内皮素-1、一氧化氮、一氧化氮合酶、B型内皮肽受体及移动抑制因子在大鼠肝肺综合征作用中的初步研究

目的 探讨内皮素-1（ET-1）、内皮素B（ETB）受体、NOS、NO及巨噬细胞游走抑制因子（MIF）在大鼠肝肺综合征（HPS）作用中的机制.方法 将雄性Wistar大鼠共48只随机分为正常对照组（Control组）、胆总管结扎组（CBDL组）、肝前门静脉高压组（PVL组）及CBDL＋抗MIF组四组.分别对Control组和PVL组术后5周,以及CBDL组和CBDL＋抗MIF组术后2周、3周和5周进行：门静脉压力、血气分析、肝功能以及血清NO、ET-1、肺组织内ETB受体、一氧化氮合酶诱导型（iN-OS）、一氧化氮合酶内皮型（eNOS）蛋白表达及MIF水平进行检测,检查肝、肺病理,并使用激光多普勒血流仪检测肝、肺微循环差异.结果 CBDL组和Control组相比肝功能检测中白蛋白降低,胆红素、AST均升高;血气分析中PaO2降低,AaPO2增大;肝脏毛细血管血流量降低（P＜0.05）;肺脏毛细血管血流量增大（P＜0.05）;血浆内ET-1、NO及MIF水平增高;肺脏组织内eNOS、ETB受体蛋白表达增高（P＜0.05）;且病理检查CBDL组大鼠的肝脏组织可见胆汁性纤维化表现,肺组织可见肺毛细血管扩张、充血,证实HPS大鼠模型制成.PVL组大鼠与Control组相比,除门静脉压力和组织内ETB受体蛋白表达增高外（P＜0.05）,其余指标的差异无统计学意义.CBDL＋抗MIF组在各项指标及病理检测中,血浆内ET-1、NO及MIF水平较CBDL组相比有所降低,肝、肺病理变化较CBDL组减轻.肺脏组织内iNOS蛋白表达在四组间的表达差异无统计学意义.结论 在CBDL建立的HPS大鼠模型中,可能是ET-1可被肝脏过量生成,进入血液循环,与肺脏血管内皮细胞上的ETB受体结合,增加eNOS的表达和活性,NO产生增多,引起肺内血管扩张,进一步引起HPS,抗MIF抗体通过抑制MIF在对抗CBDL引起HPS的发生中发挥一定的作用.     

参附对失血性休克大鼠肺脏组织中内皮细胞蛋白C受体表达的影响

目的:观察参附对失血性休克大鼠肺脏组织中内皮细胞蛋白C受体(EPCR)表达的影响和意义。方法:104只SD大鼠随机分为正常组、假休克组、失血性休克组、林格液组、参附注射液组。采用RT-PCR方法检测失血性休克及药物复苏大鼠不同时间点肺脏组织中血管EPCR的动态变化。结果:失血性休克组肺脏组织中EPCRmRNA明显升高,林格液组和参附注射组早期有所升高,随后开始下降。与失血性休克组相比,林格液组和参附注射液组肺内EPCRmRNA含量均明显降低,差异有统计学意义,且参附注射组下降更明显。结论:参附注射液能减少失血性休克大鼠肺脏组织中EPCR的表达,改善失血性休克大鼠凝血功能,而早期应用效果可能更好。     

Inhibition of nitric oxide synthesis by L-name exacerbates acute lung injury induced by hepatic ischemia-reperfusion.

Hepatic Kupffer cells and pulmonary alveolar macrophages together constitute a macrophage-axis involved in the regulation of regional and systemic inflammatory responses. Systemic inflammatory response syndrome induced by overproduced pro-inflammatory mediators is the major cause of adult respiratory distress syndrome. In the present study, we examined the anti-inflammatory role of nitric oxide (NO) in a rat model of acute lung injury induced by hepatic ischemia-reperfusion (HI/R). The left and median lobes of the liver were subjected to 30 min of ischemia by clamping the relevant branches of hepatic artery and portal vein, followed by a 4-h reperfusion achieved by removal of the vascular clamp. Four groups of animals were studied: sham control + saline; sham control + N(omega)-nitro-L-arginine methyl ester (L-NAME, 10 mg/kg, i.v., 10 min before reperfusion); HI/R + saline; HI/R + L-NAME. Results show that (1) administration of L-NAME to rats subjected to HI/R decreased plasma NO levels; however, the attenuation of NO increased plasma alanine aminotransferase (ALT) activity and superoxide generation in the ischemic lobes of liver, compared to HI/R alone. (2) Inhibition of NO synthesis with L-NAME in rats subjected to HI/R also enhanced systemic inflammatory response as assessed by the increase in the number of circulating leukocytes and levels of plasma tumor necrosis factor-alpha (TNFalpha) and interleukin 1-beta (IL-1beta). (3) The overwhelming systemic inflammatory response induced by administration of L-NAME in rats subjected to HI/R also augmented pulmonary vascular permeability and superoxide generation in the lung tissue. (4) Pulmonary alveolar macrophages isolated from rats subjected to HI/R + L-NAME produced higher levels of TNFalpha and IL-1beta in the supernatant of culture medium than that of rats subjected to HI/R alone. (5) There were no differences between the groups of sham + saline and sham + L-NAME in terms of plasma NO levels and ALT activity, circulating leukocytes, superoxide generation in the liver and lung, lavage protein levels, and TNFalpha and IL-1beta levels in plasma and bronchoalveolar lavage fluid. Our results suggest that inhibition of NO synthesis by L-NAME in rats subjected to HI/R not only augments ischemic liver injury, but also enhances the systemic inflammatory response and exacerbates remote lung injury. The increase in TNFalpha and IL-1beta production by alveolar macrophages may, in part, account for L-NAME-induced enhancement of acute lung injury.     

Exhaled nitric oxide and acute lung injury in a rat model of extracorporeal circulation

Exhaled nitric oxide (NO) concentration, a marker of pulmonary inflammation, has been shown to be elevated in various models of acute lung injury (ALI). This study was undertaken to evaluate the pulmonary NO production in a rat model of postextracorporeal circulation (ECC) ALI. Wistar rats underwent either a partial femorofemoral ECC in normothermia for 3 h (n = 10) or a sham procedure (n = 10). The extracorporeal circuit consisted of a roller pump and a membrane oxygenator. Exhaled NO concentration was monitored with a chemiluminescence analyzer. After sacrifice, lungs were harvested for microscopic studies and to analyze the inducible nitric oxide synthase (iNOS) activity and expression (Western blot). ECC was responsible for an ALI characterized by a decreased arterial blood oxygen saturation (88.9% [51.7-94.2] vs. 93.7% [91.4-98.6] P = 0.005) and pulmonary histological changes (marked alveolar neutrophil infiltration; interstitial edema; intraalveolar hemorrhage). The lung injury score was significantly higher in the ECC group (n = 5; 3.0 [2-4]) in comparison to the sham group (n = 5; 1.0 [0-2]). Exhaled NO concentration remained stable throughout the experiment in all sham rats whereas it significantly increased in the ECC group from baseline (2 ppb [1-5]) until the end of experiment (33.5 ppb [1-47]). Lung iNOS activity and expression were also significantly increased in the ECC group. An increase in exhaled NO, however, did not correlate with the decrease in arterial oxygen pressure. ECC was responsible for an ALI in rats and for an elevated pulmonary NO production. Determination of the relationship between exhaled NO and the severity of the inflammatory process in ALI will require further studies.     

Effects of chronic hypoxia and altered hemodynamics on endothelial nitric oxide synthase expression in the adult rat lung.

Mechanisms that regulate endothelial nitric oxide synthase (eNOS) expression in normal and hypoxic pulmonary circulation are poorly understood. Lung eNOS expression is increased after chronic hypoxic pulmonary hypertension in rats, but whether this increase is due to altered hemodynamics or to hypoxia is unknown. Therefore, to determine the effect of blood flow changes on eNOS expression in the normal pulmonary circulation, and to determine whether the increase in eNOS expression after chronic hypoxia is caused by hemodynamic changes or low oxygen tension, we compared eNOS expression in the left and right lungs of normoxic and chronically hypoxic rats with surgical stenosis of the left pulmonary artery (LPA). LPA stenosis in normoxic rats reduced blood flow to the left lung from 9.8+/-0.9 to 0.8+/-0.4 ml/100 mg/min (sham surgery controls vs. LPA stenosis, P < 0.05), but there was not a significant increase in right lung blood flow. When compared with the right lung, eNOS protein and mRNA content in the left lung was decreased by 32+/-7 and 54+/-13%, respectively (P < 0.05), and right lung eNOS protein content was unchanged. After 3 wk of hypoxia, LPA stenosis reduced blood flow to the left lung from 5.8+/-0.6 to 1.5+/-0.4 ml/100 mg/min, and increased blood flow to the right lung from 5.8+/-0.5 to 10.0+/-1.4 ml/ 100 mg/min (sham surgery controls vs. LPA stenosis, P < 0.05). Despite reduced flow and pressure to the left lung and increased flow and pressure to the right lung, left and right lung eNOS protein and mRNA contents were not different. There were also no differences in lung eNOS protein levels when compared with chronically hypoxic sham surgery controls (P > 0.05). We conclude that reduction of pulmonary blood flow decreases eNOS mRNA and protein expression in normoxic adult rat lungs, and that hypoxia increases eNOS expression independently of changes in hemodynamics. These findings demonstrate that hemodynamic forces maintain eNOS content in the normoxic pulmonary circulation of the adult rat, and suggest that chronic hypoxia increases eNOS expression independently of changes in hemodynamics.     

还原型谷胱甘肽对大鼠脓毒症肺损伤外周血淋巴细胞凋亡率及TNF-α、IL-6水平的影响

目的观察还原型谷胱甘肽对大鼠脓毒症肺损伤外周血淋巴细胞凋亡率及血浆细胞因子TNF-α、IL-6水平的影响，探讨还原型谷胱甘肽对大鼠脓毒症肺损伤的保护作用及其机制。方法应用盲肠结扎穿孔（CLP）法复制大鼠脓毒症肺损伤模型。将清洁级雄性SD大鼠112只，随机分成假手术组（Sham）、脓毒症肺损伤组（ALI）、还原型谷胱甘肽治疗组（GSH）、左旋氧氟沙星治疗组（LEV），每组再分为3、6、12、24h等4个亚组，每个亚组n=7。观察大鼠脓毒症肺损伤肺组织的病理形态学改变，并检测外周血淋巴细胞凋亡率及血浆TNF-α、IL-6水平的变化。结果在脓毒症肺损伤组及左旋氧氟沙星治疗组淋巴细胞凋亡率较假手术组及GSH治疗组明显升高（P〈0．05）；在脓毒症肺损伤组血浆TNF-α水平在CLP术后6h出现升高，较GSH治疗组升高明显（P〈0．01）。脓毒症肺损伤组大鼠血浆IL-6水平于CLP术后3h升高，GSH治疗组CLP术后3h血浆IL-6水平较脓毒症肺损伤组低（P〈0．05）。脓毒症肺损伤组大鼠病理显示明显肺损伤，GSH治疗组大鼠肺损伤程度明显减轻。结论还原型谷胱甘肽能显著抑制外周血淋巴细胞凋亡及血浆TNF-α和IL-6表达水平，对大鼠脓毒症急性肺损伤具有明显的保护作用。     

肠系膜淋巴管结扎对失血性休克大鼠肺组织一氧化氮及其表达的影响

目的 观察结扎肠系膜淋巴管对不同时期重症失血性休克大鼠肺组织一氧化氮（NO）及其表达的影响，探讨肠淋巴途径在休克大鼠急性肺损伤（ALI）中的作用。方法 雄性Wistar大鼠78只，按随机数字表法分为假手术组（n=6）、休克组（n=42）和结扎组（n=30）。休克组与结扎组复制重症失血性休克模型，结扎组于休克复苏后行肠系膜淋巴管结扎术；休克组于休克后90min、输液复苏后0h，休克组及结扎组于输液复苏后1、3、6、12和24h各时间点处死大鼠，制备肺组织匀浆，检测NO及其合酶的变化；用逆转录-聚合酶链反应（RT—PCR）测定各组大鼠肺组织诱生型一氧化氮合酶（iNOS）．mRNA表达。结果 休克组大鼠复苏后3h肺组织NO含量、NOS活性及iNOSmRNA表达开始升高，复苏后6～12h持续在较高水平，均显著高于假手术组、休克后90min及复苏后0h（P〈0．05或P〈0．01）；结扎组仅于3h和6h增高，且结扎组复苏后6、12和24h肺组织NO含量、NOS活性以及iNOSmRNA表达均显著低于休克组相同时间点（P〈0．05或P〈0．01）。结论 肠系膜淋巴管结扎可降低重症失血性休克大鼠肺组织NO生成及iNOSmRNA表达，从而减轻肺损伤。     

Modulation of hypoxic pulmonary vasoconstriction is time and nitric oxide dependent in a peritonitis model of sepsis

Objective This study assessed modulation of hypoxic pulmonary vasoconstriction (HPV) in isolated perfused rat lungs during sepsis induced by cecal ligation and perforation (CLP) at different times and its relationship to nitric oxide synthases (NOS).Design and setting Prospective controlled trial in a university research laboratory.Subjects 102 male Sprague-Dawley rats.Interventions Groups 1–3 received sham laparotomy 6 h before lung isolation: group 1, only laparotomy; group 2, concurrently l-N ⁶-(1-iminoethyl)-lysine (L-NIL, 3 mg/kg); group 3, concurrently N -nitro-l-arginine methylester (L-NAME, 5 mg/kg). Groups 4–6 received CLP 6 h before lung isolation: group 4, only CLP; group 5, concurrently L-NIL; group 6, concurrently L-NAME. The same experiments were carried out with sham and CLP treatment for 24 h (groups 7–12). Exhaled NO from rats lungs was measured after anesthesia and tracheostomy. After the pulmonary circuit was isolated and perfused, angiotensin II (0.1 µg) was injected into the inflow tract. The lungs were ventilated with the hypoxic mixture (HPV, 3% O₂) for 10 min and then again with the normoxic mixture (21% O₂) for an equal period. Changes in perfusion pressure were measured. Endothelial (eNOS) and inducible NOS (iNOS) expression of the lungs was determined.Measurements and results Treatment with L-NAME but not L-NIL increased HPV in sham lungs. HPV was unaltered after CLP 6 h and decreased after CLP 24 h compared to sham. In CLP animals eNOS protein expression was reduced whereas iNOS expression was increased compared to sham animals. Exhaled NO, reflecting NOS activity was twice as high in the CLP 24 h group than in the CLP 6 h group.Conclusions In the CLP sepsis model modulation of HPV was time-dependent. In addition, vasoconstriction to hypoxic stimuli was dependent on NOS activity.L.G. F. is supported by Innovative Medizinische Forschung Münster, Germany (Fi-1-2000-4)     

Involvement of endogenous opioid peptides and nitric oxide in the blunted chronotropic and inotropic responses to beta-adrenergic stimulation in cirrhotic rats

It is well known that chronotropic and inotropic responses to beta-adrenergic stimulation are impaired in cirrhosis, but the exact reason is not clear. Considering the inhibitory effect of endogenous opioid peptides and nitric oxide (NO) on beta-adrenergic pathway, we examined their roles in hyporesponsiveness of isolated atria and papillary muscles to isoproterenol stimulation in cirrhotic rats. Cirrhosis was induced by chronic bile duct ligation. Four weeks after ligation or sham operation, the responses of the isolated atria and papillary muscles to isoproterenol stimulation were evaluated in the absence and presence of naltrexone HCl (10(-6) m), N(omega)-nitro-L-arginine methyl ester (L-NAME, 10(-4) m), and naltrexone plus L-NAME in the organ bath. Considering the role of inducible NOS (iNOS) in hemodynamic abnormalities of cirrhotic rats, the chronotropic and inotropic responses of cirrhotic rats to isoproterenol stimulation were also assessed in the presence of aminoguanidine (a selective inhibitor of iNOS, 3 x 10(-4) m). Sham operation had no significant effect on basal atrial beating rate, contractile force, and maximal time derivatives for the development and the dissipation of papillary muscle tension. The basal atrial beating rate of cirrhotic rats did not show any significant difference compared with the sham-operated ones; however, the basal contractile parameters were significantly decreased in cirrhosis. Although the maximum effects of isoproterenol on chronotropic and inotropic responses were significantly reduced in cirrhotic rats, there was no difference in half-maximal effective concentrations of isoproterenol in these concentration-response curves. The basal abnormalities and the attenuated chronotropic and inotropic responses to isoproterenol were completely corrected by the administration of naltrexone, L-NAME and aminoguanidine. Concurrent administration of naltrexone and L-NAME also restored to normal the basal abnormalities and the blunted responses to isoproterenol in cirrhotic rats, and did not show any antagonistic effect. Based on these findings, both the endogenous opioid peptides and NO may be involved in the attenuated chronotropic and inotropic responses to beta-adrenergic stimulation in cirrhosis. It seems that the iNOS activity results in NO-induced hyporesponsiveness to beta-adrenergic stimulation in cirrhosis.     

Alteration of the extracellular matrix and alpha‐gal antigens in the rat lung scaffold reseeded using human vascular and adipogenic stromal cells

Regenerated organs are expected to solve the problem of donor organ shortage in transplantation medicine. One approach to lung regeneration is to decellularize the organ and reseed it with selected cells. An advantage of the procedure is reduced immunogenicity, because all cells can be theoretically replaced by autologous cells. However, little is known regarding the extracellular matrix (ECM) damage during decellularization and ECM reconstruction process in the organ regeneration. We aimed to evaluate ECM damage and reconstruction of the decellularized–recellularized rat lung, including the removal of alpha‐gal xenoantigens. Rat lungs were perfused with sodium dodecyl sulfate and Triton X‐100 via the pulmonary artery, after which the decellularized scaffold was reseeded with rat or human endothelial cells and adipose‐derived stem cell (ASCs). The ECM and alpha‐gal antigen were evaluated using immunohistochemistry, western blotting, and a glycosaminoglycan assay. Alcian blue staining revealed increased production of proteoglycan following the addition of ASCs to the rat lung recellularized with rat lung microvascular endothelial cells. Glycosaminoglycan levels decreased in the decellularized lung and increased in the recellularized lung, especially in the ASC‐treated group. Immunohistochemical expression of the alpha‐gal protein was decreased to an undetectable level in the decellularized lung tissue and disappeared after recellularization with human cells. In western blot analysis, the bands of alpha‐gal protein almost disappeared after recellularization with human cells. In conclusion, characteristics of the regenerated ECM might depend on the species and type of cells used for recellularization. Therefore, alpha‐gal antigen might be eliminated after a prolonged culture, when using human cells.     

Acute intravenous injection and short‐term oral administration of NG‐nitro‐l‐arginine methyl ester to the rat provoke increased pressor responses to agonists and hypertension,but not inhibition of acetylcholine‐induced hypotensive responses

In experiments in vivo, we studied whether the endothelial dysfunction induced by nitric oxide (NO) synthesis inhibition is simultaneously or sequentially manifested as a reduced level of endothelium‐dependent agonist‐induced vasodilatation, an increased responsiveness to vasoconstrictors, and hypertension. Vascular responses to acetylcholine, phenylephrine, and angiotensin II were measured in pithed rats after acute intravenous injection (100 mg/kg) and short‐term oral administration of N^G‐nitro‐l ‐arginine methyl ester (l ‐NAME; 60 mg/kg per day) for 1 and 3 days (l ‐NAME_1d and l ‐NAME_3d, respectively). Pithed rats were chosen because drug‐induced cardiovascular responses reflect only peripheral effects. Parallel experiments examined mean arterial pressure (MAP) values in anesthetized rats. After short‐term l ‐NAME_1d and l ‐NAME_3d treatments, the MAP was significantly elevated in anesthetized but not pithed rats. Acute intravenous administration of l ‐NAME elevated MAP in pithed rats. Intravenous infusion of phenylephrine was used to compensate for the pressor response induced by l ‐NAME in pithed animals. The maximum decrease and duration of the hypotensive responses to acetylcholine were unaltered by the acute and both short‐term l ‐NAME treatments in pithed rats. These treatments, on the other hand, increased phenylephrine‐ and angiotensin II‐induced pressor responses in pithed animals. In isolated aortic rings prepared from pithed rats treated acutely and short‐term with l ‐NAME, acetylcholine‐induced relaxations were inhibited. Thus, the inhibition of NO‐dependent vasodilator tone after acute intravenous injection and short‐term oral l ‐NAME administration may be associated with vascular smooth muscle hyper‐responsiveness to pressor agonists and hypertension, whereas the hypotensive responses to acetylcholine could not be associated with the l ‐NAME‐induced endothelial dysfunction in pithed rats.     

Role of neutrophil elastase in development of pulmonary vascular injury and septic shock in rats

Prostacyclin prevents pulmonary vascular injury and shock by inhibiting increases in lung tissue levels of TNF in rats administered endotoxin. We previously reported that NO derived from eNOS increases endothelial production of prostacyclin. Because neutrophil elastase has been shown to decrease endothelial production of prostacyclin by inhibiting NOS activity, we examined whether neutrophil elastase inhibitors reduce pulmonary vascular injury and hypotension by inhibiting the decrease in pulmonary endothelial production of prostacyclin in rats administered endotoxin. Animals were pretreated with sivelestat or L-658,758, neutrophil elastase inhibitors, before endotoxin administration. Lung tissue levels of 6-keto-prostaglandin F1alpha were markedly increased after endotoxin administration, followed by a rapid decrease to baseline levels. Sivelestat and L-658,758 inhibited these decreases as well as inhibiting increases in lung tissue levels of TNF and lung wet-to-dry weight ratios in animals administered endotoxin. These inhibitors also reduced hypotension and inhibited increases in lung tissue levels of mRNA of the inducible form of NOS in animals administered endotoxin. The effects of neutrophil elastase inhibitors were completely reversed by pretreatment with nitro-L-arginine methyl ester, an inhibitor of NOS, or indomethacin, a nonspecific cyclooxygenase inhibitor. These observations suggested that neutrophil elastase might decrease the pulmonary endothelial production of prostacyclin by inhibiting endothelial NO production, thereby contributing to the development of pulmonary vascular injury and shock through increases in lung tissue levels of TNF in rats administered endotoxin.     

Involvement of CaM kinase II in the impairment of endothelial function and eNOS activity in aortas of Type 2 diabetic rats

In the present sutdy, we have examined the relationship between the CaMKII (Ca(2+)/calmodulin-dependent protein kinase II) pathway and endothelial dysfunction in aortas from GK (Goto-Kakizaki) Type 2 diabetic rats. The ACh (acetylcholine)-induced relaxation and NO production were each attenuated in diabetic aortas (compared with those from age-matched control rats). ACh-stimulated Ser(1177)-eNOS (endothelial NO synthase) phosphorylation was significantly decreased in diabetic aortas (compared with their controls). ACh markedly increased the CaMKII phosphorylation level within endothelial cells only in control aortas (as assessed by immunohistochemistry and Western blotting). ACh-stimulated Thr(286)-CaMKII phosphorylation within endothelial cells was significantly decreased in diabetic aortas (compared with their controls). The ACh-induced relaxations, NO production, eNOS phosphorylation, and CaMKII phosphorylation were inhibited by KN93 and/or by lavendustin C (inhibitors of CaMKII) in control aortas, but not in diabetic ones. Pre-incubation of aortic strips with a PP (protein phosphatase)-1 inhibitor, PPI2 (protein phosphatase inhibitor 2), or with a PP2A inhibitor, CA (cantharidic acid), corrected the above abnormalities in diabetic aortas. The expression of PP2A type A subunit was increased in diabetic aortas. The ACh-stimulated Thr(320)-phosphorylation level of PP1α was lower in diabetic aortas than in their controls, but the total PP1α protein level was not different. These results suggest that the aortic relaxation responses, NO production, and eNOS activity mediated by CaMKII phosphorylation are decreased in this Type 2 diabetic model, and that these impairments of CaMKII signalling may be, at least in part, due to enhancements of PP1α activity and PP2A expression.     

Nitric oxide and renal and cardiac dysfunction in cirrhosis

Nitric oxide (NO) has diverse physiological and pathophysiological effects. The roles of NO in the renal and cardiac dysfunction found in cirrhosis are reviewed. In the kidneys of experimental animals with cirrhosis, several lines of evidence speak in favour of an enhanced production of NO, through the activation of both endothelial constitutive and inducible isoforms of NO synthase. In contrast with the situation in normal animals, inhibition of NO synthesis in rats with cirrhosis improves sodium and water excretion via blood pressure-dependent and -independent mechanisms, which indicates that the renal sodium and water retention of cirrhosis is related to an excess of NO production. The deleterious effect of excessive NO on the kidney may be mediated by peroxynitrite, a potent oxidant that is readily formed whenever superoxide anions and the *NO radical are produced together. The peroxidation of arachidonic acid by peroxynitrite leads to the formation of F(2a)-isoprostanes, which are powerful renal vasoconstrictors. F(2a)-isoprostane levels are correlated with the severity of liver injury during cirrhosis. However, whether peroxynitrite or F(2a)-isoprostanes are the elusive mediator of the NO-induced renal alterations in cirrhosis remains to be firmly established. NO is also involved in cardiac contractility, probably in the normal heart as well as in disease conditions such as non-cirrhotic and cirrhotic cardiomyopathy. In the latter state, evidence suggests that inducible NO synthase attenuates ventricular contractility, mediated by cGMP. Another gas that transduces its signal through cGMP, carbon monoxide, is also likely to play a role in cirrhotic cardiomyopathy, but the nature of the interaction between NO and carbon monoxide in this syndrome remains unclear.     

Role of interferon-gamma in lung inflammation following cecal ligation and puncture in rats.

Interferon-gamma (IFN-gamma) has been implicated in the mortality of animal models of endotoxemia. On the other hand, the specific role of IFN-gamma in the development of organ inflammation in a model of polymicrobial sepsis has not been elucidated. In this study, we hypothesized that IFN-gamma plays an important role in lung inflammation after cecal ligation and puncture (CLP). To verify this hypothesis, lung tissue was removed 5 h after CLP or from sham controls. The mRNA expression (by RT-PCR) of IFN-gamma was increased in lung homogenates of CLP rats compared to sham controls. Using immunohistochemistry, we show for the first time the increased presence of IFN-gamma staining cells in the lung following CLP. Only very small amounts of positive staining for IFN-gamma was observed in lungs of sham controls. The presence of IFN-gamma in the lung 5 h after CLP correlated with a twofold increases in lung superoxide generation and MPO activity (index of neutrophil sequestration). Plasma and lung nitrite levels (breakdown product of nitric oxide) were also significantly increased in CLP rats. IFN-gamma antibody (1.2 mg/kg, i.v.) administered immediately after CLP significantly decreased lung superoxide levels to levels similar to the sham controls without affecting MPO activity, or lung or plasma nitrite levels. These results provide evidence that IFN-gamma may contribute to lung inflammation 5 h following CLP via increased production of superoxide.     

MODSE各脏器纤维连接蛋白免疫组织化学表达的研究

目的 通过观察老年多器官功能障碍综合征(MODSE)的纤维连接蛋白(FN)在各重要器官组织(心、脑、肺、肾和肝)的分布特点，探讨MODSE的内皮损伤特点及凝血功能失调机制。方法建立盲肠结扎穿孔术(CLP)的MODSE模型，设立青年多器官功能障碍综合征(MODS)组及两组相应的假手术对照组，分别于术后6、12、24、48和72h采用链霉素一卵白素一生物素的免疫组织化学技术(LSAB)对各重要器官进行研究。结果MODSE和青年MODS组FN表达强度主要为阴性和弱阳性，MODSE组比青年MODS组FN降低得快且早，而老年假手术组(SOGE组)也比青年假手术组(SOG)的FN表达强度要弱一些，各组织一般在0．5～48．0h降低得比较显著。结论 MODSE、MODS和SOGE均存在不同程度的内皮细胞损伤和凝血功能障碍，其中以MODSE最为严重。     

去铁胺对大鼠肺组织低氧诱导因子-1表达及对模拟高原低氧大鼠肺组织结构的影响

目的:观察去铁胺对大鼠肺组织低氧诱导因子-1(HIF-1α)表达及对模拟高原低氧环境下肺结构的影响。方法:实验分成两部分,(1)25只Wistar大鼠随机分成5组,腹腔注射去铁胺(DFX)200mg/kg后,分别用RT-PCR和免疫组化方法在各个时相点(0、2、4、8、24h)检测肺组织HIF-1α mRNA和蛋白质的表达。(2)40只Wistar大鼠随机分成5组,每组8只。常氧对照组(N),急性低氧对照组(H0),急性低氧组(H1),DFX处理组(DFX0),DFX处理+急性低氧组(DFX1)。各组动物经相应处理后,测定N、H0、DFX0组肺组织HIF-1α mRNA,观察N、H1、DFX1组肺显微及超微结构变化并检测肺组织一氧化氮浓度及Na+-K+-ATP酶活性。结果:(1)大鼠腹腔注射DFX后肺组织未表达HIF-1α蛋白质,对照组(0h)大鼠肺组织少量表达HIF-1α mRNA,2h后开始升高,4h达峰值(P<0.01),以后逐渐下降,24h后基本恢复到正常对照组水平。(2)大鼠腹腔注射DFX200mg/kg,1次/d,5d后,DFX0组HIF-1α mRNA表达水平显著高于H0和N组(P<0.01)。(3)经模拟海拔6000m急性低氧24h后,H1组肺组织NO浓度和Na+-K+-ATP酶活性低于N组(P<0.01),而DFX1较H1组明显升高(P<0.01)。(4)经模拟海拔6000m急性低氧24h后,H1组肺出现明显的间质性水肿,而DFX1组则水肿明显减轻。结论:DFX可以促进大鼠肺组织表达HIF-1α mRNA;间断腹腔注射DFX可以减轻大鼠低氧性肺间质水肿并提升肺组织NO浓度和Na+-K+-ATP酶活性。     

L-NAME enhances microcirculatory congestion and cardiomyocyte apoptosis during myocardial ischemia-reperfusion in rats

Besides necrosis, apoptosis is the other major mode of cardiomyocyte loss in ischemic cardiovascular disease. In the present study, we examined the hypothesis that nitric oxide (NO) protects myocardial function by improving myocardial microcirculation and attenuating cardiomyocyte apoptosis in a rat model of myocardial ischemia/reperfusion (MI/R). The left main coronary artery of anesthetized male rats was ligated for 40 min, followed by 4 h reperfusion. Four groups of animals were studied: sham operated control + saline; sham operated control + N(W)-nitro-L-arginine methyl ester (L-NAME); MI/R + saline; MI/R + L-NAME (10 mg/kg, iv, 10 min prior to reperfusion). Results show that MI/R caused a decrease in mean arterial blood pressure (MABP), cardiac index (CI), and stroke volume index (SVI). Inhibition of NO synthesis by L-NAME attenuated plasma NO levels, but increased MABP and SVR in sham control rats and rats subjected to MI/R, and further depressed left ventricular function in rats subjected to MI/R as indicated by decreased CI and SVI. Furthermore, administration of L-NAME to rats subjected to MI/R enhanced cardiomyocyte apoptosis as indicated by a significant increase in DNA fragmentation compared to rats with MI/R alone. Histological study revealed that L-NAME caused arterial constriction and congestion of red blood cells in arteries and capillaries in the peri-ischemic areas of the hearts in rats subjected to MI/R and, interestingly, also in the sham control rats. Data suggest that the mechanism of increased reperfusion injury may be attributable to a "no-reflow" phenomenon induced by L-NAME, resulting in increased cardiomyocyte apoptosis secondary to ischemia and enhanced cytochrome-c release from mitochondria. In addition, cardiac injury may be increased due to the augmented oxygen consumption of cardiomyocytes caused by the increased SVR and afterload. These results suggest that endogenous NO may act to improve myocardial microvascular perfusion, reduce SVR, and limit cardiomyocyte apoptosis, thereby, attenuating myocardial dysfunction induced by MI/R.