Hypoxia inducible factor-1αaccumulation in steatotic liver preservation:Role of nitric oxide

AIM:To examine the relevance of hypoxia inducible factor(HIF-1)and nitric oxide(NO)on the preservation of fatty liver against cold ischemia-reperfusion injury(IRI). METHODS:We used an isolated perfused rat liver model and we evaluated HIF-1αin steatotic and non-steatotic livers preserved for 24 h at 4℃in University of Wisconsin and IGL-1 solutions,and then subjected to 2 h of normothermic reperfusion.After normoxic reperfusion,liver enzymes,bile production,bromosulfophthalein clearance,as well as HIF-1αand NO[endothelial NO synthase(eNOS)activity and nitrites/nitrates]were also measured.Other factors associated with the higher susceptibility of steatotic livers to IRI,such as mitochondrial damage and vascular resistance were evaluated. RESULTS:A significant increase in HIF-1αwas found in steatotic and non-steatotic livers preserved in IGL-1 after cold storage.Livers preserved in IGL-1 showed a significant attenuation of liver injury and improvement in liver function parameters.These benefits were enhanced by the addition of trimetazidine(an antiischemic drug),which induces NO and eNOS activation, to IGL-1 solution.In normoxic reperfusion,the presence of NO favors HIF-1αaccumulation,promoting also the activation of other cytoprotective genes,such as hemeoxygenase-1. CONCLUSION:We found evidence for the role of the HIF-1α/NO system in fatty liver preservation,especially when IGL-1 solution is used.

Nitric oxide: orchestrating hypoxia regulation through mitochondrial respiration and the endoplasmic reticulum stress response

Mitochondria have long been considered to be the powerhouse of the living cell, generating energy in the form of the molecule ATP via the process of oxidative phosphorylation. In the past 20 years, it has been recognised that they also play an important role in the implementation of apoptosis, or programmed cell death. More recently it has become evident that mitochondria also participate in the orchestration of cellular defence responses.At physiological concentrations, the gaseous molecule nitric oxide (NO) inhibits the mitochondrial enzyme cytochrome c oxidase (complex IV) in competition with oxygen. This interaction underlies the mitochondrial actions of NO, which range from the physiologi- cal regulation of cell respiration, through mitochondrial signalling, to the development of “metabolic hypoxia” – a situation in which, although oxygen is available, the cell is unable to utilise it.

Inhibition of Expression of Hypoxia-inducible Factor-1α mRNA by Nitric Oxide in Hypoxic Pulmonary Hypertension Rats

In order to study the effect of nitric oxide (NO) on the expression of hypoxia inducible factor 1 alpha (HIF 1α) mRNA in hypoxic pulmonary hypertension (HPH) rats, 30 healthy male Wistar rats were randomly divided into normoxic control group, chronic hypoxic group and hypoxia plus L argine (L Arg) group. The animal model of HPH was developed. The mean pulmonary arterial pressure (mPAP) was measured by inserting a microcatheter into the pulmonary artery. The HIF 1α mRNA expression levels were detected by in situ hybridization (ISH) and semiquantitative RT PCR. It was found that after 14 days hypoxia, the mPAP in normoxic control group (17.6±2 7 mmHg,1 mmHg=0 133 kPa) was significantly lower than that in chronic hypoxic group(35.8±6.1 mmHg, t =0.2918, P <0.05) and mPAP in chronic hypoxic group was higher than that in hypoxia plus L argine group(24.4±3.8 mmHg, t =0.2563, P <0.05). ISH showed that the expression of HIF 1α mRNA in the intraacinar pulmonary arteriolae (IAPA) in normoxic control group (0.1076±0.0205) was markedly weaker than that in chronic hypoxic group (0.3317±0.0683, t =3.125, P <0.05) and that in chronic hypoxic group was stronger than that in hypoxia plus L argine group (0.1928±0.0381, t =2.844, P <0.05). RT PCR showed that the content of HIF 1α mRNA in chronic hypoxic group (2.5395±0.6449) was 2.16 times and 1.75 times higher than that in normoxic control group (1.1781±0.3628) and hypoxia plus L argine group (1.4511±0.3981), respectively. It is concluded that NO can reduce the mPAP by the inhibition of the expression of HIF 1α mRNA, which may be one of the mechanisms through which NO affects the pathogenesis of HPH.

EFFECTS OF HEMOGLOBIN ON SERUM NITRIC OXIDECONCENTRATION AND HEMODYNAMICS PATTERN CHANGES IN CIRRHOTIC RATS

Objective To investigate the effects of hemoglobin (Hb) on serum nitric oxide (ON) concentrationand hemodynamics pattern changes in rats with cirrhosis. Methods Cirrhosis model was induced in male SDrats by injection of 60% CCl4 oily solution subcutaneously. Cirrhotic rats were treated with erythropoietin(100U/kg) injected subcutaneously for 2 weeks. Mean arterial pressure (MAP), cardiac output (CO), cardiac index(CI), splanchnic vascular resistance (SVR), splanchnic blood flow (SBF) and serum NO concentration weredetermined in erythropoietin - treated, erythropoietin - untreated cirrhotic rats and controls by using 57Co - labelledmicrosphere technique and a fluorometric assay, respectively. In addition, blood Hb levels were also measured inthe 3 groups. Results Untreated cirrhotic rats had significantly lower MAP, SVR, Hb and higher Co, CI, SBFand NO concentration than those of the controls (P<0.01). In treated cirrhotic rats, erythropoietin significantlyattenuated the increase of CO, CI, SBF, NO concentration and the decrease of MAP and SVR. In cirrhotic rats,opoetin beta in subcutaneous dose of 100U·kg-1·d-1 induced a markedly increment of blood Hb levels anddecrement of NO concentration in comparison with untreated cirrhotic rats (181±11g/L vs 120±15g/L,1.14±0.62μmol/L vs 4.20±1.25μmol/L). Conclusion The endogenous NO may play an important role in thechanges of hemodynamics pattern in cirrhosis, and hyperdynamic circulatory status in rats with cirrhosis might beameliorated by inactivation of overproduced NO by increasing hemoglobin with erythropoietin.

Role of nitric oxide in the maintenance of pluripotency and regulation of the hypoxia response in stem cells

Stem cell pluripotency and differentiation are global processes regulated by several pathways that have been studied intensively over recent years. Nitric oxide(NO) is an important molecule that affects gene expression at the level of transcription and translation and regulates cell survival and proliferation in diverse cell types. In embryonic stem cells NO has a dual role, controlling differentiation and survival, but the molecular mechanisms by which it modulates these functions are not completely defined. NO is a physiological regulator of cell respiration through the inhibition of cytochrome c oxidase. Many researchers have been examining the role that NO plays in other aspects of metabolism such as the cellular bioenergetics state, the hypoxia response and the relationship of these areas to stem cell stemness.

Differential <i>β</i>₁Cardiac Adrenoceptor Modulation of Nitric Oxide Isoforms by <i>β</i>₁IgG from Patients with Periodontitis during Short-Term Hypoxia

Background: We demonstrated previously that serum IgG from periodontitis patients interacting with the second extracellular loop of the human cardiac β1 adrenoreceptors triggers the production of second messengers. In this paper we quantified the production of nitrates/nitrites and nitric oxide (NO), which in turn induces nitric oxide synthase (NOS) mRNA expression. Methods: We determined using β1 IgG, NOS activity isoforms, NOS expression, nitrate/nitrite assay, cGMP accumulation and PKC activity. Results: We established that serum β1 IgG autoantibodies and NO might be considered as early markers in normoxia/hypoxia system in rat isolated atria. The β1 IgG autoantibodies from periodontitis patients, while stimulating myocardial atria β1 adrenoreceptors, exert an increase on NO levels indirectly quantified as nitrite/nitrate, which acts as NO-storage molecules with significant increase in neuronal NOS (nNOS) and inducible NOS (iNOS) mRNA levels in hypoxia conditions. The significant increase in nNOS/iNOS mRNA and NOS activity as well as in NO levels after short-time hypoxia in rat isolated atria was detected. The expression of these genes are related with the increase in atria dF/dt, cyclic GMP (cGMP) and protein kinase C (PKC) activity and resemble the results obtained by Isoproterenol, an β1 adrenoreceptor agonist. Conclusion: These findings indicate that short-term hypoxia up-regulated rat atria NO/NOS system in the presence of β1 IgG autoantibodies shows that an antibody interacting with rat atria β1 adrenoreceptor can act as expression inducer of proinflammatory NO and its metabolites and that it might be useful and helps to maintain heart function and to prevent necrosis and subsequent loss of heart function during hypoxia.

Changes of Gastric Nitric Oxide in Neonatal Rats with Hypoxic-Ischemic Encephalopathy

In order to study the changes of nitric oxide (NO) in gastric wall in hy-poxic neonatal rats, the activity of nitric oxide synthase (NOS) of gastric wall was measured and the NADPH-diaphorase biochemistry test was taken to show the distribution of NOS in the gastric wall of neonatal rats. The results showed that compared with normal rats, NOS had no significant changes in the acute hy-poxic rats (P>0. 05). However, in hypoxic-ischemic encephalopathy (HIE) neonatal rats, the activity of NOS was markedly increased (P<0. 01), and the NOS positive reactive products were markedly increased in the gastric muscle, but no changes in the mucosal and submucosal layers were observed. The results suggest that the decreased gastric motivation and the gastric mucosal lesions caused by asphyxia are associated with the changes of NO in gastric wall.

Tongxinluo Inhibits Cyclooxygenase-2, Inducible Nitric Oxide Synthase, Hypoxia-inducible Factor-2α/Vascular Endothelial Growth Factor to Antagonize Injury in Hypoxia-stimulated Cardiac Microvascular Endothelial Cells

Background： Endothelial dysflinction is considered as the initiating process and pathological basis of cardiovascnlar disease. Cyclooxygenase-2 （COX-2） and prostacyclin synthase （PGIS）, inducible nitric oxide synthase （iNOS） and endothelial NOS （eNOS） are key enzymes with opposing actions in inflammation and oxidative stress, which are believed to be the major driver of endothelial dysfunction. And in hypoxia （Hx）, Hx-inducible factor （HIF）-1α and HIF-2α are predominantly induced to activate vascular endothelial growth factor （VEGF）, restllting in abnormal proliferation. Whether and how Tongxinluo （TXL） modulates COX-2, PGIS, iNOS, eNOS, HIF-1α, HIF-2α, and VEGF in Hx-stimulated human cardiac microvascular endothelial cells （HCM ECs） have not been clarified. Methods： HCMEC were treated with CoCl2 to mimic Hx and the mRNA expressions of COX-2, PGIS, iNOS, eNOS, HIF-1α, HIF-2α. and VEGF were first confirmed, and then their mRNA expression and protein content as well as the cell pathological alterations were evaluated for TXL treatment with different concentrations, In addition, the effector molecular of inflammation prostaglandin E2 （PGE2） and the oxidative marker nitrotyrosine （NT） was adopted to reflect HCMEC in.jury. Results： Hx could induce time-dependent increase of COX-2, iNOS, HIF-2α, and VEGF in HCMEC. Based on the Hx-induced increase, TXL could mainly decrease COX-2, iNOS, HIF-2α, and VEGF in a concentration-dependent manner, with limited effect on the increase of PGIS and eNOS. Their protein contents verified the mRNA expression changes, which was consistent with the cell morphological alterations. Furthermore, high dose TXL could inhibit the Hx-induced increase of PG E, and NT contents, attenuating the inflammatory and oxidative injury. Conclusions： TXL could inhibit inflammation-related COX-2, oxidative stress-related iNOS, and H IF-2α/VEGF to antagonize Hx-induced HCMEC injury.

EP300 contributes to high-altitude adaptation in Tibetans by regulating nitric oxide production

The genetic adaptation of Tibetans to high altitude hypoxia likely involves a group of genes in the hypoxic pathway, as suggested by earlier studies. To test the adaptive role of the previously reported candidate gene EP300 （histone acetyltransferase p300）, we conducted resequencing of a 108.9 kb gene region of EP300 in 80 unrelated Tibetans. The allele-frequency and haplotype-based neutrality tests detected signals of positive Darwinian selection on EP300 in Tibetans, with a group of variants showing allelic divergence between Tibetans and lowland reference populations, including Han Chinese, Europeans, and Africans. Functional prediction suggested the involvement of multiple EP300 variants in gene expression regulation. More importantly, genetic association tests in 226 Tibetans indicated significant correlation of the adaptive EP300 variants with blood nitric oxide （NO） concentration. Collectively, we propose that EP300 harbors adaptive variants in Tibetans, which might contribute to high-altitude adaptation through regulating NO production.

Salviae miltiorrhizae ameliorates cirrhosis and portal hypertension by inhibiting nitric oxide in cirrhotic rats

OBJECTIVE: To determine the effect of Salviae miltiorrhizae on cirrhosis and portal hyperiension by inhibiting nitric oxide synthase type Ⅱ (NOSⅡ) in rats. METHODS: Real time RT-PCR was used to detect the expression of NOSII mRNA. The enzymatic activity of nitric oxide synthase and the circulating levels of nitric oxide (NO), systemic and portal hemodynamics, and quantification of cirrhosis were measured with highly sensitive methods. Traditional Chinese medicine was utilized to treat cirrhotic rats and the function of NO was evaluated. Double-blind method was applied in the experiment constantly. RESULTS: The concentration of NO increased markedly at all stages of cirrhosis, and so did the enzymatic activity of NOS, antl the iNOSmRNA expressed greatly. Meanwhile the portal-venous-pressure (PVP), portal-venous-now (PVF) increased significantly. NO, Nos and iNOSmHNA were positively correlated to the quanlity of hepatic fihrosis. Salviae Miltiorrhizae significantly inhibited NO production and inhibited the expression of iNOSmRNA. CONCLUSIONS: The increased hepatic expression of NoSIⅡ is one of the important factors causing cirrhosis and portal hypertension. Salviae Miltiorrhizae significantly ameliorates cirrhosis and portal hypertension.

Hypoxia-inducible factor 1 alpha upregulates the expression of inducible nitric oxide synthase gene in pulmonary arteries of hypoxic rat

Objective To investigate the expression of hypoxia inducible factor 1 alpha (HIF 1α) and inducible nitric oxide synthase (iNOS) genes in rats’ pulmonary arteries in different phases of hypoxia induced pulmonary hypertension development Methods Models of chronic hypoxic pulmonary hypertension rat were duplicated by intermittent hypoxia Mean pulmonary arterial pressure (mPAP) was measured by right heart catheterization HIF 1α and iNOS messenger ribonucleic acid (mRNA) were detected by in situ hybridization HIF 1α and iNOS protein were measured by immunohistochemical analysis Results Expression of HIF 1α protein was upregulated in pulmonary arterial tunica intimae of all hypoxic rats In pulmonary arterial tunica media, the level of HIF 1α protein was markedly upregulated at days 3 and 7 of hypoxia ( P 【0 01), then tended to restore at 14 days and 21 days HIF 1α mRNA levels in pulmonary arteries of rats began to increase significantly at day 14 of hypoxia ( P 【0 01) Expression of iNOS mRNA and protein in pulmonary arteries of rats were upregulated by hypoxia for 3 days ( P 【0 01), then reached its peak and maitained the same level while the extension of hypoxia Linear correlation analysis showed that iNOS protein was associated with both mean pulmonary arterial pressure ( r =0 74, P 【0 01) and hypoxic pulmonary vascular remodeling ( r =0 78, P 【0 01), whereas the inverse was associated with HIF 1α protein ( r =-0 52, P 【0 01) Conclusions HIF 1α and iNOS are both involved in the pathogenesis of hypoxia induced pulmonary hypertension in rat HIF 1α protein may upregulate the expression of iNOS gene by transcriptional activation; in addition, iNOS protein may inhibit the expression of HIF 1α protein

Tetrandrine Ameliorates Cirrhosis and Portal Hypertension by Inhibiting Nitric Oxide in Cirrhotic Rats

To examine the role and effect of nitric oxide synthase type Ⅱ(NOSⅡ) in cirrhotic rats, expression of NOSⅡ mRNA was detected by real time RT-PCR. The enzymatic activity of nitric oxide synthase and the circulating levels of NO, systemic and portal hemodynamics and quantification of cirrhosis were measured. Chinese traditional medicine was used to treat cirrhotic rats and the effect of NO was evaluated. Double-blind method was used in experiment. Our results showed the concentration of NO and the enzymatic activity of NOS increased markedly at all stages of cirrhosis and iNOSmRNA was strongly expressed. Meanwhile, the portal-venous-pressure (PVP) and portal-venous-flow (PVF) were significantly increased. NO, NOS and iNOSmRNA were positively correlated to the degree of hepatic fibrosis. Tetrandrine significantly inhibited NO production and the expression of iNOSmRNA. Our results suggested that increased hepatic expression of NOSⅡ is one of the important factors causing cirrhosis and portal hypertension. Tetrandrine can significantly ameliorate cirrhosis and portal hypertension.

Hemodynamic and antifibrotic effects of a selective liver nitric oxide donor V-PYRRO/NO in bile duct ligated rats

AIM: To assess whether a liver specific nitric oxide (NO) donor (V-PYRRO/NO) would prevent the development of portal hypertension and liver fibrosis in rats with bile duct ligation (BDL). METHODS: Treatment (placebo or V-PYRRO/NO 0.53 μmol/kg per hour) was administered i.v. to rats 2 d before BDL (D-2) and maintained until the day of hemodynamic measurement (D26). Intra-hepatic NO level was estimated by measuring liver cGMP level. Effects of V-PYRRO/NO on liver fibrosis and lipid peroxidation were also assessed. RESULTS: Compared to placebo treatment, V-PYRRO/ NO improved splanchnic hemodynamics in BDL rats: portal pressure was significantly reduced by 27% (P < 0.0001) and collateral circulation development was almost completely blocked (splenorenal shunt blood flow by 74%, P = 0.007). Moreover, V-PYRRO/NO significantly prevented liver fibrosis development in BDL rats (by 30% in hepatic hydroxyproline content and 31% in the area of fibrosis, P < 0.0001 respectively), this effect being probably due to a decrease in lipid peroxidation by 44% in the hepatic malondialdehyde level (P = 0.007). Interestingly, we observed a significant and expected increase in liver cGMP, without any systemic hemodynamic effects (mean arterial pressure, vascular systemic resistance and cardiac output) in both sham- operated and BDL rats treated with V-PYRRO/NO. This result is in accordance with studies on V-PYRRO/NO metabolism showing a specific release of NO in the liver.NO in BDL rats improved liver fibrosis and splanchnic hemodynamics without any noxious systemic hemo- dynamic effects.

Nitric oxide synthase distribution in esophageal mucosa and hemodynamic changes in rats with cirrhosis

AIM To observe the nitric oxide synthase (NOS) distribution in the esophageal mucosa andhemodynamic changes in cirrhotic rats.METHODS NOS distribution in the loweresophagus of rats with carbon tetrachlorideinduced cirrhosis was assessed by using NADPHdiaphorase (NADPH-d ) histochemical method.Concentration of NO in serum were measured byfluorometric assay. Mean arterial pressure(MAP), cardiac output (CO), cardiac index (CI),splanchnic vascular resistance (SVR ), andsplanchnic blood flow (SBF ) were alsodetermined using 5’CO-labeled microspheretechnique.RESULTS Intensity of NOS staining in theesophageal epithelium of cirrhotic rats wassignificantly stronger than that in controls.There was a NOS--positive staining area in theendothelia of esophageal submucosal vessels ofcirrhotic rats, but the NOS staining was negativein normal rats. NO concentration of serum incirrhotic rats were significantly higher incomparison with that of controls. Cirrhotic ratshad significantly lower MAP, SVR and higherSBF than those of the controls.CONCLUSION SPlanchnic hyperdynamiccirculatory state was observed in rats withcirrhosis. The endogenous NO may play animportant role in development of esophagealvarices and in changes of hemodynamics incirrhosis.

Nitric oxide and oxygen radicals induced apoptosis via bcl-2 and p53 pathway in hypoxia-reoxygenated cardiomyocytes

Neonatal rat cardiomyocytes were subjected to 24 h of hypoxia 95%N2/5%CO2 and 24 h of hypoxia plus 4 h of reoxygenation 95%O2/5%CO2. 24 h of hypoxia increased the levels of NO, --23NO/NO, TBARS and LDH. 24 h of hypoxia plus 4 h of reoxygenation decreased the levels of NO, --23NO/NO, but further increased TBARS and LDH. The hypoxia up-regulated the expression of bcl-2, p53 and p21/waf1/cip1 but the reoxygenation down-regulated the expression of bcl-2, and further up-regulated p53 and p21/waf1/cip1. The hypoxia increased cell apoptosis and reoxygena-tion further increased both apoptotic and necrotic cell death. NO, -23NO/NO, TBARS, DNA frag-mentation and cell apoptosis were enhanced by SNP and inhibited by L-NAME respectively. In addition, SOD/catalase down-regulated the expression of p53, p21/wafl/cipl and TBARS but up-regulated bcl-2 and increased indirectly the level of NO, --23NO/NO, and inhibited DNA frag-mentation. The results suggest that hypoxia-induced cell death is associated with the activation of NO, bcl-2 and p53 pathway, while hypoxia-reoxygenation induced cell death via the generation of reactive oxygen species and activation of p53 pathway. The present study clarified that NO may be an initiative signal to apoptotic cell death and the activation of bcl-2, p53 and p21/waf1/cip1 path-way in hypoxic and hypoxia-reoxygenated cardiomyocytes.

Inhaled nitric oxide as a salvage therapy for refractory hypoxemia in the post-transplantation period of hepatopulmonary syndrome:An explorative report of three cases

Liver transplantation(LT)is the only effective treatment for hepatopulmonary syndrome(HPS).Moreover,perioperative refractory hypoxemia(pRH)is a prevalent life-threatening condition and has extremely limited treatment options.Here,we report three patients with HPS who experienced pRH after LT and were consecutively treated with different salvage therapies,ephedrine inhalation,intravenous use of methylene blue with nitric oxide(NO)inhalation,and NO inhalation alone.The results showed that unresolved severe hypoxia may induce fatal morbidity such as early biliary leakage and acute kidney injury.Early initiation of NO inhalation,rather than ephedrine,can significantly improve oxygenation in patients with pRH and may help prevent hypoxia-related complications.Therefore,based on the response to these exploratory salvage treatments,we further demonstrate the unique ventilation-perfusion mismatch pathophysiology in specific lung regions during pRH in HPS.We propose that early inhalation of NO is an important treatment option to rescue severe hypoxia in patients with HPS during the perioperative period of LT.

Effect of sodium nitroprusside on hemodynamics of corpus cavernosum in Chinese

Aim: To study the effect of sodium nitroprusside (SNP) on the hemodynamics of corpus cavemosum in Chinese menwith erectile dysfunction (ED). Methods; In 68 ED patients receiving intracavemous injection (ICI) of SNP, thecavernous hemodynamics were studied by Doppler ultrasonography. Results: The peak flow velocity (PFV), theartery diameter (Ad), the mean velocity of arterial blood (MV) and the vein diameter (Vd) were significantly higherafter ICI of SNP than before ICI, but the end diastolic velocity (EDV) did not change significantly. Conclusion;The increase in Vd after SNP suggests that the venous outflow is not invariably decreased during penile erection.(Asian J Androl 2001 Dec; 3: 311 - 313)

Puerarin decreases hypoxia inducible factor-1 alpha in the hippocampus of vascular dementia rats

In this study, a rat vascular dementia model was established by permanent bilateral common carotid arterial occlusion. Rats were intraperitoneally injected with puerarin 3 days before modeling, for 45 successive days. Results demonstrated that in treated animals hippocampal structures were clear, nerve cells arranged neatly, and cytoplasm was rich in Nissl bodies. The number of cells positive for hypoxia inducible factor-1 alpha, erythropoietin and endothelial nitric oxide synthase was reduced; and the learning and memory abilities of rats were significantly improved. Our experimental findings indicate that puerarin can significantly improve learning and memory in a vascular dementia model, and that the underlying mechanism may be associated with the regulation of the expression of hypoxia inducible factor-1 alpha.

Microvesicles derived from hypoxia/reoxYgenation-treated human umbilical vein endothellal cells impair relaxation of rat thoracic aortic rings

Objective To investigate the effects of microvesicles(MVs) derived from hypoxia/reoxygenation(H/R)-treated human umbilical vein endothelial cells(HUVECs) on endothelium-dependent relaxation of rat thoracic aortic rings.Methods H/R injury model was established to induce HUVECs to release H/R-EMVs.H/R-EMVs from HUVECs were isolated by ultracentrifugation from the conditioned culture medium.H/R-EMVs were characterized using 1 urn latex beads and anti-PE-CD144 by flow cytometry.Thoracic aortic rings of rats were incubated with 2.5,5,10,20 μg/ml H/R-EMVs derived from H/R-treated HUVECs for 4 hours,and their endothelium-dependent relaxation in response to acetylcholine(ACh) or endothelium-independent relaxation in response to sodium nitroprusside(SNP) was recorded in vitro.The nitric oxide(NO) production of ACh-treated thoracic aortic rings of rats was measured using Griess reagent.The expression of endothelial NO synthase(eNOS) and phosphorylated eNOS(p-eNOS,Ser-1177) in the thoracic aortic rings of rats was detected by Western blotting.Furthermore,the levels of SOD and MDA in H/R-EMVs-treated thoracic aortic rings of rats were measured using SOD and MDA kit.Results H/R-EMVs were induced by H/R-treated HUVECs and isolated by ultracentrifugation.The membrane vesicles(< 1 urn) induced by H/R were CD144 positive.ACh-induced relaxation and NO production of rat thoracic aortic rings were impaired by H/R-EMVs treatment in a concentration-dependent manner(P<0.05,P<0.01).The expression of total eNOS(t-eNOS)was not affected by H/R-EMVs.However,the expression of p-eNOS decreased after treated with H/R-EMVs.The activity of SOD decreased and the level of MDA increased in H/R-EMVs treated rat thoracic aortic rings(P<0.01).Conclusion ACh induced endothelium-dependent relaxation of thoracic aortic rings of rats was impaired by H/R-EMVs in a concentration-dependent manner.The mechanisms included a decrease in NO production,p-eNOS expression and an increase in oxidative stress.

Effects of Salvia miltiorrhiza extracts on rat hypoxic pulmonary hypertension, heme oxygenase-1 and nitric oxide synthase

Objective To investigate the effects of Salvia miltiorrhiza (SM) extracts on the expression of heme oxygenase-1 (HO-1) and nitric oxide synthase (NOS) in small pulmonary arteries (SPAs) of rats with chronic hypoxia. Methods After two weeks of hypoxia, rats were treated with diltiazem, and small, median, and large doses of SM extracts. The lungs were tested for the expression and distribution of HO-1, endothelial NOS (eNOS) and inducible NOS (iNOS) by using immunohistochemistry and Western blot method. Results Median and large doses of SM extracts significantly reduced hypoxia-induced media thickening in the SPAs (similar with diltiazem), recovered repaired ultrastructure injury, decreased HO-1 and iNOS levels, and increased eNOS expression in the SPAs. Conclusions Median and large doses of SM extracts play significant roles in inhibiting structural remodeling in rats with hypoxic pulmonary hypertension. These effects might attribute to the suppression of HO-1 and iNOS, and the promotion of eNOS expression under the conditions of hypoxia.