Inhibition of hypoxic pulmonary vasoconstriction of rats by carbon monoxide

Hypoxic pulmonary vasoconstriction (HPV), a unique response of pulmonary circulation, is critical to prevent hypoxemia under local hypoventilation. Hypoxic inhibition of K(+) channel is known as an important O(2)-sensing mechanism in HPV. Carbon monoxide (CO) is suggested as a positive regulator of Ca(2+)-activated K(+) channel (BK(Ca)), a stimulator of guanylate cyclase, and an O(2)-mimetic agent in heme moiety-dependent O(2) sensing mechanisms. Here we compared the effects of CO on the HPV (P(O(2)), 3%) in isolated pulmonary artery (HPV(PA)) and in blood-perfused/ventilated lungs (HPV(lung)) of rats. A pretreatment with CO (3%) abolished the HPV(PA) in a reversible manner. The inhibition of HPV(PA) was completely reversed by 1H-[1,2,4]oxadiazolo-[4,3-a]quinoxalin-1-one (ODQ), a guanylate cyclase inhibitor. In contrast, the HPV(lung) was only partly decreased by CO. Moreover, the partial inhibition of HPV(lung) by CO was affected neither by the pretreatment with ODQ nor by NO synthase inhibitor (L-NAME). The CO-induced inhibitions of HPV(PA) and HPV(lung) were commonly unaffected by tetraethylammonium (TEA, 2 mM), a blocker of BK(Ca). As a whole, CO inhibits HPV(PA) via activating guanylate cyclase. The inconsistent effects of ODQ on HPV(PA) and HPV(lung) suggest that ODQ may lose its sGC inhibitory action when applied to the blood-containing perfusate.     

K~ 通道在正常与慢性低氧大鼠低氧性肺血管收缩反应中的作用

目的 :探讨K 通道在慢性低氧致低氧性肺血管收缩反应降低中的作用。方法 :采用离体肺灌流实验 ,研究 4-AP(4-aminopyridine ,电压依赖性K 通道 -Kv阻滞剂 )、TEA(tetraethylamonium ,Ca2 激活性K 通道 -KCa阻滞剂 )、GLIB(glibenclamide,ATP敏感性K 通道 -KATP阻滞剂 )对正常与慢性低氧大鼠肺血管低氧反应的影响。结果 :4-AP、TEA均可使正常大鼠肺动脉基础压上升 ,且使其肺血管低氧反应明显增强 ;对于慢性低氧大鼠 ,其肺血管对低氧反应明显低下 ,4-AP、TEA升肺动脉基础压的作用明显低于对照鼠肺 ,GLIB也呈现升高肺动脉基础压力作用 ,4-AP、TEA、GLIB均可使肺血管低氧反应大大增强 ,增强的比例明显大于正常对照组。结论 :在离体灌流鼠肺HPV中 ,Kv、KCa的开放起调节作用 ,大鼠经慢性低氧后 ,肺血管反应性明显降低 ,可能与Kv、KCa、KATP在HPV中的调节作用相对增强有关     

不同食用油对大鼠肺血管反应性和慢性低氧性肺动脉高压的影响

本研究观察了豆油和猪油对大鼠肺血管反应性和慢性低氧性肺动脉高压的影响。大鼠进高脂饮食2月后,常压缺氧14天。缺氧时吸入气O_2浓度为10±0.5%,每天缺氧8小时。结果喂含15%豆油的高脂饮食的大鼠的平均肺动脉压<(?)pa,肺血管阻力(PVR)和肺血管对急性缺氧的反应性(△PVR%)均显著高于缺氧对照组,右心室肥大也较缺氧对照组严重。喂含15%猪油的高脂饮食或含7.5%豆油加7.5%猪油的高脂饮食的大鼠的Ppa,PVR,△PVR%以及右心室肥大程度与缺氧对照组大鼠无明显差别。血粘度和红细胞压积在慢性常压缺氧后均增高,但不同的高脂饮食对其影响不大。实验结果提示,富含豆油的高脂饮食增强大鼠的低氧性肺血管收缩反应,加重慢性低氧性肺动脉高压和右心室肥大。     

一氧化碳促进肺动脉平滑肌细胞血红素氧合酶基因的表达

目的:观察低浓度一氧化碳(CO)和低氧处理肺动脉平滑肌细胞(PASMC)后,血红素氧合酶(HO)基因表达的状况。方法:培养大鼠PASMC成功后并进行鉴定,应用免疫组织化学、逆转录聚合酶链式反应(RT-PCR)和Westernblot的方法研究低浓度CO和低氧作用后PASMC的HOmRNA及HO蛋白质含量。结果:①HO-1抗体免疫组织化学染色低氧组细胞胞浆呈黄色,中等强度;CO处理组的细胞胞浆呈棕黄色,强阳性,比低氧组的颜色显著深。HO-2抗体染色各组细胞胞浆均呈淡黄色,弱阳性。②低氧组细胞HO-1mRNA的表达水平为1.25±0.37,明显高于常氧组细胞(0.12±0.04);低浓度CO组细胞HO-1mRNA的表达水平为3.52±0.68显著高于低氧组。各组细胞HO-2mRNA的水平无明显差异。③低氧48h组细胞HO-1的蛋白含量为1.07±0.15,高于低氧24h组细胞(0.52±0.04);低浓度CO组细胞HO-1的蛋白含量为3.65±0.43,显著高于低氧组细胞,48h蛋白质含量为最高。结论:低浓度CO和低氧处理PASMC,可以促进HO-1mRNA和蛋白质的表达,而HO-1在细胞低氧损害中发挥调节作用,部分减轻低氧的损害。     

In vivo carbon monoxide exposure and hypoxic hypoxia stimulate immediate early gene expression

 This study aimed to examine the influence of acute tissue hypoxygenation on the expression of immediate early genes in different rat tissues. To this end male Sprague-Dawley rats were exposed to 0.1% carbon monoxide for 0.5, 1 and 6 h or to 9% oxygen for 6 h and mRNA levels for c-jun, c-fos, c-myc and EGR-1 were assayed by RNase protection in hearts, kidneys, livers and lungs. We found that hypoxia increased c-jun mRNA levels between twofold (lung) and eightfold (liver) in all organs examined; c-fos mRNA increased between threefold (lung) and 20-fold (heart); c-myc mRNA increased between twofold (lung) and sixfold (heart); and EGR-1 mRNA increased between twofold (lung) and sixfold (heart). Our findings suggest that acute tissue hypoxygenation is a general stimulus of the expression of immediate early genes in vivo. With regard to the sensitivity to hypoxia, organ differences appear to exist in that the lung is rather insensitive, whilst the heart is rather sensitive. Received: 25 February 1997 / Received after revision: 17 June 1997 / Accepted: 19 June 1997     

K+通道在正常与慢性低氧大鼠低氧性肺血管收缩反应中的作用

目的:探讨K⁺通道在慢性低氧致低氧性肺血管收缩反应降低中的作用。方法:采用离体肺灌流实验,研究4-AP(4-aminopyridine,电压依赖性K⁺通道-Kv阻滞剂)、TEA(tetraethylamonium,Ca²⁺激活性K⁺通道-K_Ca阻滞剂)、GLIB(glibenclamide,ATP敏感性K⁺通道-K_ATP阻滞剂)对正常与慢性低氧大鼠肺血管低氧反应的影响。结果:4-AP、TEA均可使正常大鼠肺动脉基础压上升,且使其肺血管低氧反应明显增强;对于慢性低氧大鼠,其肺血管对低氧反应明显低下,4-AP、TEA升肺动脉基础压的作用明显低于对照鼠肺,GLIB也呈现升高肺动脉基础压力作用,4-AP、TEA、GLIB均可使肺血管低氧反应大大增强,增强的比例明显大于正常对照组。结论:在离体灌流鼠肺HPV中,Kv、K_Ca的开放起调节作用,大鼠经慢性低氧后,肺血管反应性明显降低,可能与Kv、K_Ca、K_ATP在HPV中的调节作用相对增强有关。     

Carbonic anhydrase inhibitors and hypoxic pulmonary vasoconstriction

Acetazolamide and other related carbonic anhydrase (CA) inhibitors have had a long history of effectiveness in prevention and treatment of acute mountain sickness (AMS) and remain the standard of care for this indication. Despite many decades of CA inhibitor use for AMS, the possibility has never been seriously entertained that these drugs might also afford protection against high altitude pulmonary edema (HAPE). In this paper, I will present our evidence and supporting data of others, that acetazolamide has inhibitory effects on the hypoxic response of the pulmonary circulation that may be useful in HAPE. Data from pulmonary artery smooth muscle cells, isolated perfused lungs, and live unanethetized animals all point to a potent reduction in hypoxic pulmonary vasoconstriction (HPV) by acetazolamide that may have clinical utility in HAPE and possibly other pulmonary hypertensive disorders. Astonishingly, the efficacy of acetazolamide as a HPV inhibitor does not appear to be related to carbonic anhydrase inhibition, since other potent CA inhibitors have no effect on HPV either in the conscious dog or on hypoxic calcium (Ca(2+)) signalling in rat pulmonary artery smooth muscle cells, despite enzyme presence in these cells. Although we have not yet determined the mechanism of action for acetazolamide in HPV, we have ruled out actions on membrane L-type Ca(2+) channels, normoxic and hypoxic membrane potential and rho-kinase activation. Based upon these negative findings in isolated pulmonary artery smooth muscle cells and preliminary data in Ca(2+) free media we propose that acetazolamide may act at the level of Ca(2+) release from the sarcoplasmic reticulum, a process which initiates and amplifies cell membrane Ca(2+) channel opening. In further work, we have developed and will use a methylated analog of acetazolamide to yield a molecule lacking CA inhibiting activity, but which in most other respects (size, pK(a), heterocyclic ring structure, electrostatic charge distribution) is equivalent to acetazolamide.     

高镁饮食对大鼠缺氧性肺血管收缩反应和慢性缺氧性肺动脉高压的影响

本课题观察了高镁饮食对大鼠缺氧性肺血管收缩反应(HPV)和慢性缺氧性肺动脉高压的影响。大鼠进高镁饲料(每公斤普通饲料加镁1000mg)10周后,血浆镁浓度为2.58mEq/L,显著高于对照组大鼠的血浆镁浓度。慢性常压缺氧(吸入气含10%O_2,每天8小时,连续14天)后,与缺氧对照大鼠相比,进高镁饲料盼大鼠的平均肺动脉压(Ppa)和肺血管阻力(PVR)较低,肺血管对缺氧的反应性(△PVR%)较低,同时右心室肥大也较轻。血粘度和红细胞比积在慢性常压缺氧后均增高,但进高镁饲料大鼠的血粘度和红细胞比积与缺氧对照组大鼠无差别。结果表明,镁可以降低PVR和HPV,从而缓解由慢性缺氧引起的肺动脉高压和右心室肥大。     

蝮蛇抗栓酶对狗急性肺泡缺氧性肺动脉高压的影响

本文研究了蝮蛇抗栓酶对狗急性缺氧性肺动脉高压的作用。结果显示:蝮蛇抗栓酶可明显地降低肺循环阻力,剂量依赖性地减弱或抑制急性缺氧性肺血管收缩反应;但对体循环的影响较小,而且不改变PaO_2及PaCO_(2);血浆6-keto-PGF_(1α)浓度在静脉注射此酶后明显升高,但TXB_2则无显著改变。这些结果提示:蝮蛇抗栓酶可缓解缺氧性肺血管收缩痉挛,其机制可能与促进PGI_2的产生与释放有关。     

Tissue factor is associated with the nonbacterial thrombotic endocarditis induced by a hypobaric hypoxic environment in rats

 High-altitude hypoxia causes a hypercoagulable state. In our previous study on the blood coagulation system in rats, nonbacterial thrombotic endocarditis (NBTE) developed after 4–12 weeks’ exposure to the equivalent of 5500 m in altitude. We hypothesized that TF (tissue factor)-producing cells in the cardiac valves might be induced by the hypobaric hypoxic environment (HHE) and then trigger NBTE. A total of 170 male Wistar rats were housed in a chamber at the equivalent of 5500 m altitude for 1–12 weeks. We measured TF activity in the plasma and studied morphological changes in the mitral valves using immunohistochemical and immunoelectrical methods for TF protein and in situ hybridization for TF mRNA. After 4 weeks or more of exposure to HHE, 28 of the 56 surviving rats had developed NBTE. After 4–8 weeks’ exposure to HHE, the plasma TF activity level was significantly higher than in control rats. There was a significant correlation between plasma TF activity and the incidence of NBTE. After 1 weeks’ exposure to HHE, immunoreactivity for TF protein was detected in foamy macrophages and stromal cells in the cardiac valves. In rats with NBTE, TF protein was present in foamy macrophages and spindle stromal cells and focally present in the extracellular matrix. TF mRNA was detected in some foamy macrophages within the thrombus, TF protein was localized to the rough endoplasmic reticulum and plasma membrane of many macrophages, some fibroblasts, and a few endocardial cells. TF is associated with the pathogenesis of the NBTE induced by exposure to HHE. The accumulation of TF-producing macrophages during exposure to HHE may be responsible for initiating thrombus formation. Received: 6 March 1998 / Accepted: 30 April 1998     

Effects of carbon monoxide on responding under a progressive ratio schedule in rats

Under a progressive ratio schedule the response requirement increases arithmetically with each reinforcement, and the session is terminated when responding ceases for 15 min. Four rats, responding for food on this schedule, were exposed to 4 levels of carbon monoxide, ranging from 155 to 700 ppm, beginning 30 min before the test session and continuing throughout the session. The size of the last completed ratio and the local rate of responding decreased during exposure to the higher levels of carbon monoxide. Post reinforcement pause time was slightly increased for 3 of 4 rats during exposure to the highest level of CO.     

COPD合并慢性缺氧患者肺血管对急性缺氧反应变化中肺动脉平滑肌细胞钾通道的作用

目的：以人离体肺动脉环缺氧张力变化为对象研究钾通道在缺氧性肺血管收缩（HPV）发生中的作用。 方法： 从手术室切取人肺动脉环，进行人肺动脉环张力试验，分正常对照组，单纯慢性阻塞性肺病（chronic obstructive pulmonary disease ，COPD）组和COPD合并慢性缺氧组，分别利用相应的特异性阻断剂观察电压门控性钾通道（KV），钙离子激活的钾通道（KCa）， ATP敏感的钾通道（KATP），在缺氧性肺血管收缩（HPV）的作用。 结果： （1）3组肺动脉环在急性缺氧时血管收缩张力均增加，同时COPD＋慢性缺氧组增加百分比显著低于对照组；COPD组与对照组无显著差异。（2）4-AP阻断Kv后较阻断前，3组肺血管环缺氧张力增加幅度均显著降低（P<0.05），同时正常对照组和COPD组降低幅度明显大于慢性缺氧组。TEA阻断KCa后以及格列苯脲（glybenclamide）阻断KATP后二者较阻断前，3组肺血管环缺氧张力均显著增加（P<0.05），同时COPD＋慢性缺氧组增加的幅度明显大于正常组（分别是P<0.01和P<0.05）。 结论： （1）慢性缺氧可降低肺血管的收缩性及肺血管对急性缺氧的收缩反应；（2）Kv在3组人离体肺动脉环HPV反应中均起介导作用，慢性缺氧可使此介导作用加强；KCa和KATP在3组人离体肺动脉环HPV反应中均起调节作用，慢性缺氧可使此调节作用加强。     

ERK通路和三七总皂苷干预在低氧高二氧化碳性肺动脉高压中的作用

目的: 研究 ERK 信号通路在大鼠低氧高二氧化碳性肺动脉高压发生发展中的动态变化;探讨三七总皂苷(PNS)防治低氧高二氧化碳性肺动脉高压的机制。方法: 复制慢性低氧高二氧化碳性肺动脉高压大鼠模型;分为正常(N)组,低氧高二氧化碳性肺动脉高压3 d(H_3d)、1周(H_1w)、2周(H_2w)、4周(H_4w)组及PNS治疗(H_p)组,H_p组腹腔注射三七总皂甙注射液,余组注射等量生理盐水;光镜下比较各组大鼠肺细小动脉结构;Western 印迹法和免疫组织化学技术检测各组肺组织及肺血管 p-ERK、ERK 蛋白的表达。结果: (1) H_1w、H_2w、H_4w和H_p组的肺细小动脉管壁面积/管总面积(WA/TA) 均高于N组(均P<0.05), 但 H_3d 组较N 组增加不明显(P>0.05),H_p组 WA/TA 明显低于 H_4w 组(P<0.05)。 (2) 肺组织 p-ERK蛋白在 N 组表达不明显,在 H_3d 组表达即开始上升,在 H_1w、H_2w、H_4w 组均高水平表达 ( P<0.05)。 (3) 肺小动脉壁 p-ERK 蛋白在N组表达呈弱阳性或阴性,H_3d 组表达上升,在 H_1w、H_2w、H_4w 组表达水平逐渐升高( P<0.05)。(4) H_p组肺组织 p-ERK 蛋白、肺小动脉壁 p-ERK 蛋白表达较低氧高二氧化碳组降低(P＜0.05)。结论: ERK 信号通路可能介导了大鼠低氧高二氧化碳性肺动脉高压的形成。PNS 可能通过抑制p-ERK表达减轻这一过程。     

CO/HO体系影响缺氧性肺动脉高压幼年大鼠肺动脉超微结构的研究

目的 探讨血红素加氧酶，一氧化碳(HO/CO)体系对缺氧性肺动脉高压幼年大鼠肺动脉超微结构的影响。方法 将26只Wistar大鼠随机分为4组：对照组、低氧组、低氧 锌原卟啉(ZnPP)组和低氧 一氧化碳(CO)组。以右心导管法测定肺动脉压力，并对大鼠肺动脉进行超微结构观察。结果 低氧组大鼠肺动脉超微结构发生明显改变：内皮细胞呈柱状，部分核突入管腔，排列呈栅状，内皮细胞肿胀，胞浆内可见大量空泡，线粒体肿胀，内质网扩张；平滑肌细胞胞体肥大，胞浆中肌丝和致密斑减少。线粒体、粗面内质网和游离核糖体等三田胞器增多。约半数平滑肌细胞处于收缩表型，余呈过渡表型或合成表型，有肺血管结构重构形成。低氧 ZnPP组肺血管结构重建程度较低氧组加重：内皮细胞呈柱状，呈栅状排列，部分脱落致管腔，胞浆内可见大量空泡，线粒体肿胀，内质网扩张；平滑肌细胞形态不规则，胞体肥大，胞浆中肌丝和致密斑明显减少，粗面内质网和游离核糖体等细胞器明显增多。低氧组 CO组肺血管结构重建程度较低氧组减轻；内皮细胞胞体扁平，内衬血管内壁，其肿胀程度较低氧组减轻，空泡明显减少；平滑肌细胞改变较低氧组为轻，约半数平滑肌细胞处于收缩表型，余呈合成表型或过渡表型。结论 HO/CO系统对缺氧性肺动脉高压的形成以及缺氧性肺血管结构重建有重要的调节作用。     

Nitric oxide plays a minimal role in hypoxic pulmonary vasoconstriction in isolated rat lungs

The goal of this study was to elucidate the importance of nitric oxide production during hypoxic pulmonary vasoconstriction (HPV). One group of Sprague Dawley rats received an ip injection of saline (controls), while a second group received an ip injection of Escherichia coli lipopolysacharides (LPS-treated) to render them septic. Three hours later, the animals were anesthetized and prepared for the isolated lung experiment. The lungs were ventilated and perfused with diluted autologous blood (Hct 23%) at constant flow rate while monitoring pulmonary arterial pressure (Pa). Nitric oxide production from the lungs was monitored by measuring its concentration in the mixed exhaled gas (NOe) offline. NOe in the isolated lungs was 2 ppb in controls and 90 ppb in the LPS treated lungs. Hypoxia caused Pa to rise from 10 to 17 mmHg in control lungs, and from 10 to 27 mmHg in the LPS treated lungs. NO production was then manipulated to determine if it affects HPV. NOe was increased by adding l-arginine to the blood, and was blocked by adding nitro-l-arginine (LNA). l-Arginine had minimal effect on NOe in control lungs, but increased NOe in LPS treated lungs, and yet HPV was similar in the 2 groups. Despite inhibition of NO synthesis with nitro-l-arginine (LNA), HPV was potentiated equally in control and in LPS treated lungs (Pa rose by 23 mmHg). Thus NO production did not affect the difference in HPV between control and LPS treated lungs. The results suggest that NO does not plays a primary role in HPV.     

The direct effect of carbon monoxide on KCa channels in vascular smooth muscle cells

 The vasorelaxation induced by carbon monoxide (CO) has been demonstrated previously. Both a guanosine cyclic monophosphate (cGMP) signalling pathway and cGMP-independent mechanisms have been proposed to be responsible for the vascular action of CO. A direct effect of CO on the activity of calcium-activated K (K_Ca) channels in vascular smooth muscle cells (SMCs) and the underlying mechanisms were investigated in the present study. It was found that CO hyperpolarized single SMCs isolated from rat tail arteries. The whole-cell outward K⁺ channel currents in vascular SMCs, but not in neuroblastoma cells, were enhanced by CO. Extracellularly or intracellularly applied CO increased the open probability of single high-conductance K_Ca channels concentration-dependently without affecting the single channel conductance. Although it did not increase the resting level of intracellular free calcium concentration, CO significantly enhanced the calcium sensitivity of single K_Ca channels in SMCs. Furthermore, the effect of CO on K_Ca channels was not mediated by cGMP or guanine nucleotide-binding proteins (G proteins, G_i/G_o or G_s) in excised membrane patches. Our results suggest that the direct modulation of high-conductance K_Ca channels in vascular SMCs by CO may constitute a novel mechanism for the vascular effect of CO. Received: 9 January 1997 / Received after revision: 21 February 1997 / Accepted: 10 March 1997     

一氧化碳对低氧性肺动脉高压的效应

目的:探讨外源性低浓度一氧化碳(CO)在低氧性肺动脉高压中的作用。方法:60只Wistar大鼠随机分为常氧组、低氧组、血晶素组、锡原卟啉组和低浓度CO组,每组12只。处理完毕后,右心导管法测定肺动脉平均收缩压和右心室压。杀鼠取肺组织,应用分光光度法测定肺组织HO-1活性,并进行常规免疫组织化学染色,应用逆转录多聚酶链式反应测定测定肺组织的HOmRNA水平。结果:①低浓度CO组肺动脉压为(18.52±3.24)mmHg,明显低于低氧组但仍高于常氧组(均为P＜0.01);②低浓度CO组HO-1活性为(1052.48±308.49)nmol·g^-1(protein),显著高于正常组(P＜0.01);③低浓度CO组HO-1蛋白表达水平均高于常氧组和低氧组(P＜0.01);④低浓度CO组HO-1mRNA水平的光密度值为2.63±0.18,显著高于正常组(P＜0.01)。结论:CO-HO系统参与了低氧性肺动脉高压的发病机制;低浓度CO可以有效促进HO-1mRNA表达,使HO-1活性和蛋白表达水平升高,进而部分降低肺动脉压力。     

一氧化碳对大鼠血管平滑肌细胞低氧性增殖反应的作用

目的：观察低氧时大鼠肺动脉平滑肌细胞（ＰＡＳＭＣ）受血管舒张因子一氧化碳的作用。方法：随机分为常氧组、低氧组（１％Ｏ２＋５％ＣＯ２＋９４％Ｎ２）、一氧化碳组（３％ＣＯ＋５％ＣＯ２＋９２％Ｎ２）,采用流式细胞仪、增殖细胞抗原（ＰＣＮＡ）、「６３Ｈ」－胸腺嘧啶「＾３Ｈ」－ＴｄＲ摄取量,检测ＰＡＳＭＣ增生的情况。结果：（１）流式细胞仪检测低氧组ＰＡＳＭＣＣ２／Ｍ期细胞比例明显增多,Ｇ０／Ｇ１期细胞比例明     

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。     

Pinacidil对低氧性肺动脉高压大鼠肺动脉压和血浆内皮素-1的影响

目的：探讨钾通道开放剂pinacidil对低氧性肺动脉高压（HPH）及对血浆内皮素-1（ET-1）含量的影响。方法：将45只雄性Wistar大鼠分为3组：①对照组;②低氧组,每天低氧8 h,共4周;③治疗组,每天低氧前半小时腹腔注射pinacidil 3 mg/kg,共4周,4周后观察3组平均肺动脉压（mPAP）,右心室肥厚指标、血浆中ET-1的水平。结果：低氧组大鼠mPAP明显高于对照组。右心室肥厚显著,血浆中ET-1含量明显高于对照组;治疗组mPAP明显低于低氧组,右心室肥厚轻于低氧组,血浆中ET-1含量明显低于低氧组。结论：pinacidil能有效降低HPH中肺动脉压力、阻抑右心室肥厚,并影响血浆中ET-1的水平。