-
American Journal of Physiology. Heart... Mar 2016The proposed mechanistic link between the age-related attenuation in vascular function and free radicals is an attractive hypothesis; however, direct evidence of free...
The proposed mechanistic link between the age-related attenuation in vascular function and free radicals is an attractive hypothesis; however, direct evidence of free radical attenuation and a concomitant improvement in vascular function in the elderly is lacking. Therefore, this study sought to test the hypothesis that ascorbic acid (AA), administered intra-arterially during progressive handgrip exercise, improves brachial artery (BA) vasodilation in a nitric oxide (NO)-dependent manner, by mitigating free radical production. BA vasodilation (Doppler ultrasound) and free radical outflow [electron paramagnetic resonance (EPR) spectroscopy] were measured in seven healthy older adults (69 ± 2 yr) during handgrip exercise at 3, 6, 9, and 12 kg (∼13-52% of maximal voluntary contraction) during the control condition and nitric oxide synthase (NOS) inhibition via N(G)-monomethyl-L-arginine (L-NMMA), AA, and coinfusion of l-NMMA + AA. Baseline BA diameter was not altered by any of the treatments, while L-NMMA and L-NMMA + AA diminished baseline BA blood flow and shear rate. AA improved BA dilation compared with control at 9 kg (control: 6.5 ± 2.2%, AA: 10.9 ± 2.5%, P = 0.01) and 12 kg (control: 9.5 ± 2.7%, AA: 15.9 ± 3.7%, P < 0.01). NOS inhibition blunted BA vasodilation compared with control and when combined with AA eliminated the AA-induced improvement in BA vasodilation. Free radical outflow increased with exercise intensity but, interestingly, was not attenuated by AA. Collectively, these results indicate that AA improves BA vasodilation in the elderly during handgrip exercise through an NO-dependent mechanism; however, this improvement appears not to be the direct consequence of attenuated free radical outflow from the forearm.
Topics: Aged; Ascorbic Acid; Brachial Artery; Enzyme Inhibitors; Exercise; Female; Free Radicals; Hand Strength; Humans; Infusions, Intra-Arterial; Male; Nitric Oxide; Nitric Oxide Synthase; Regional Blood Flow; Vasodilation; omega-N-Methylarginine
PubMed: 26801312
DOI: 10.1152/ajpheart.00817.2015 -
American Journal of Physiology. Heart... Mar 2016We tested the hypothesis that women exhibit greater vasodilator responses to β-adrenoceptor stimulation compared with men. We further hypothesized women exhibit a...
We tested the hypothesis that women exhibit greater vasodilator responses to β-adrenoceptor stimulation compared with men. We further hypothesized women exhibit a greater contribution of nitric oxide synthase and cyclooxygenase to β-adrenergic-mediated vasodilation compared with men. Forearm blood flow (Doppler ultrasound) was measured in young men (n = 29, 26 ± 1 yr) and women (n = 33, 25 ± 1 yr) during intra-arterial infusion of isoproterenol (β-adrenergic agonist). In subset of subjects, isoproterenol responses were examined before and after local inhibition of nitric oxide synthase [N(G)-monomethyl-l-arginine (l-NMMA); 6 male/10 female] and/or cyclooxygenase (ketorolac; 5 male/5 female). Vascular conductance (blood flow ÷ mean arterial pressure) was calculated to assess vasodilation. Vascular conductance increased with isoproterenol infusion (P < 0.01), and this effect was not different between men and women (P = 0.41). l-NMMA infusion had no effect on isoproterenol-mediated dilation in men (P > 0.99) or women (P = 0.21). In contrast, ketorolac infusion markedly increased isoproterenol-mediated responses in both men (P < 0.01) and women (P = 0.04) and this rise was lost with subsequent l-NMMA infusion (men, P < 0.01; women, P < 0.05). β-Adrenergic vasodilation is not different between men and women and sex differences in the independent contribution of nitric oxide synthase and cyclooxygenase to β-mediated vasodilation are not present. However, these data are the first to demonstrate β-adrenoceptor activation of cyclooxygenase suppresses nitric oxide synthase signaling in human forearm microcirculation and may have important implications for neurovascular control in both health and disease.
Topics: Adrenergic beta-Agonists; Adult; Cyclooxygenase Inhibitors; Enzyme Inhibitors; Female; Forearm; Humans; Infusions, Intra-Arterial; Isoproterenol; Ketorolac; Male; Microcirculation; Nitric Oxide Synthase; Prostaglandin-Endoperoxide Synthases; Sex Factors; Ultrasonography, Doppler; Vasodilation; omega-N-Methylarginine
PubMed: 26747505
DOI: 10.1152/ajpheart.00886.2015 -
Molecular Medicine Reports Feb 2016Spinal nitric oxide is involved in the mechanisms of pain generation and transmission during inflammatory and neuropathic pain. The aim of the present study was to...
Spinal nitric oxide is involved in the mechanisms of pain generation and transmission during inflammatory and neuropathic pain. The aim of the present study was to explore the role of spinal nitric oxide in the development of bone cancer pain. 2 x 10(5) osteosarcoma cells were implanted into the intramedullary space of right femurs of C3H/HeJ mice to induce a model of ongoing bone cancer. Polymerase chain reaction and immunohistochemical analyses were performed to assess the expression of neuronal nitric oxide synthase (nNOS) and inducible (i)NOS in the spinal cord following inoculation. The results showed that inoculation of osteosarcoma cells induced progressive bone cancer, accompanied with pain-associated behavior. The levels of nNOS mRNA in the spinal cord of tumor mice began to increase at day 10 and then decreased to the level in sham mice at day 14, while iNOS mRNA markedly increased in the tumor group at days 10 and 14. Immunohistochemical analysis showed that nNOS- and iNOS-positive neurons were mainly located in the superficial dorsal horn and around the central canal of the L3-L5 spinal cord. Intrathecal injection of 50 µg NOS inhibitor NG-monomethyl-L-arginine (L-NMMA) attenuated cancer-evoked pain behaviors at day 14. These findings indicated that an upregulation of nNOS and iNOS in the spinal cord is associated with bone cancer pain and suggests that exogenously administered L-NMMA may have beneficial effects to alleviate bone cancer pain.
Topics: Animals; Bone Neoplasms; Cell Line, Tumor; Femur; Gene Expression Regulation; Humans; Injections, Spinal; Mice; Neuralgia; Neurons; Nitric Oxide; Nitric Oxide Synthase Type I; Nitric Oxide Synthase Type II; Osteosarcoma; Spinal Cord; omega-N-Methylarginine
PubMed: 26648027
DOI: 10.3892/mmr.2015.4647 -
Cancer Immunology, Immunotherapy : CII Dec 2015The expansion of myeloid-derived suppressor cells (MDSCs) and its correlation with advanced disease stage have been shown in solid cancers. Here, we investigated the...
The expansion of myeloid-derived suppressor cells (MDSCs) and its correlation with advanced disease stage have been shown in solid cancers. Here, we investigated the functional features and clinical significance of MDSCs in extranodal NK/T cell lymphoma (ENKL). A higher percentage of circulating HLA-DR(-)CD33(+)CD11b(+) MDSCs was observed in ENKL patients than in healthy controls (P < 0.05, n = 32) by flow cytometry analysis. These MDSCs from ENKL patients (ENKL-MDSCs) consisted of CD14(+) monocytic (Mo-MDSCs, >60 %) and CD15(+) granulocytic (PMN-MDSCs, <20 %) MDSCs. Furthermore, these ENKL-MDSCs expressed higher levels of Arg-1, iNOS and IL-17 compared to the levels of MDSCs from healthy donors, and they expressed moderate levels of TGFβ and IL-10 but lower levels of CD66b. The ENKL-MDSCs strongly suppressed the anti-CD3-induced allogeneic and autologous CD4 T cell proliferation (P < 0.05), but they only slightly suppressed CD8 T cell proliferation (P > 0.05). Interestingly, ENKL-MDSCs inhibited the secretion of IFNγ but promoted IL-10, IL-17 and TGFβ secretion as well as Foxp3 expression in T cells. The administration of inhibitors of iNOS, Arg-1 and ROS significantly reversed the suppression of anti-CD3-induced T cell proliferation by MDSCs (P < 0.05). Importantly, based on multivariate Cox regression analysis, the HLA-DR(-)CD33(+)CD11b(+) cells and CD14(+) Mo-MDSCs were independent predictors for disease-free survival (DFS, P = 0.013 and 0.016) and overall survival (OS, P = 0.017 and 0.027). Overall, our results identified for the first time that ENKL-MDSCs (mainly Mo-MDSCs) have a prognostic value for patients and a suppressive function on T cell proliferation.
Topics: Acetylcysteine; Adolescent; Adult; Aged; Arginine; CD4-Positive T-Lymphocytes; CD8-Positive T-Lymphocytes; Cell Proliferation; Cytokines; Enzyme Inhibitors; Female; Free Radical Scavengers; Gene Expression Regulation, Neoplastic; Humans; Lymphocyte Activation; Lymphoma, Extranodal NK-T-Cell; Male; Middle Aged; Myeloid Cells; Nitric Oxide; Reactive Oxygen Species; Young Adult; omega-N-Methylarginine
PubMed: 26497849
DOI: 10.1007/s00262-015-1765-6 -
Sheng Li Xue Bao : [Acta Physiologica... Oct 2015The aim of this study was to explore the mechanism of the nervous system lesions induced by formaldehyde (FA). Male Balb/c mice were exposed to gaseous formaldehyde for...
The aim of this study was to explore the mechanism of the nervous system lesions induced by formaldehyde (FA). Male Balb/c mice were exposed to gaseous formaldehyde for 7 days (8 h/d) with three different concentrations (0, 0.5 and 3.0 mg/m(3)). A group of animals injected with the nitric oxide synthase inhibitor L-NMMA (0.01 mL/g) was also set and exposed to 3.0 mg/m(3) FA. The concentrations of cAMP, cGMP, NO and the activity of NOS in cerebral cortex, hippocampus and brain stem were determined by corresponding assay kits. The results showed that, compared with the control (0 mg/m(3) FA) group, the cAMP contents in cerebral cortex and brain stem were significantly increased in 0.5 mg/m(3) FA group (P < 0.05), but decreased in 3.0 mg/m(3) FA group (P < 0.05); The concentration of cAMP in hippocampus was significantly decreased in 3.0 mg/m(3) FA group (P < 0.05). In comparison with the control group, L-NMMA group showed unchanged cAMP contents and NOS activities in different brain regions, but showed increased cGMP contents in hippocampus and NO contents in cerebral cortex (P < 0.05). In addition, compared with 3.0 mg/m(3) FA group, L-NMMA group showed increased contents of cAMP and reduced NOS activities in different brain regions, as well as significantly decreased cGMP contents in cerebral cortex and brain stem and NO content in brain stem. These results suggest that the toxicity of FA on mouse nervous system is related to NO/cGMP and cAMP signaling pathways.
Topics: Animals; Brain Stem; Cerebral Cortex; Cyclic AMP; Cyclic GMP; Formaldehyde; Hippocampus; Male; Mice; Mice, Inbred BALB C; Nitric Oxide; Nitric Oxide Synthase; omega-N-Methylarginine
PubMed: 26490067
DOI: No ID Found -
Acta Medica Okayama 2015Lung hyperpermeability affects the development of acute respiratory distress syndrome (ARDS), but therapeutic strategies for the control of microvascular permeability... (Comparative Study)
Comparative Study
Inhibitory Effects of Edaravone, a Free Radical Scavenger, on Cytokine-induced Hyperpermeability of Human Pulmonary Microvascular Endothelial Cells:A Comparison with Dexamethasone and Nitric Oxide Synthase Inhibitor.
Lung hyperpermeability affects the development of acute respiratory distress syndrome (ARDS), but therapeutic strategies for the control of microvascular permeability have not been established. We examined the effects of edaravone, dexamethasone, and N-monomethyl-L-arginine (L-NMMA) on permeability changes in human pulmonary microvascular endothelial cells (PMVEC) under a hypercytokinemic state. Human PMVEC were seeded in a Boyden chamber. After monolayer confluence was achieved, the culture media were replaced respectively by culture media containing edaravone, dexamethasone, and L-NMMA. After 24-h incubation, the monolayer was stimulated with tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β). Fluorescein-labeled dextran was added. Then the trans-human PMVEC leak was measured. Expressions of vascular endothelial-cadherin (VE-cadherin) and zonula occludens-1 protein (ZO-1) were evaluated using real-time quantitative polymerase chain reaction and immunofluorescence microscopy. The results showed that TNF-α+IL-1β markedly increased pulmonary microvascular permeability. Pretreatment with edaravone, dexamethasone, or L-NMMA attenuated the hyperpermeability and inhibited the cytokine-induced reduction of VE-cadherin expression on immunofluorescence staining. Edaravone and dexamethasone increased the expression of ZO-1 at both the mRNA and protein levels. Edaravone and dexamethasone inhibited the permeability changes of human PMVEC, at least partly through an enhancement of VE-cadherin. Collectively, these results suggest a potential therapeutic approach for intervention in patients with ARDS.
Topics: Antigens, CD; Antipyrine; Cadherins; Capillary Permeability; Cells, Cultured; Cytokines; Dexamethasone; Edaravone; Endothelial Cells; Free Radical Scavengers; Humans; Intercellular Adhesion Molecule-1; Nitric Oxide Synthase; Zonula Occludens-1 Protein; omega-N-Methylarginine
PubMed: 26490025
DOI: 10.18926/AMO/53674 -
Journal of the National Cancer Institute Aug 2015
Topics: Antimetabolites, Antineoplastic; Antineoplastic Agents; Enzyme Inhibitors; Female; Humans; Methotrexate; Nitric Oxide; Nitric Oxide Synthase Type II; Triple Negative Breast Neoplasms; omega-N-Methylarginine
PubMed: 26243205
DOI: 10.1093/jnci/djv235 -
Parasites & Vectors Jul 2015Iron plays a pivotal role in the pathogenesis of Trichomonas vaginalis, the causative agent of highly prevalent human trichomoniasis. T. vaginalis resides in the vaginal...
BACKGROUND
Iron plays a pivotal role in the pathogenesis of Trichomonas vaginalis, the causative agent of highly prevalent human trichomoniasis. T. vaginalis resides in the vaginal region, where the iron concentration is constantly changing. Hence, T. vaginalis must adapt to variations in iron availability to establish and maintain an infection. The free radical signaling molecules reactive oxygen species (ROS) and reactive nitrogen species (RNS) have been proven to participate in iron deficiency in eukaryotes. However, little is known about the roles of these molecules in iron-deficient T. vaginalis.
METHODS
T. vaginalis cultured in iron-rich and -deficient conditions were collected for all experiments in this study. Next generation RNA sequencing was conducted to investigate the impact of iron on transcriptome of T. vaginalis. The cell viabilities were monitored after the trophozoites treated with the inhibitors of nitric oxide (NO) synthase (L-NG-monomethyl arginine, L-NMMA) and proteasome (MG132). Hydrogenosomal membrane potential was measured using JC-1 staining.
RESULTS
We demonstrated that NO rather than ROS accumulates in iron-deficient T. vaginalis. The level of NO was blocked by MG132 and L-NMMA, indicating that NO production is through a proteasome and arginine dependent pathway. We found that the inhibition of proteasome activity shortened the survival of iron-deficient cells compared with untreated iron-deficient cells. Surprisingly, the addition of arginine restored both NO level and the survival of proteasome-inhibited cells, suggesting that proteasome-derived NO is crucial for cell survival under iron-limited conditions. Additionally, NO maintains the hydrogenosomal membrane potential, a determinant for cell survival, emphasizing the cytoprotective effect of NO on iron-deficient T. vaginalis. Collectively, we determined that NO produced by the proteasome prolonged the survival of iron-deficient T. vaginalis via maintenance of the hydrogenosomal functions.
CONCLUSION
The findings in this study provide a novel role of NO in adaptation to iron-deficient stress in T. vaginalis and shed light on a potential therapeutic strategy for trichomoniasis.
Topics: Adaptation, Physiological; Animals; Base Sequence; Benzimidazoles; Carbocyanines; Cell Survival; Enzyme Inhibitors; High-Throughput Nucleotide Sequencing; Humans; Iron Deficiencies; Leupeptins; Models, Biological; Nitric Oxide; Nitric Oxide Synthase; Protozoan Proteins; Reactive Oxygen Species; Sequence Analysis, RNA; Transcriptome; Trichomonas Infections; Trichomonas vaginalis; omega-N-Methylarginine
PubMed: 26205151
DOI: 10.1186/s13071-015-1000-5 -
The Journal of Physiology Sep 2015The passive leg movement (PLM) model is a novel approach to assess vascular function. Increasing femoral perfusion pressure (FPP) by moving from the supine to the...
The passive leg movement (PLM) model is a novel approach to assess vascular function. Increasing femoral perfusion pressure (FPP) by moving from the supine to the upright-seated posture augments the vasodilatory response to PLM in the young, with no effect in the old, but whether this augmented vasodilatation is nitric oxide (NO) dependent is unknown. Using an intra-arterial infusion of N(G) -monomethyl-L -arginine (L -NMMA) to inhibit nitric oxide synthase (NOS), the posture-induced increases in the PLM responses in the young were nearly ablated, with no effect of NOS inhibition in the old. Therefore, PLM in combination with alterations in posture can be used to determine changes in NO-mediated vasodilatation with age, and thus, may be a clinically useful tool for assessing NO bioavailability across the human lifespan. We sought to better understand the contribution of nitric oxide (NO) to passive leg movement (PLM)-induced vasodilatation with age, with and without a posture-induced increase in femoral perfusion pressure (FPP). PLM was performed in eight young (24 ± 1 years) and eight old (74 ± 3 years) healthy males, with and without NO synthase inhibition via intra-arterial infusion of N(G) -monomethyl-L -arginine (L -NMMA) into the common femoral artery in both the supine and upright-seated posture. Central and peripheral haemodynamic responses were determined second-by-second with finger photoplethysmography and Doppler ultrasound, respectively. PLM-induced increases in heart rate, stroke volume, cardiac output and reductions in mean arterial pressure were similar between age groups and conditions. In the young, L -NMMA attenuated the peak change in leg vascular conductance (ΔLVCpeak ) in both the supine (control: 7.4 ± 0.9; L -NMMA: 5.2 ± 1.1 ml min(-1) mmHg(-1) , P < 0.05) and upright-seated (control: 12.3 ± 2.0; L -NMMA: 6.4 ± 1.0 ml min(-1) mmHg(-1) , P < 0.05) posture, with no significant change in the old (supine control: 4.2 ± 1.3; supine L -NMMA: 3.4 ± 0.8; upright-seated control: 4.5 ± 0.8; upright-seated L -NMMA: 3.4 ± 0.8 ml min(-1) mmHg(-1) , P > 0.05). Increased FPP augmented the ΔLVCpeak in the young control condition only (P < 0.05). In the upright-seated posture, NOS inhibition attenuated the FPP-induced augmentation of rapid vasodilatation in the young (control: 1.25 ± 0.23; L -NMMA: 0.74 ± 0.11 ml min(-1) mmHg(-1) s(-1) ; P < 0.05), but not the old (control: 0.37 ± 0.07; L -NMMA: 0.25 ± 0.07 ml ml min(-1) mmHg(-1) s(-1) ; P > 0.05). These data reveal that greater FPP increases the role of NO in PLM-induced vasodilatation in the young, but not the old, due to reduced NO bioavailability with age. Therefore, PLM involving alterations in posture may be useful to determine changes in NO bioavailability with age.
Topics: Adolescent; Adult; Aging; Femoral Artery; Hemodynamics; Humans; Leg; Male; Movement; Nitric Oxide; Vasodilation; Young Adult; omega-N-Methylarginine
PubMed: 26108562
DOI: 10.1113/JP270195 -
Cell Death & Disease Jun 2015The sarcoendoplasmic reticulum Ca(2+) ATPase 2b (SERCA2b) pump maintains a steep Ca(2+) concentration gradient between the cytosol and ER lumen in the pancreatic...
The sarcoendoplasmic reticulum Ca(2+) ATPase 2b (SERCA2b) pump maintains a steep Ca(2+) concentration gradient between the cytosol and ER lumen in the pancreatic β-cell, and the integrity of this gradient has a central role in regulated insulin production and secretion, maintenance of ER function and β-cell survival. We have previously demonstrated loss of β-cell SERCA2b expression under diabetic conditions. To define the mechanisms underlying this, INS-1 cells and rat islets were treated with the proinflammatory cytokine interleukin-1β (IL-1β) combined with or without cycloheximide or actinomycin D. IL-1β treatment led to increased inducible nitric oxide synthase (iNOS) gene and protein expression, which occurred concurrently with the activation of AMP-activated protein kinase (AMPK). IL-1β led to decreased SERCA2b mRNA and protein expression, whereas time-course experiments revealed a reduction in protein half-life with no change in mRNA stability. Moreover, SERCA2b protein but not mRNA levels were rescued by treatment with the NOS inhibitor l-NMMA (NG-monomethyl L-arginine), whereas the NO donor SNAP (S-nitroso-N-acetyl-D,L-penicillamine) and the AMPK activator AICAR (5-aminoimidazole-4-carboxamide ribonucleotide) recapitulated the effects of IL-1β on SERCA2b protein stability. Similarly, IL-1β-induced reductions in SERCA2b expression were rescued by pharmacological inhibition of AMPK with compound C or by transduction of a dominant-negative form of AMPK, whereas β-cell death was prevented in parallel. Finally, to determine a functional relationship between NO and AMPK signaling and SERCA2b activity, fura-2/AM (fura-2-acetoxymethylester) Ca(2+) imaging experiments were performed in INS-1 cells. Consistent with observed changes in SERCA2b expression, IL-1β, SNAP and AICAR increased cytosolic Ca(2+) and decreased ER Ca(2+) levels, suggesting congruent modulation of SERCA activity under these conditions. In aggregate, these results show that SERCA2b protein stability is decreased under inflammatory conditions through NO- and AMPK-dependent pathways and provide novel insight into pathways leading to altered β-cell calcium homeostasis and reduced β-cell survival in diabetes.
Topics: AMP-Activated Protein Kinases; Aminoimidazole Carboxamide; Animals; Apoptosis; Calcium; Cycloheximide; Dactinomycin; Diabetes Mellitus; Endoplasmic Reticulum; Enzyme Activation; Fura-2; Humans; Insulin-Secreting Cells; Insulinoma; Interleukin-1beta; Male; Nitric Oxide; Nitric Oxide Synthase Type II; Oxidative Stress; RNA, Messenger; Rats; Rats, Wistar; Ribonucleotides; S-Nitroso-N-Acetylpenicillamine; Sarcoplasmic Reticulum Calcium-Transporting ATPases; Signal Transduction; omega-N-Methylarginine
PubMed: 26086963
DOI: 10.1038/cddis.2015.154