Aim: To examine the effect of L-arginine, the substrate of nitric oxide (NO) synthase, on reproductive function ofmale rats. Methods: Male rats were gavaged with either L-arginine (100 or 200 mg·kg^(-1)·d^(-...Aim: To examine the effect of L-arginine, the substrate of nitric oxide (NO) synthase, on reproductive function ofmale rats. Methods: Male rats were gavaged with either L-arginine (100 or 200 mg·kg^(-1)·d^(-1)), D-arginine (200mg·kg^(-1)·d^(-1)) or vehicle (0.9% NaCl) for seven consecutive days. Their sexual behaviour and fertility were evaluat-ed using receptive females. Results: L-arginine (200 mg/kg) had no significant effect on sexual competence (interms of sexual arousal, libido, sexual vigour and sexual performance). In mating experiments, the higher dose of L-arginine effectively and reversibly inhibited fertility, whilst the lower dose and the inactive stereoisomer D-arginine hadno significant effect. The antifertility effect caused by L-arginine was due to a profound elevation in the preimplantationloss mediated possibly by impairment in epididymal sperm maturation, hyperactivated sperm motility and sperm capaci-tation. Conclusion: Elevated NO production may be detrimental to male fertility.展开更多
Purpose: The purpose of this study was to develop a method to quantitatively assess the effect of nitric oxide synthase (NOS) inhibition on tumor vascular activity using dynamic contrast-enhanced computed tomography (...Purpose: The purpose of this study was to develop a method to quantitatively assess the effect of nitric oxide synthase (NOS) inhibition on tumor vascular activity using dynamic contrast-enhanced computed tomography (DCE-CT) and to investigate its usefulness using animal experiments. Mate-rials and Methods: The DCE-CT studies were performed in anesthetized Fisher rats bearing tumors using a 4-row multi-slice CT. The scanning started 4 s before a bolus injection of iodinated contrast agent (CA) (150 mgI/kg) from the tail vein using an automatic injector and lasted 60 s at 1-s in-tervals. The contrast enhancement (CE) images were generated by subtracting the CT images before and after the administration of CA. First, the DCE-CT studies were performed before and 15, 30, and 45 min after administration of N-nitro-L-arginine (L-NNA) (1, 3, and 10 mg/kg) or vehicle, and the relative CE values were calculated by normalizing the CE image at each time point by that obtained from the first DCE-CT study. Second, we investigated the case when L-arginine (L-ARG) (200 mg/kg) and L-NNA (1, 3, and 10 mg/kg) were administered after the first and second DCE-CT studies, respectively. Third, we investigated the case when L-NNA (1, 3, and 10 mg/kg) and L-ARG (200 mg/kg) were administered after the first and second DCE-CT studies, respectively. Finally, we investigated the case when L-NNA (1, 3, and 10 mg/kg) and L-ARG (200 mg/kg) were administered simultaneously after the first DCE-CT study. Results: The relative CE value significantly decreased after L-NNA administration in a dose-dependent manner (p-values = 0.0074 and <0.0001 for 0 vs. 3 mg/kg and 0 vs. 10 mg/kg, respectively, at 15 min, 0.0003 and <0.0001 for 0 vs. 3 mg/kg and 0 vs. 10 mg/kg, respectively, at 30 min, and 0.0367 and 0.0004 for 0 vs. 3 mg/kg and 0 vs. 10 mg/kg, respectively, at 45 min). When L-ARG was administered prior to the administration of 1 mg/kg L-NNA, the relative CE value at 45 min was significantly higher than that at 15 min. When L-ARG was administered after L-NNA administration, there was no significant difference between the relative CE values at 15 min and 45 min. These results suggest that when using L-NNA in combination with L-ARG, their effect on tumor vascular activity differs depending on the order of their administration. When L-NNA and L-ARG were administered simultaneously, there was a tendency for the relative CE value to be higher than that when only L-NNA was administered, at all injected doses of L-NNA. Conclusion: Our method using DCE-CT is useful for monitoring the effect of NOS inhibition on tumor vascular activity and for determining the optimal injected dose and timing of NOS inhibitors for anticancer therapy.展开更多
Background and Objectives: Exhaled nitric oxide (NO) is decreased by smoking while oxides of nitrogen such as nitrites/nitrates (NOx) are increased. It was hypothesised that in vitro cigarette smoke extract (CSE) woul...Background and Objectives: Exhaled nitric oxide (NO) is decreased by smoking while oxides of nitrogen such as nitrites/nitrates (NOx) are increased. It was hypothesised that in vitro cigarette smoke extract (CSE) would either inhibit NO generation by increasing the NO synthase inhibitor, NG, NG-dimethyl-L-arginine (ADMA) or increase NOx levels via an oxidation pathway, which in turn could be inhibited by the antioxidant N-acetylcysteine NAC. Methods: Transformed airway cells (A549) were cultured with control medium, 1.0% CSE in culture medium, or 0.8 mM NAC with 1.0% CSE. Baseline L-arginine, NOx and ADMA levels were measured in the media. Conditioned media were then sampled at 1hour, 6 hours, 24 hours, 48 hours and 72 hours after incubation. Results: CSE induced significantly higher NOx levels (mean (SD) peak increase of 135.8 (126.6)% after incubation for 6 hours (p x which was partially reversed by NAC pre-treatment. ADMA levels were also increased after CSE exposure, suggesting that it activates the NO pathway via oxidative-stress while inhibition probably occurs via both ADMA and NOS.展开更多
Exhaled breath nitric oxide （NO） is an accepted asthma biomarker. Lung concentrations of NO and its amino acid precursor, L-arginine, are regulated by the relative expressions of the NO synthase （NOS） and arginase...Exhaled breath nitric oxide （NO） is an accepted asthma biomarker. Lung concentrations of NO and its amino acid precursor, L-arginine, are regulated by the relative expressions of the NO synthase （NOS） and arginase isoforms. Increased expression of arginase I and NOS2 occurs in murine models of allergic asthma and in biopsies of asthmatic airways. Although clinical trials involving the inhibition of NO-producing enzymes have shown mixed results, small molecule arginase inhibitors have shown potential as a therapeutic intervention in animal and cell culture models. Their transition to clinical trials is hampered by concerns regarding their safety and potential tox- icity. In this review, we discuss the paradigm of arginase and NOS competition for their substrate L-arginine in the asthmatic airway. We address the functional role of L-arginine in inflammation and the potential role of arginase inhibitors as therapeutics.展开更多
BACKGROUND: Although the use of non-heart beating donors (NHBDs) could bridge the widening gap between organ demand and supply, its application to liver transplantation is limited due to the high incidence of primary ...BACKGROUND: Although the use of non-heart beating donors (NHBDs) could bridge the widening gap between organ demand and supply, its application to liver transplantation is limited due to the high incidence of primary graft loss. Prevention of liver injury in NHBDs will benefit the results of transplantation. This study was conducted to evaluate the protective effects of L-arginine on liver grafts from NHBDs. METHODS: One hundred and four Wistar rats were randomly divided into 7 groups: normal control (n=8) controls 1, 2 and 3 (C-1, C-2, C-3, n=16), and experimental 1, 2 and 3 (E-1, E-2, E-3, n=16). For groups C-1 and E-1, C-2 and E-2, and C-3 and E-3, the warm ischemia time was 0, 30, and 45 minutes, respectively. Liver grafts were flushed with and preserved in 4 degrees C Euro-collins solution containing 1 mmol/L L-arginine for 1 hour in each experimental group. Recipients of each experimental group were injected with L-arginine (10 mg/kg body weight) by tail vein 10 minutes before portal vein reperfusion. Donors and recipients of each experimental control group were treated with normal saline. Then transplantation was performed. At 1, 3, and 24 hours after portal vein reperfusion, blood samples were obtained to determine the levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), nitric oxide (NO) and plasma endothelin (ET). At 3 hours after portal vein reperfusion, grafts samples were fixed in 2.5% glutaraldehyde for electron microscopic observation. RESULTS: At I hour after portal vein reperfusion, the levels of NO in groups E-1, E-2, E-3 and C-1, C-2, C-3 were lower, while the levels of plasma ET, serum ALT and AST were higher than those in the normal control group (P<0.05). At 1, 3, and 24 hours, the levels of NO in groups E-1, E-2, E-3 were higher, while the levels of plasma ET, serum ALT and AST were lower than those in the corresponding control groups (C-1, C-2, C-3) (P<0.05). The levels of NO in groups C-2 and C-3 were lower than in group C-1 (P<0.05), and the level of NO in group C-3 was lower than in group C-2 (P<0.05). At 1, 3 and 24 hours, the levels of plasma ET, serum ALT, and AST in groups E-1, E-2, E-3 were lower than those in the corresponding control groups (C-1, C-2, C-3) (P<0.05). The levels of plasma ET, serum ALT, and AST were lower in group C-3 than in groups C-1 and C-2 (P<0.05). Pathological changes in groups E-1, E-2, E-3 were milder than those in the corresponding experimental control groups (C-1, C-2, C-3). CONCLUSIONS: The imbalance between NO and ET plays an important role in the development of ischemia-reperfusion injury of liver grafts from NHBDs. L-arginine can attenuate injury in liver grafts from NHBDs by improving the balance between NO and ET.展开更多
The influence of L-arginine on endothelial nitric oxide synthase （eNOS） and cyclooxygenase 2 （COX2） was observed in experimental pulmonary thromboembolism and the action mechanism on pulmonary thromboembolism was ...The influence of L-arginine on endothelial nitric oxide synthase （eNOS） and cyclooxygenase 2 （COX2） was observed in experimental pulmonary thromboembolism and the action mechanism on pulmonary thromboembolism was explored. Wistar rats were randomly divided into control group, model group and treatment group. Pulmonary thromboembolism models were established by auto-blood back transfusion, and L-Arg 100 mg/kg was intraperitoneally injected after successful model preparation. The animals were sacrificed at 3 h, 1 day, 3 days and 7 days after embolism. Plasma NO, TXB2 and 6-Keto-PGF1 α were detected. The expression of eNOS and COX2 protein and mRNA in pulmonary tissues was detected by immunohistochemistry and RT-PCR respectively. The results showed that pulmonary thrombosis could be seen post pulmonary embolism and inflammatory reaction was significant. Plasma NO was decreased （P〈0.01）, and the levels of TXB2, 6-Keto-PGF1α and T/P ratio were all elevated. The expression of eNOS protein and mRNA in the pulmonary tissue was down-regulated （P〈0.05）, while that of COX2 protein and mRNA was upregulated （P〈0.01）. In treatment group, the level of NO was increased, the levels of TXB2 and T/P ratio were decreased, but the level of 6-Keto-PGF1 α was increased. The expression of eNOS protein and mRNA in pulmonary tissue was upregulated （P〈0.05）, while that of COX2 protein and mRNA was down-regulated （P〈0.05）. In conclusion, L-arginine can educe the role of pulmonary tissue protection through up-regulating the expression of intra-pulmonary NOS and down -regulating COX2 in pulmonary thromboembolism.展开更多
Objective:To study the effects of NO precursor L-arginine on the recovery of traumatic facial paralysisin rats and the changes of constitutive NOS/inducible NOS in the facial nucleus. Methods: A small dose of L-argini...Objective:To study the effects of NO precursor L-arginine on the recovery of traumatic facial paralysisin rats and the changes of constitutive NOS/inducible NOS in the facial nucleus. Methods: A small dose of L-arginine was intraperitoneally injected into rats with facial paralysis, and the recovery of facial paralysis was observedat different time point. Immunohistochemical ABC method was used to study the changes of NOS positive neuronsin facial nucleus. Results: The recovery of facial paralysis in L-arginine chronic treatment group was faster thanthat in the experimental control group and the constitutive NOS immunoreactivity was intensive in facial nucleus,but the inducible NOS immunoreactivity had no apparent difference in comparison with that of the experimentalcontrol group. Conclusion: L-arginine chronic treatment can increase the constitutive NOS expression in facial nucleus and prornote the recovery of traumatic facial paralysis.展开更多
目的探讨L-精氨酸(L-arginine,L-Arg)对心肌细胞血管紧张素Ⅱ受体(angiotensin Ⅱ receptor,ATR)及丝裂原活化蛋白激酶(mitogen-activated protein kinase,MAPK)表达的影响,进而阐述L-Arg对病理性心肌肥大的影响作用及相关机制。方法用...目的探讨L-精氨酸(L-arginine,L-Arg)对心肌细胞血管紧张素Ⅱ受体(angiotensin Ⅱ receptor,ATR)及丝裂原活化蛋白激酶(mitogen-activated protein kinase,MAPK)表达的影响,进而阐述L-Arg对病理性心肌肥大的影响作用及相关机制。方法用血管紧张素Ⅱ(angiotensinⅡ,ATⅡ)、ATR抑制剂、L-Arg和(或)L-NAME(L-硝基精氨酸甲酯)分别作用于心肌细胞,然后以[3H]-亮氨酸参入法检测细胞蛋白合成速率、比色法检测一氧化氮(NO)生成量、RT-PCR及Western blot检测ATR及p38MAPK的表达水平。结果①给予L-Arg可缓解ATⅡ引起的心肌细胞NO合成量下降,减弱血管紧张素Ⅱ-1型受体(angiotensin receptor type1,ATR1)表达及下调p38MAPK蛋白磷酸化水平,并降低心肌细胞蛋白合成速率给予ATⅡ或L-Arg均未影响血管紧张素Ⅱ-2受体(angiotensin receptor type 2,ATP2)的表达水平;②心肌ATR1表达水平及p38MAPK蛋白磷酸化水平均与NO合成量之间存在线性负相关。多元逐步回归分析显示在ATR1与ATR2中,仅ATR1的表达水平与p38MAPK蛋白磷酸化水平之间存在回归关系。结论①L-Arg可致心肌细胞NO合成量增加,后者可抑制ATR1介导的p38MAPK蛋白磷酸化水平上调,进而抑制心肌细胞肥大反应;②ATR2未参与上述过程。展开更多
文摘Aim: To examine the effect of L-arginine, the substrate of nitric oxide (NO) synthase, on reproductive function ofmale rats. Methods: Male rats were gavaged with either L-arginine (100 or 200 mg·kg^(-1)·d^(-1)), D-arginine (200mg·kg^(-1)·d^(-1)) or vehicle (0.9% NaCl) for seven consecutive days. Their sexual behaviour and fertility were evaluat-ed using receptive females. Results: L-arginine (200 mg/kg) had no significant effect on sexual competence (interms of sexual arousal, libido, sexual vigour and sexual performance). In mating experiments, the higher dose of L-arginine effectively and reversibly inhibited fertility, whilst the lower dose and the inactive stereoisomer D-arginine hadno significant effect. The antifertility effect caused by L-arginine was due to a profound elevation in the preimplantationloss mediated possibly by impairment in epididymal sperm maturation, hyperactivated sperm motility and sperm capaci-tation. Conclusion: Elevated NO production may be detrimental to male fertility.
文摘Purpose: The purpose of this study was to develop a method to quantitatively assess the effect of nitric oxide synthase (NOS) inhibition on tumor vascular activity using dynamic contrast-enhanced computed tomography (DCE-CT) and to investigate its usefulness using animal experiments. Mate-rials and Methods: The DCE-CT studies were performed in anesthetized Fisher rats bearing tumors using a 4-row multi-slice CT. The scanning started 4 s before a bolus injection of iodinated contrast agent (CA) (150 mgI/kg) from the tail vein using an automatic injector and lasted 60 s at 1-s in-tervals. The contrast enhancement (CE) images were generated by subtracting the CT images before and after the administration of CA. First, the DCE-CT studies were performed before and 15, 30, and 45 min after administration of N-nitro-L-arginine (L-NNA) (1, 3, and 10 mg/kg) or vehicle, and the relative CE values were calculated by normalizing the CE image at each time point by that obtained from the first DCE-CT study. Second, we investigated the case when L-arginine (L-ARG) (200 mg/kg) and L-NNA (1, 3, and 10 mg/kg) were administered after the first and second DCE-CT studies, respectively. Third, we investigated the case when L-NNA (1, 3, and 10 mg/kg) and L-ARG (200 mg/kg) were administered after the first and second DCE-CT studies, respectively. Finally, we investigated the case when L-NNA (1, 3, and 10 mg/kg) and L-ARG (200 mg/kg) were administered simultaneously after the first DCE-CT study. Results: The relative CE value significantly decreased after L-NNA administration in a dose-dependent manner (p-values = 0.0074 and <0.0001 for 0 vs. 3 mg/kg and 0 vs. 10 mg/kg, respectively, at 15 min, 0.0003 and <0.0001 for 0 vs. 3 mg/kg and 0 vs. 10 mg/kg, respectively, at 30 min, and 0.0367 and 0.0004 for 0 vs. 3 mg/kg and 0 vs. 10 mg/kg, respectively, at 45 min). When L-ARG was administered prior to the administration of 1 mg/kg L-NNA, the relative CE value at 45 min was significantly higher than that at 15 min. When L-ARG was administered after L-NNA administration, there was no significant difference between the relative CE values at 15 min and 45 min. These results suggest that when using L-NNA in combination with L-ARG, their effect on tumor vascular activity differs depending on the order of their administration. When L-NNA and L-ARG were administered simultaneously, there was a tendency for the relative CE value to be higher than that when only L-NNA was administered, at all injected doses of L-NNA. Conclusion: Our method using DCE-CT is useful for monitoring the effect of NOS inhibition on tumor vascular activity and for determining the optimal injected dose and timing of NOS inhibitors for anticancer therapy.
文摘Background and Objectives: Exhaled nitric oxide (NO) is decreased by smoking while oxides of nitrogen such as nitrites/nitrates (NOx) are increased. It was hypothesised that in vitro cigarette smoke extract (CSE) would either inhibit NO generation by increasing the NO synthase inhibitor, NG, NG-dimethyl-L-arginine (ADMA) or increase NOx levels via an oxidation pathway, which in turn could be inhibited by the antioxidant N-acetylcysteine NAC. Methods: Transformed airway cells (A549) were cultured with control medium, 1.0% CSE in culture medium, or 0.8 mM NAC with 1.0% CSE. Baseline L-arginine, NOx and ADMA levels were measured in the media. Conditioned media were then sampled at 1hour, 6 hours, 24 hours, 48 hours and 72 hours after incubation. Results: CSE induced significantly higher NOx levels (mean (SD) peak increase of 135.8 (126.6)% after incubation for 6 hours (p x which was partially reversed by NAC pre-treatment. ADMA levels were also increased after CSE exposure, suggesting that it activates the NO pathway via oxidative-stress while inhibition probably occurs via both ADMA and NOS.
基金supported by the following grants:National Institute of Environmental Health Sciences funded training program in Environmental Health Sciences (No.T32 ES007058-33) to Jennifer M.Bratt,CTSC K12 Award (No.UL1RR024146)KL2RR024144 to Amir A.Zekithe American Asthma Foundation to Nicholas J.Kenyon.
文摘Exhaled breath nitric oxide （NO） is an accepted asthma biomarker. Lung concentrations of NO and its amino acid precursor, L-arginine, are regulated by the relative expressions of the NO synthase （NOS） and arginase isoforms. Increased expression of arginase I and NOS2 occurs in murine models of allergic asthma and in biopsies of asthmatic airways. Although clinical trials involving the inhibition of NO-producing enzymes have shown mixed results, small molecule arginase inhibitors have shown potential as a therapeutic intervention in animal and cell culture models. Their transition to clinical trials is hampered by concerns regarding their safety and potential tox- icity. In this review, we discuss the paradigm of arginase and NOS competition for their substrate L-arginine in the asthmatic airway. We address the functional role of L-arginine in inflammation and the potential role of arginase inhibitors as therapeutics.
基金a grant from the Science & Technology Development Foundation of Guangdong Health Bureau(No.2006345).
文摘BACKGROUND: Although the use of non-heart beating donors (NHBDs) could bridge the widening gap between organ demand and supply, its application to liver transplantation is limited due to the high incidence of primary graft loss. Prevention of liver injury in NHBDs will benefit the results of transplantation. This study was conducted to evaluate the protective effects of L-arginine on liver grafts from NHBDs. METHODS: One hundred and four Wistar rats were randomly divided into 7 groups: normal control (n=8) controls 1, 2 and 3 (C-1, C-2, C-3, n=16), and experimental 1, 2 and 3 (E-1, E-2, E-3, n=16). For groups C-1 and E-1, C-2 and E-2, and C-3 and E-3, the warm ischemia time was 0, 30, and 45 minutes, respectively. Liver grafts were flushed with and preserved in 4 degrees C Euro-collins solution containing 1 mmol/L L-arginine for 1 hour in each experimental group. Recipients of each experimental group were injected with L-arginine (10 mg/kg body weight) by tail vein 10 minutes before portal vein reperfusion. Donors and recipients of each experimental control group were treated with normal saline. Then transplantation was performed. At 1, 3, and 24 hours after portal vein reperfusion, blood samples were obtained to determine the levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), nitric oxide (NO) and plasma endothelin (ET). At 3 hours after portal vein reperfusion, grafts samples were fixed in 2.5% glutaraldehyde for electron microscopic observation. RESULTS: At I hour after portal vein reperfusion, the levels of NO in groups E-1, E-2, E-3 and C-1, C-2, C-3 were lower, while the levels of plasma ET, serum ALT and AST were higher than those in the normal control group (P<0.05). At 1, 3, and 24 hours, the levels of NO in groups E-1, E-2, E-3 were higher, while the levels of plasma ET, serum ALT and AST were lower than those in the corresponding control groups (C-1, C-2, C-3) (P<0.05). The levels of NO in groups C-2 and C-3 were lower than in group C-1 (P<0.05), and the level of NO in group C-3 was lower than in group C-2 (P<0.05). At 1, 3 and 24 hours, the levels of plasma ET, serum ALT, and AST in groups E-1, E-2, E-3 were lower than those in the corresponding control groups (C-1, C-2, C-3) (P<0.05). The levels of plasma ET, serum ALT, and AST were lower in group C-3 than in groups C-1 and C-2 (P<0.05). Pathological changes in groups E-1, E-2, E-3 were milder than those in the corresponding experimental control groups (C-1, C-2, C-3). CONCLUSIONS: The imbalance between NO and ET plays an important role in the development of ischemia-reperfusion injury of liver grafts from NHBDs. L-arginine can attenuate injury in liver grafts from NHBDs by improving the balance between NO and ET.
文摘The influence of L-arginine on endothelial nitric oxide synthase （eNOS） and cyclooxygenase 2 （COX2） was observed in experimental pulmonary thromboembolism and the action mechanism on pulmonary thromboembolism was explored. Wistar rats were randomly divided into control group, model group and treatment group. Pulmonary thromboembolism models were established by auto-blood back transfusion, and L-Arg 100 mg/kg was intraperitoneally injected after successful model preparation. The animals were sacrificed at 3 h, 1 day, 3 days and 7 days after embolism. Plasma NO, TXB2 and 6-Keto-PGF1 α were detected. The expression of eNOS and COX2 protein and mRNA in pulmonary tissues was detected by immunohistochemistry and RT-PCR respectively. The results showed that pulmonary thrombosis could be seen post pulmonary embolism and inflammatory reaction was significant. Plasma NO was decreased （P〈0.01）, and the levels of TXB2, 6-Keto-PGF1α and T/P ratio were all elevated. The expression of eNOS protein and mRNA in the pulmonary tissue was down-regulated （P〈0.05）, while that of COX2 protein and mRNA was upregulated （P〈0.01）. In treatment group, the level of NO was increased, the levels of TXB2 and T/P ratio were decreased, but the level of 6-Keto-PGF1 α was increased. The expression of eNOS protein and mRNA in pulmonary tissue was upregulated （P〈0.05）, while that of COX2 protein and mRNA was down-regulated （P〈0.05）. In conclusion, L-arginine can educe the role of pulmonary tissue protection through up-regulating the expression of intra-pulmonary NOS and down -regulating COX2 in pulmonary thromboembolism.
文摘Objective:To study the effects of NO precursor L-arginine on the recovery of traumatic facial paralysisin rats and the changes of constitutive NOS/inducible NOS in the facial nucleus. Methods: A small dose of L-arginine was intraperitoneally injected into rats with facial paralysis, and the recovery of facial paralysis was observedat different time point. Immunohistochemical ABC method was used to study the changes of NOS positive neuronsin facial nucleus. Results: The recovery of facial paralysis in L-arginine chronic treatment group was faster thanthat in the experimental control group and the constitutive NOS immunoreactivity was intensive in facial nucleus,but the inducible NOS immunoreactivity had no apparent difference in comparison with that of the experimentalcontrol group. Conclusion: L-arginine chronic treatment can increase the constitutive NOS expression in facial nucleus and prornote the recovery of traumatic facial paralysis.
