETO₂ decreased. P_ETCO₂ rose abruptly 14.5±0.9 s after the release of the cuffs. Marked increases inV _E and heart rate were seen, and occurred 30.8±1.5 s and 12.8±1.3 s, respectively, after cuff release. The 16.3±1.4 s lag between the increase in P_ETCO₂ and after occlusion suggests that the ventilatory response to a sudden load of hypercapnic blood is not mediated by a pulmonary chemoreceptor. Other receptors, probably the peripheral chemoreceptors, appear to be responsible for hypercapnic hyperventilation.     

肺动脉高压大鼠一氧化氮及过氧化氢依赖的可溶性鸟苷酸环化酶通路的变化

目的：观察低O2高CO2对血浆一氧化氮（NO）、肺组织超氧化物歧化酶（SOD）、过氧化氢酶（CAT）、可溶性鸟苷酸环化酶(sGC)活性以及cGMP含量的变化，探讨NO-sGC和H2O2-sGC通路于肺动脉高压中的作用。 方法： 复制低O2高CO2 1、2、4周组及对照组大鼠模型。测定平均肺动脉压（mPAP）。比色法测定血浆一氧化氮（NO）、肺组织超氧化物歧化酶（SOD）、过氧化氢酶（CAT）活性，酶动力学分析基础及过氧化氢（H2O2）及硝普钠（SNP）激活的肺组织sGC酶活性，［125I］-放射免疫法检测肺组织cGMP含量。 结果： 低O2高CO2 1、2、4周组mPAP均明显高于对照组（均P<0.01）；血浆NO、肺组织SOD、CAT活性、基础sGC活性、过氧化氢（H2O2）及硝普钠（SNP）激活的sGC活性和肺组织cGMP含量均显著低于对照组（分别P<0.05, P<0.01）。 结论： 低O2高CO2抑制NO-sGC和H2O2-sGC通路参与肺动脉高压的形成与发展。     

Impaired cerebrovascular reactivity is associated with recurrent stroke in patients with severe intracranial arterial stenosis: A C02 BOLD fMRI study

Background and PurposeSevere intracranial atherosclerotic stenosis (SIAS) remains at risk of recurrent ischemic events despite intensive medical management. Exhausted cerebrovascular reserve seems to be associated with higher risk of recurrent stroke.Materials and MethodsWe used whole brain MRI to estimate basal perfusion using dynamic susceptibility contrast and cerebrovascular reactivity (CVR) to hypercapnic challenge (CO2 inhalation) using BOLD contrast, in 20 patients with symptomatic SIAS (> 70%) of the middle cerebral artery (MCA) or the distal internal carotid artery. We studied relationships between individual clinical, biological, radiological baseline characteristics, recurrent ischemic events, basal perfusion parameters (mean transit time, delay, time to peak, cerebral blood flow and volume), and CVR measured in MCA territories (CVRMCA), and reported using laterality indices (LI).ResultsTen patients had an impaired CVR with (|LI| CVRMCA ≥ 0.08). During a mean follow-up of 3.3 years, all recurrent ipsilateral ischemic events occurred within the first year. They were more frequent in impaired CVRMCA group (n = 7/10 patients) than in normal CVRMCA group (n = 1/10), with different survival curves (log rank, P = 0.007).ConclusionImpaired CVR is associated with an increased rate of recurrent stroke in patients with symptomatic SIAS. CVR mapping should be used as a well tolerated method to select higher-risk patients in further therapeutic trials such as endovascular procedures.     

Experimental strategies to improve in vitro models of renal ischemia

Ischemia has elicited a great deal of interest among the scientific community due to its role in life-threatening pathologies such as cancer, stroke, acute renal failure, and myocardial infarction. Oxygen deprivation (hypoxia) associated with ischemia has recently become a subject of intense scrutiny. New investigators may find it challenging to induce hypoxic injury in vitro. Researchers may not always be aware of the experimental barriers that contribute to this phenomenon. Furthermore, ischemia is associated with other major insults, such as excess carbon dioxide (hypercapnia), nutrient deprivation, and accumulation of cellular wastes. Ideally, these conditions should also be incorporated into in vitro models. Therefore, the motivation behind this review is to: i. delineate major in vivo ischemic insults; ii. identify and explain critical in vitro parameters that need to be considered when simulating ischemic pathologies; iii. provide recommendations to improve experiments; and as a result, iv. enhance the validity of in vitro results for understanding clinical ischemic pathologies. Undoubtedly, it is not possible to completely replicate the in vivo environment in an ex vivo model system. In fact, the primary goal of many in vitro studies is to elucidate the role of specific stimuli during in vivo pathological events. This review will present methodologies that may be implemented to improve the applicability of in vitro models for understanding the complex pathological mechanisms of ischemia. Finally, although these topics will be discussed within the context of renal ischemia, many are pertinent for cellular models of other organ systems and pathologies.     

低O2高CO2对大鼠肺中小动脉可溶性鸟苷酸环化酶基因及其蛋白表达的影响

目的:探讨慢性低O₂高CO₂时大鼠肺动脉可溶性鸟苷酸环化酶(sGC)基因及其蛋白表达的变化。方法:复制大鼠低O₂高CO₂肺动脉高压模型, 免疫组织化学技术观察低O₂高CO₂肺动脉高压1、2、4周组及对照组肺中小动脉sGCα₁、β₁亚基蛋白的表达, 原位杂交技术观察肺中小动脉sGCα₁亚基mRNA的表达。结果:低O₂高CO₂1、2、4周组肺中小动脉sGCα₁、β₁亚基蛋白及α₁亚基mRNA表达弱于对照组(均P＜0.01)。结论:低O₂高CO₂抑制肺中小动脉sGCmRNA及其蛋白的表达, 参与肺动脉高压形成与发展。