Oral pre‐treatment with rosuvastatin protects porcine myocardium from ischaemia/reperfusion injury via a mechanism related to nitric oxide but not to serum cholesterol level

Aims: The aim of this study was to test whether oral pre‐treatment with rosuvastatin at a dosage giving clinically relevant plasma concentrations protects the myocardium against ischaemia/reperfusion injury and to investigate the involvement of nitric oxide (NO) and neutrophil infiltration. Methods: Pigs were given placebo (n = 7), rosuvastatin (80 mg day^?1, n =7), rosuvastatin (160 mg day^?1, n = 7) or pravastatin (160 mg day^?1, n = 7) orally for 5 days before being subjected to coronary artery ligation and reperfusion. An additional group was given rosuvastatin 160 mg day^?1 and a nitric oxide synthase (NOS) inhibitor. Results: Rosuvastatin 80 and 160 mg day^?1 resulted in plasma concentrations of 2.6 ± 0.7 and 5.6 ± 1.0 ng mL^?1, respectively. Serum cholesterol was not affected. Rosuvastatin 160 mg day^?1 and pravastatin limited the infarct size from 82 ± 3% of the area at risk in the placebo group to 61 ± 3% (P < 0.05), and to 61 ± 2% (P < 0.05) respectively. Rosuvastatin 80 mg day^?1 limited the infarct size to 69 ± 2%, however, this effect was not statistically significant. Rosuvastatin 160 mg day^?1 attenuated neutrophil infiltration in the ischaemic/reperfused myocardium. The protective effect of rosuvastatin 160 mg day^?1 was abolished by NOS inhibition. The expression of NOS2 and NOS3 in the myocardium did not differ between the groups. Conclusions: Oral pre‐treatment with rosuvastatin limited infarct size following ischaemia/reperfusion without affecting cholesterol levels. The cardioprotective effect is suggested to be dependent on maintained bioactivity of NO, without influencing NOS expression.     

Endogenous nitric oxide as a probable modulator of pulmonary circulation and hypoxic pressor response in vivo

The objective of this study was to investigate the role of endogenous nitric oxide, formed from L-arginine, in the regulation of pulmonary circulation in vivo, with special reference to the hypoxic pressor response. In artificially ventilated open-chest rabbits, pulmonary vascular resistance at normoxic ventilation (F₁₀₂= 21 %) was 78C 16 cmH₂O ml^-l min 1000^-1 (mRU_L). Hypoxic ventilation (F₁₀₂= 10%) increased pulmonary vascular resistance to 117 ± 17 mRU_L. N^w-nitro-L-arginine methylester (L-NAME), an inhibitor of nitric oxide synthase, increased pulmonary vascular resistance at normoxic ventilation to 192 ± 28 mRU_L and during hypoxic ventilation to 462 ± 80 mRU_L. During N^w-nitro-l-arginine methylester infusion there was also an increase in mean arterial blood pressure as well as a decrease in cardiac output that was even more pronounced during hypoxic ventilation. L-arginine reversed the effect of N^w-nitro-l-arginine methylester on pulmonary vascular resistance at normoxic ventilation to 140 ± 26 mRU_L and at hypoxic ventilation to 239 ± 42 mRU_L. In spontaneously breathing closed-chest rabbits, N^w-nitro-L-arginine methylester evoked a marked decrease in arterial P_o2, and increases in respiration frequency and central venous pressure, while blood pH, P_CO2 and base excess remained unchanged. Taken together these findings indicate that endogenous nitric oxide, formed from L-arginine, might be a regulator of ventilation-perfusion matching at normoxic ventilation, and that nitric oxide acts as an endogenous modulator of the hypoxic pressor response.     

Oxygen or low concentrations of nitric oxide reverse pulmonary vasoconstriction induced by nitric oxide synthesis inhibition in rabbits

The objective of this study was to investigate the role of nitric oxide and oxygen in the regulation of pulmonary vascular resistance, especially by means of substitution with nitric oxide after inhibition of endogenous nitric oxide formation. In artificially ventilated open-chest rabbits pulmonary vascular resistance at normoxic ventilation (F₁0₂= 21%) was 56±6cmH₂O ml^-1 mim-¹ 1000^-1 (mRU_L). N^w-nitro-L-arginine methyl ester (l-NAME, 30 mg kg^-1), an inhibitor of NO synthase, increased pulmonary vascular resistance to 122±17 mRU_L at normoxic ventilation. In response to l-NAME there was also an increase in mean arterial blood pressure. Exogenous nitric oxide (0.014-9 p.p.m. in the inhaled air) dose-dependently and reversibly counteracted the effect of l-NAME on pulmonary vascular resistance at normoxic ventilation, without affecting systemic blood pressure. In addition, the L-NAME-induced vasoconstriction was critically dependent on oxygen. Thus, during hypoxic ventilation (F₁O₂= 10%) the pulmonary vascular resistance was increased approximately four-fold by the presence of L-NAME (30 mg kg^-1), and increments in F,0₂ (21–100%) dose-dependently and reversibly counteracted the effect of L-NAME on pulmonary vascular resistance. Taken together these findings demonstrate that inhalation of low doses of NO may act as a replacement when endogenous NO synthesis is inhibited, and that pulmonary vasoconstriction induced by NO synthesis inhibition is likely to be the result of interference with oxygen-dependent regulatory mechanisms. Endogenous NO cooperates with oxygen to evoke a vasodilator component of the pulmonary hypoxic pressor response, balancing a hitherto unknown constrictor mechanism.     

Modulation of vascular tone and reactivity by nitric oxide in porcine pulmonary arteries and veins

Isolated porcine pulmonary vessels were studied in order to evaluate the role of nitric oxide in arteries and veins. Leukotriene C4 and noradrenaline contracted porcine pulmonary arteries but induced only negligible contractions of porcine pulmonary veins. After treatment with the nitric oxide synthase inhibitor N(omega)-nitro-L-arginine (L-NOARG), significant contractions to leukotriene C4 and noradrenaline were uncovered in pulmonary veins. In arterial preparations, L-NOARG caused a less marked potentiation of noradrenaline-induced contractions and did not alter leukotriene C4-induced contractions. Endothelium-dependent relaxations to acetylcholine were greater in veins compared with arteries whereas the endothelium-independent relaxations to the nitric oxide donor sodium nitroprusside (SNP) and the cyclic nucleotide analogue 8-bromo-cGMP were similar in the two preparations. Taken together these data suggest that the apparent insensitivity of porcine pulmonary veins to leukotriene C4 and noradrenaline was because of release of nitric oxide. The effect of nitric oxide synthase inhibition was less pronounced in porcine pulmonary arteries, suggesting a preferential functional role of nitric oxide in porcine pulmonary veins, originating in a greater production of nitric oxide by veins as opposed to arteries.     

Effect of adenovirus-mediated gene transfer of nitric oxide synthase on vascular reactivity of rat isolated pulmonary arteries

Aerosol gene transfer of endothelial nitric oxide synthase (eNOS) and inducible NOS (iNOS) to rat lungs increased NOS expression and activity, and prevented hypoxic pulmonary vasoconstriction (HPV) in vivo. Hereby, we examined the effect of eNOS and iNOS aerosol gene transfer on the endothelium-dependent relaxation (EDR) and on acute HPV in isolated rat pulmonary arteries. Changes in isometric forces were recorded in organ baths for large conduit arteries (diameter 1.8±0.1 mm) and in a wire myograph for small resistance arteries (258±35 μm). Male Wistar rats were randomly aerosolized with adenovirus (Ad) encoding β-galactosidase (control), eNOS, or iNOS. Four days later, exhaled nitric oxide was measured, NOS expression within rat lungs was evaluated by quantitative real-time polymerase chain reaction and immunohistochemistry, vasoconstricting agonist and acetylcholine concentration response curves were generated, and the time course of HPV was recorded. Human eNOS and murine iNOS were expressed within rat lung tissue mostly in parenchyma and endothelial cells. Large arteries isolated from Ad-i, eNOS-aerosolized rats developed lower agonist-induced tension than those of control rats. The first and second contractions of the HPV were smaller in the Ad-i, eNOS-aerosolized rats. Contractions were modestly, but significantly and inversely, related to exhaled NO. Agonist- and hypoxia-induced contractions were even more reduced after eNOS aerosolization. There was no significant effect on EDR and no notable difference between small and large vessels. We conclude that adenovirus (Ad)-mediated NOS gene transfer can counteract both pharmacologically and hypoxia-induced increases in pulmonary vascular tone in isolated rat pulmonary arteries. eNOS seems as efficient as iNOS in regulating pulmonary vascular tone.     

Prostacyclin aerosol and inhaled nitric oxide fail to reverse pulmonary vasoconstriction induced by thromboxane analogue in dogs

Inhalation of either prostacyclin (PGI₂) as an aerosol or nitric oxide (NO) has been shown to elicit selective pulmonary vasodilation during hypoxic pulmonary vasoconstriction in dogs. Hypoxia may produce cardiovascular changes confounding interpretation of drug effects. Therefore, we investigated the effects of PGI₂-aerosol and inhaled NO (50 p.p.m.) on pulmonary pressure-flow relationships (P/Q_ plots) during thromboxane analogue (U46619) induced pulmonary vasoconstriction. In eight anaesthetized dogs infusion of U46619 (0.33 ± 0.18 μg kg_¹ min^-1) increased the slope (3.5 ± 1.1 to 8.4 ± 1.7 mmHg L^-1 min^-1, P < 0.001) and the intercept (4.4±2.3 to 10.2 ± 4.6 mmHg, P < 0.01) of P/Q plots indicating pulmonary vasoconstriction. Inhalation of both aerosolized PGI₂ solution (10μgmL^-1) and NO (50 p.p.m.) reduced neither the slope nor the intercept of the P/Q_ plots. Increasing the concentration of the aerosolized PGI₂ solution to 50 μg mL^-1: (n= 3) did not enhance the effect on pulmonary circulation but systemic vascular resistance fell by 23%. Oxygenation and intrapulmonary shunt remained unchanged during both PGI₂-aerosol and inhaled NO. The failure of PGI₂-aerosol to induce pulmonary vasodilation indicates that during aerosolization PGI₂-concentrations at receptor sites on pulmonary vessels were insufficient to surmount U46619 induced vasoconstriction; this notion is supported by unchanged arterial plasma concentrations of the PGI₂ degradation product 6-keto-PGF_lα. Considering that NO inhaled at comparable concentrations in sheep reversed U46619 induced pulmonary vasoconstriction, species differences may account for the failure of both PGI₂-aerosol and NO to dilate pulmonary vessels in dogs.     

Effect of fetal anaemia on myocardial ischaemia-reperfusion injury and coronary vasoreactivity in adult sheep

Aims: We investigated whether chronic fetal anaemia affects myocardial infarct in adulthood and elicits functional modifications in adult coronary vasoreactivity. Methods: Seven‐month‐old sheep that were made anaemic in utero and transfused to normal haematocrit before birth were studied. Infarct size was determined by tetrazolium after 1‐h ischaemia (occlusion of the mid of left anterior descending artery) and 2‐h reperfusion. The dose–response to vasoconstrictors and vasodilators was assessed in small resistance coronary arteries. Results: There were no significant differences between the animals previously subjected to in utero anaemia and the control animals regarding the percentage infarct size and the area‐at‐risk to the left ventricle. The ventricular function (dP/dt) was preserved. The percentage infarct size of the area‐at‐risk (70.7 ± 3.5%) was larger than that in the controls (49.8 ± 4.5%) (P = 0.006). The vascular responses were not altered. Endothelium‐dependent relaxation to bradykinin (96.0 ± 2.6% vs. 98.8 ± 1.0%) was not affected by PGI₂ inhibitor (94.6 ± 2.6% vs. 98.5 ± 1.0%) but significantly reduced by the inhibition of nitric oxide (NO) in both anaemic (P < 0.05) and control (P < 0.001) groups with a significant right shift of EC₅₀ (P < 0.01). The non‐NO–non‐PGI₂‐mediated relaxation was slightly potentiated in anaemic animals. Conclusions: Exposing fetal sheep to in utero anaemia in late gestation for 3 weeks may increase the susceptibility of adult hearts to ischaemia–reperfusion injury without major alterations in coronary vasomotor responsiveness. The impact of in utero anaemia at earlier period of pregnancy and on the earlier or later life of the adult is yet to be further investigated.     

急性缺氧大鼠血浆、呼出气NO含量的变化及吸入NO对缺氧性肺血管收缩的影响

观察了大鼠急性缺氧前后血浆和呼出气一氧化氮（ＮＯ）含量的变化，结果显示，动物吸人１０％，２０ｍｉｎ后，血浆ＮＯ＿２／ＮＯ＿３浓度从２３．５６±７．１３升至４１．６３±１０．１０μｍｏｌ／Ｌ（Ｐ＜０．０１）；呼出气ＮＯ浓度出０．０９９±０．０５５增至０．１６２±０．１０８ｐｐｍ（Ｐ＜０．０１）．提示急性缺氧时ＮＯ生成增多可能在缺氮性肺血管收缩（ＨＰＶ）中起调节作用。为探讨吸入ＮＯ对ＨＰＶ的影响，本文采用人工呼吸给缺氧大鼠吸入４０ｐｐｍＮＯ，发现动物缺氧（１０％Ｏ＿２）１０ｍｉｎ后，平均肺动脉压（ｍＰＡＰ）和肺血管阻力（ＰＶＲ）较基础值明显升高（Ｐ＜０．０１）：而缺氧同时吸入４０ｐｐｍＮＯ１０ｍｉｎ，ｍＰＡＰ和ＰＶＲ较缺氧时明显降低（Ｐ＜０．０１），与基础值无显著差别（Ｐ＞０．０５），且发现△ＰＶＲ％为２．９４±９．８５％，较缺氧时６６．１８±２３．３９％明显降低（Ｐ＜０．０１），但吸入ＮＯ对体动脉压、体血管阻力，心输出量、血气和高铁血红蛋白无明显影响。从而提示吸入ＮＯ选择性降低缺氧性肺动脉高压且完全逆转ＨＰＶ。     

Endogenous nitric oxide as a probable modulator of pulmonary circulation and hypoxic pressor response in vivo.

The objective of this study was to investigate the role of endogenous nitric oxide, formed from L-arginine, in the regulation of pulmonary circulation in vivo, with special reference to the hypoxic pressor response. In artificially ventilated open-chest rabbits, pulmonary vascular resistance at normoxic ventilation (FIO2 = 21%) was 78 +/- 16 cmH2O ml-1 min 1000-1 (mRUL). Hypoxic ventilation (FIO2 = 10%) increased pulmonary vascular resistance to 117 +/- 17 mRUL. N omega-nitro-L-arginine methylester (L-NAME), an inhibitor of nitric oxide synthase, increased pulmonary vascular resistance at normoxic ventilation to 192 +/- 28 mRUL and during hypoxic ventilation to 462 +/- 80 mRUL. During N omega-nitro-L-arginine methylester infusion there was also an increase in mean arterial blood pressure as well as a decrease in cardiac output that was even more pronounced during hypoxic ventilation. L-arginine reversed the effect of N omega-nitro-L-arginine methylester on pulmonary vascular resistance at normoxic ventilation to 140 +/- 26 mRUL and at hypoxic ventilation to 239 +/- 42 mRUL. In spontaneously breathing closed-chest rabbits, N omega-nitro-L-arginine methylester evoked a marked decrease in arterial PO2 and increases in respiration frequency and central venous pressure, while blood pH, PCO2 and base excess remained unchanged. Taken together these findings indicate that endogenous nitric oxide, formed from L-arginine, might be a regulator of ventilation-perfusion matching at normoxic ventilation, and that nitric oxide acts as an endogenous modulator of the hypoxic pressor response.     

吸入一氧化氮对婴幼儿体外循环中肺功能的影响

目的探讨吸入一氧化氮（Nitric oxide,NO）对婴幼儿体外循环手术中肺功能的影响。方法将30例患室间隔缺损的婴幼儿随机分为对照组和NO组,NO组在体外循环期间吸入40 ppm NO直至关胸。体外循环前和术后气管插管未拔前0-1h、1-2h、2-3h测定气道压、吸入氧浓度和呼气末二氧化碳浓度（ETCO2）,并分别在同时点采动脉血进行血气分析,计算肺泡死腔率（VD/VT）肺、泡动脉血氧分压差（P（A-a）O2）、动脉血氧含量（CaO2）和肺泡氧合指数（OI）,记录术后呼吸机支持时间。体外循环前、主动脉开放后1、5、10min分别取右上肺静脉血和右心房血用于测定丙二醛（MDA）、超氧化物歧化酶（SOD）。结果与NO组相比,对照组再灌注后VD/VT、P（A-a）O2,OI明显升高（P〈0.05）,CaO2下降（P〈0.01）;MDA明显升高（P〈0.05）;SOD明显降低（P〈0.01）。结论婴幼儿体外循环术中存在明显肺损害,表现为一些亚临床性肺功能损伤。吸入40 ppm NO对体外循环期间肺功能有保护作用。     

前列腺素、一氧化氮和钾通道在鼠兔缺氧肺血管反应钝化中的作用

目的:探索前列腺素、一氧化氮和电压依赖性钾通道在高原动物鼠兔的缺氧性肺血管收缩反应钝化中的作用。方法:用鼠兔肺组织条替代肺血管进行实验,并以Wistar鼠肺组织条作为对照组。分别观察环加氧酶(cyclooxygenase,COX)抑制剂吲哚美辛(indomethacin)、一氧化氮合酶(nitricoxidesynthase,NOS)阻断剂L-NAME、电压门控的钾通道的阻断剂4-AP,对缺氧性肺血管收缩反应的影响。结果:(1)吲哚美辛组:吲哚美辛使鼠兔肺组织条的缺氧张力升高平均值比用吲哚美辛前增加64.7%;Wistar鼠肺组织条仅增加19.7%;两组差异显著,P＜0.05;(2)L-NAME组:L-NAME使鼠兔肺组织条缺氧性张力升高平均值增加102.7%;Wistar鼠肺组织条仅增加60.7%;两组差异显著,P＜0.05;(3)4-AP组:4-AP使鼠兔肺组织条缺氧张力平均值降低43.8%;Wistar鼠肺组织条降低28.53%;两组无显著差异,P＞0.05。结论:(1)NO和前列腺素在肺血管缺氧收缩反应中可能起调节作用,而电压门控的钾通道可能起介导作用;(2)鼠兔肺血管对缺氧收缩反应性钝化的机制中NO和前列腺素可能起更重要的介导作用,而电压门控的钾通道可能不起重要作用。     

一氧化氮吸入对缺氧性肺动脉高压患者一氧化氮合酶和内皮素-1的影响

目的: 探讨吸入一氧化氮(NO)对缺氧性肺动脉高压患者一氧化氮合酶(NOS)和内皮素-1(ET-1)的影响。方法: 13例肺动脉高压患者行NO吸入,分别于吸入NO前、吸入30 min时、停止吸入2 h和12 h采肺动脉血,测白细胞中的NOS及血浆中的ET-1。结果: 吸入NO前、吸入30 min时、停止吸入2 h和12 h,所测NOS值分别为(0.70±0.21)mol/min·mg^-1、(0.74±0.14)mol/min·mg^-1、(0.64±0.22)mol/min·mg^-1和(0.63±0.17)mol/min·mg^-1;所测ET-1为(78.89±46.59)pmol/L、(88.27±45.41)pmol/L、(80.76±42.66)pmol/L和(61.07±29.44)pmol/L;后三者同吸入前比,P均＞0.05。结论: 缺氧性肺动脉高压患者吸入NO对机体NOS和ET-1未见明显影响。     

慢性低氧性肺动脉高压大鼠内源性一氧化氮代谢及其外源性吸入的研究

目的:研究一氧化氮(NO)在大鼠慢性低氧性肺动脉高压发生发展中的代谢变化,观察外源性吸入NO对肺血流动力学的疗效。方法:67只SD雄性成年大鼠,随机分为7组:常氧对照组(n=9),慢性间断性低氧(6h/d,7d/周)1周组(n=7),低氧2周组(n=11),低氧3周组(n=11),L-NAME(NO合成酶抑制剂,30mg/kg,灌饲)处理组(n=10),L-Arg(NO合成前质,10mg/kg,灌饲)处理组(n=9),NO吸入(0.0004%,20min)组(n=10)。插管测肺动脉平均压(MPAP),分离右心室(R)、室间膈+左心室(S+L),计算R/(S+L)(g/g)和R/Wt(Wt:体重,g/kg)。结果:①低氧1周组MPAP显著高于对照组,低氧2周时更高,R/(S+L)和R/Wt也显著高于对照组;②血浆NO₂^-/NO₃^-含量在低氧2周组显著高于对照组,而在低氧3周组显著低于低氧2周组和低氧1周组;低氧1周,血浆ET-1含量显著高于对照组,血浆ET-1含量与MPAP和R/(S+L)均呈显著正相关,r分别为0.43和0.46,P值均＜0.01;③L-NAME组大鼠血浆NO₂^-/NO₃^-含量降低33.2%,R/(S+L)显著增加15.2%,P＜0.05;④L-Arg组大鼠血浆NO₂^-/NO₃^-含量和PAPM无显著改变,但R/(S+L)降低8.7%,P＜0.05;⑤吸入NO,MPAP降低17.8%,P＜0.01。结论:内源性NO在慢性低氧早期(1-2周)继发性增加,但进一步低氧时则减少,血浆ET-1含量的增加在低氧性心肺血管重建中可能具有重要意义,吸入低浓度NO对以肺血管增生和右心室肥大为主要基础的肺动脉高压仍具有明显降低作用。     

Endogenous nitric oxide and pulmonary circulation response to hypoxia in high-altitude adapted Tibetan sheep

Nitric oxide (NO) is important for the pulmonary circulation response to acute and chronic hypoxia. We examined effects of endogenous nitric oxide synthase (NOS) inhibition on pulmonary vascular tone in response to hypoxia in Tibetan sheep dwelling at 3,000 m above sea level using a pressure chamber. Unanaesthetized male sheep living at 2,300 m above sea level (n=7) were prepared for vascular monitoring. Pulmonary artery (P_pa), pulmonary artery wedge (P_cwp) and systemic artery pressures together with cardiac output (CO) were measured, and pulmonary vascular resistance (PVR) was calculated as (P_pa–P_cwp)/CO. A non-selective NOS inhibitor, N-nitro-l-arginine (NLA; 20 mg kg^–1), and a selective NOS inhibitor, ONO-1714 (0.1 mg kg^–1), were used and measurements were made at 0 m, 2,300 m, and 4,500 m, with and without the NOS inhibitors. After NLA, P_pa increased slightly and CO decreased in animals at baseline (2,300 m). The increased PVR after NLA at 4,500 m was greater than that at 2,300 m (P<0.05). Selective NOS inhibition increased PVR at baseline, but not at 4,500 m. The enhanced pulmonary vasoconstriction after NO inhibition at basal and hypoxic conditions suggests a modulating role of NOS bioactivity in the pulmonary circulation and that augmented endothelial NOS plays a counterregulatory role in the pulmonary vasoconstrictor response to acute hypoxia in high-altitude adapted Tibetan sheep.     

NF-κB的活性和iNOS基因表达在低氧性肺动脉高压中的变化

目的：探讨NF-κB的活性及iNOS基因表达在低氧性肺动脉高压（HPH）发病过程中的变化。方法：复制低氧性肺动脉高压大鼠模型，用免疫组化、原位杂交、半定量逆转录-聚合酶链式反应（RT-PCR）和Western blot等方法进行检测。结果：iNOS mRNA在腺泡内肺动脉（IAPA）的表达，低氧28 d（H28d）组染色强于正常（N）组、低氧5 d（H5d）组和低氧14 d（H14d）组。半定量RT-PCR证实低氧肺组织iNOS mRNA含量在H28d组分别是N组、H5d组和H14d组的2.1倍、1.9倍和1.8倍。H28d组肺组织NF-κB的核染色增多，I-κBα的含量在N组、H5d组和H14d组分别是H28d组的2.7倍、2.8倍和2.5倍。结论：在HPH中NF-κB的激活可能与低氧肺血管构建及iNOS mRNA的表达有关。     

缺氧性肺动脉高压时一氧化氮合酶、左旋精氨酸及亚硝基左旋精氨酸甲酯的研究

目的研究一氧化氮（ＮＯ）在缺氧性肺动脉高压（ＨＰＨ）发病中的作用。方法用烟酰胺腺嘌呤二核苷酸磷酸—黄递酶（ＮｉｃｏｔｉｎａｍｉｄｅＡｄｅｎｉｎｅＤｉｎｕｃｌｅｏｔｉｄｅＰｈｏｓｐｈａｔｅＤｉａｐｈｏｒａｓｅ，ＮＡＤＰＨｄ）和免疫组化ＡＢＣ方法检测原生型和诱生型一氧化氮合酶（ｃＮＯＳ、ｉＮＯＳ）在正常和缺氧大鼠肺内的表达和分布，同时观察左旋精氨酸（Ｌａｒｇ）和亚硝基左旋精氨甲酯（ＬＮＡＭＥ）对正常和缺氧大鼠肺循环的影响。结果ＨＰＨ组，ＮＡＤＰＨｄ阳性反应见于大血管内皮、平滑肌、支气管粘膜上皮及小血管内皮和平滑肌中，而后者在正常时未见阳性反应；ｃＮＯＳ在肺血管内皮和支气管粘膜上皮中的表达明显减弱，甚至消失，而正常时不表达ｉＮＯＳ的肺血管内皮和血管、支气管平滑肌在ＨＰＨ组出现了阳性表达；缺氧时补充Ｌａｒｇ和ＬＮＡＭＥ，与单纯缺氧相比，对右心室肥大和肺血管重建无影响。结论缺氧时ｃＮＯＳ被抑制，可能对ＨＰＨ的形成具有一定的作用；而ｉＮＯＳ的诱导表达，则可能对ＨＰＨ的形成具有阻止作用。     

Effects of sevoflurane and propofol on right ventricular function and pulmonary circulation in patients undergone esophagectomy

Object: Sevoflurane and propofol are both widely used in clinical anesthesia. The aim of this study is to compare the effects of sevoflurane and propofol on right ventricular function and pulmonary circulation in patients receiving esophagectomy. Methods: Forty adult patients undergoing an elective open-chest thoracotomy for esophagectomy were randomized to receive either propofol (n=20) or sevoflurane (n=20) as the main anesthetic agent. The study was performed in Changzheng Hospital. Hemodynamic data were recorded at specific intervals: before the surgery (T0), BIS values reaching 40 after anesthesia induction (T1), two-lung ventilation (T2), ten minutes after one-lung ventilation (T3), the end of the operation (T4) using PiCCO₂ and Swan-Ganz catheter. Results: CI, RVEF, RVSWI and RVEDVI were significantly smaller in propofol group than those in sevoflurane group throughout the surgery (P<0.05). However, SVRI was significantly greater in propofol group than that in sevoflurane group (P<0.05). Compared with the patients in propofol group, the patients who received sevoflurane had a greater reduction in OI and increase in Os/Ot (P<0.05). And, PVRI was significantly smaller in sevoflurane group than in propofol group (P<0.05). Conclusion: Anesthesia with sevoflurane preserved better right ventricular function than propofol in patients receiving esophagectomy. However, propofol improved oxygenation and shunt fraction during one-lung ventilation compared with sevoflurane anesthesia. To have the best effect, anesthesiologists can choose the two anesthetics flexibly according to the monitoring results.     

Responses of the bronchial and pulmonary circulations to short‐term nitric oxide inhalation before and after endotoxaemia in the pig

The physiological responses of the bronchial circulation to acute lung injury and endotoxin shock are largely unexplored territory. This study was carried out to study the responsiveness of the bronchial circulation to nitric oxide (NO) inhalation before and after endotoxaemia, in comparison with the pulmonary circulation, as well as to study changes in bronchial blood flow during endotoxaemia. Six anaesthetized pigs (pre‐treated with the cortisol‐synthesis inhibitor metyrapone) received an infusion of 10 µg/kg endotoxin during 2 h. Absolute bronchial blood flow was measured via an ultrasonic flow probe around the bronchial artery. The pigs received increasing doses of inhaled NO over 5 min each (0, 0.2, 2 and 20 ppm) before and after 4 h of endotoxaemia. The increase in bronchial vascular conductance during 5 min of inhalation of 20 ppm NO before endotoxin shock was significantly higher (area under curve (AUC) 474.2 ± 84.5% change) than after endotoxin shock (AUC 118.2 ± 40.4%, P < 0.05 Mann–Whitney U‐test). The reduction of the pulmonary arterial pressure by 20 ppm NO was not different. A short rebound effect of the pulmonary arterial pressure occurred after discontinuation of inhaled NO before endotoxaemia (AUC values above baseline 54.4 ± 19.7% change), and was virtually abolished after endotoxaemia (AUC 6.1 ± 4.0%, P = 0.052, Mann–Whitney U‐test). Our results indicate that the responsiveness of the bronchial circulation to inhalation of increasing doses of inhaled NO during endotoxin shock clearly differ from the responsiveness of the pulmonary circulation. The reduced responsiveness of the bronchial circulation is probably related to decreased driving pressure for the bronchial blood flow. The absence of the short rebound effect on pulmonary arterial pressure (PAP) after induction of shock could be related to maximum constriction of the pulmonary vessels at 4 h.