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Hypertension (Dallas, Tex. : 1979) Oct 2014Obesity is an important risk factor for the development of insulin resistance. Initial compensatory mechanisms include an increase in insulin levels, which are thought... (Randomized Controlled Trial)
Randomized Controlled Trial
Obesity is an important risk factor for the development of insulin resistance. Initial compensatory mechanisms include an increase in insulin levels, which are thought to induce sympathetic activation in an attempt to restore energy balance. We have previously shown, however, that sympathetic activity has no beneficial effect on resting energy expenditure in obesity. On the contrary, we hypothesize that sympathetic activation contributes to insulin resistance. To test this hypothesis, we determined insulin sensitivity using a standard hyperinsulinemic euglycemic clamp protocol in obese subjects randomly assigned in a crossover design 1 month apart to receive saline (intact day) or trimetaphan (4 mg/min IV, autonomic blocked day). Whole-body glucose uptake (MBW in mg/kg per minute) was used as index of maximal muscle glucose use. During autonomic blockade, we clamped blood pressure with a concomitant titrated intravenous infusion of the nitric oxide synthase inhibitor N-monomethyl-L-arginine. Of the 21 obese subjects (43±2 years; 35±2 kg/m(2) body mass index) studied, 14 were insulin resistant; they were more obese, had higher plasma glucose and insulin, and had higher muscle sympathetic nerve activity (23.3±1.5 versus 17.2±2.1 burst/min; P=0.03) when compared with insulin-sensitive subjects. Glucose use improved during autonomic blockade in insulin-resistant subjects (MBW 3.8±0.3 blocked versus 3.1±0.3 mg/kg per minute intact; P=0.025), with no effect in the insulin-sensitive group. These findings support the concept that sympathetic activation contributes to insulin resistance in obesity and may result in a feedback loop whereby the compensatory increase in insulin levels contributes to greater sympathetic activation.
Topics: Adult; Autonomic Nervous System; Blood Glucose; Blood Pressure; Cross-Over Studies; Enzyme Inhibitors; Female; Ganglionic Blockers; Glucose Clamp Technique; Humans; Insulin; Insulin Resistance; Male; Middle Aged; Muscles; Nitric Oxide Synthase; Obesity; Trimethaphan; omega-N-Methylarginine
PubMed: 25001269
DOI: 10.1161/HYPERTENSIONAHA.114.03738 -
BMC Nephrology Mar 2017Tolvaptan is a selective vasopressin receptor antagonist. Nitric Oxide (NO) promotes renal water and sodium excretion, but the effect is unknown in the nephron's... (Randomized Controlled Trial)
Randomized Controlled Trial
BACKGROUND
Tolvaptan is a selective vasopressin receptor antagonist. Nitric Oxide (NO) promotes renal water and sodium excretion, but the effect is unknown in the nephron's principal cells. In a dose-response study, we measured the effect of tolvaptan on renal handling of water and sodium and systemic hemodynamics, during baseline and NO-inhibition with L-NMMA (L-NG-monomethyl-arginine).
METHODS
In a randomized, placebo-controlled, double blind, cross over study, 15 healthy subjects received tolvaptan 15, 30 and 45 mg or placebo. L-NMMA was given as a bolus followed by continuous infusion during 60 min. We measured urine output (UO), free water clearance (C), fractional excretion of sodium (FE), urinary aquaporin-2 channels (u-AQP2) and epithelial sodium channels (u-ENaCγ), plasma vasopressin (p-AVP) and central blood pressure (cBP).
RESULTS
During baseline, FE was unchanged. Tolvaptan decreased u-ENaC dose-dependently and increased p-AVP threefold, whereas u-AQP2 was unchanged. During tolvaptan with NO-inhibition, UO and C decreased dose-dependently. FE decreased dose-independently and u-ENaC remained unchanged. Central BP increased equally after all treatments.
CONCLUSIONS
During baseline, fractional excretion of sodium was unchanged. During tolvaptan with NO-inhibition, renal water excretion was reduced dose dependently, and renal sodium excretion was reduced unrelated to the dose, partly via an AVP dependent mechanism. Thus, tolvaptan antagonized the reduction in renal water and sodium excretion during NO-inhibition. Most likely, the lack of decrease in AQP2 excretion by tolvaptan could be attributed to a counteracting effect of the high level of p-AVP.
TRIAL REGISTRATION
Clinical Trial no: NCT02078973 . Registered 1 March 2014.
Topics: Adult; Benzazepines; Blood Pressure; Body Water; Cross-Over Studies; Dose-Response Relationship, Drug; Double-Blind Method; Glomerular Filtration Rate; Humans; Kidney; Nitric Oxide; Placebo Effect; Sodium; Tolvaptan; Water-Electrolyte Balance; omega-N-Methylarginine
PubMed: 28288570
DOI: 10.1186/s12882-017-0501-1 -
Oxidative Medicine and Cellular... 2020() is one of the most important agents of dermatophyte infection in humans. The aim of this experiment was to evaluate the effect of HaCaT cells on , investigate the...
() is one of the most important agents of dermatophyte infection in humans. The aim of this experiment was to evaluate the effect of HaCaT cells on , investigate the responsible mechanism of action, and explore the role of reactive oxygen species (ROS) and nitric oxide (NO) in the inhibition of growth by HaCaT cells. The viability of fungi treated with HaCaT cells alone and with HaCaT cells combined with pretreatment with the NADPH oxidase inhibitor (DPI) or the nitric oxide synthase (NOS) inhibitor L-NMMA was determined by enumerating the colony-forming units. NOS, ROS, and NO levels were quantified using fluorescent probes. The levels of the NOS inhibitor asymmetric dimethylarginine (ADMA) were determined by enzyme-linked immunosorbent assay (ELISA). Micromorphology was observed using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). In addition, fungal keratinase activity was assessed by measuring dye release from keratin azure. In vitro fungal viability, keratinase activity, and ADMA content decreased after HaCaT cell intervention, whereas the levels of ROS, NO, and NOS increased. The micromorphology was abnormal. Fungi pretreated with DPI and L-NMMA exhibited opposite effects. HaCaT cells inhibited the growth and pathogenicity of in vitro. A suggested mechanism is that ROS and NO play an important role in the inhibition of growth by HaCaT cells.
Topics: Arginine; Catecholamines; Cell Line; Enzyme Inhibitors; Humans; Imidazolines; Microscopy, Electron, Scanning; Microscopy, Electron, Transmission; NADPH Oxidases; Nitric Oxide; Nitric Oxide Synthase; Peptide Hydrolases; Reactive Oxygen Species; Trichophyton; omega-N-Methylarginine
PubMed: 32104540
DOI: 10.1155/2020/8548619 -
British Journal of Clinical Pharmacology Oct 2014Clinical trials suggest that statins have beneficial effects on the cardiovascular system independent from their cholesterol lowering properties. In patients with... (Randomized Controlled Trial)
Randomized Controlled Trial
AIMS
Clinical trials suggest that statins have beneficial effects on the cardiovascular system independent from their cholesterol lowering properties. In patients with chronic kidney disease stage II-III, we tested the hypothesis that atorvastatin increased systemic and renal nitric oxide (NO) availability using L-N(G) -monomethyl arginine (L-NMMA) as an inhibitor of NO production.
METHODS
In a randomized, placebo-controlled, crossover study patients were treated with atorvastatin for 5 days with standardized diet and fluid intake. Glomerular filtration reate (GFR), fractional excretions of sodium (FENa ), urinary excretion of aquaporin-2 (u-AQP2) and epithelial sodium channels (u-ENaCγ ), vasoactive hormones (renin, angiotensin II, aldosterone, arginine vasopressin, endothelin-1 and brain natriuretic peptide) and central blood pressure (BP) estimated by applanation tonometry were measured before and after systemic administration of the NO inhibitor L-NMMA.
RESULTS
Atorvastatin caused a significant reduction in U-ENaCγ , but sodium excretion, C H 2 O , FENa and u-AQP2 were not changed by atorvastatin. L-NMMA reduced renal effect variables, including GFR, FENa and u-ENaCγ and increased brachial BP and central BP to a similar extent during both treatments. Vasoactive hormones were changed in the same way by L-NMMA during atorvastatin and placebo treatment.
CONCLUSION
During, atorvastatin and placebo treatment, inhibition of nitric oxide synthesis induced the same response in brachial and central blood pressure, GFR, renal tubular function and vasoactive hormones. Thus, the data do not support that atorvastatin changes nitric oxide availability in patients with mild nephropathy. The reduced u-ENaC may reflect changes in sodium absorption in the nephron induced by atorvastatin.
Topics: Adult; Aged; Aged, 80 and over; Atorvastatin; Blood Pressure; Cross-Over Studies; Double-Blind Method; Epithelial Sodium Channels; Female; Glomerular Filtration Rate; Heptanoic Acids; Humans; Hydroxymethylglutaryl-CoA Reductase Inhibitors; Kidney; Male; Middle Aged; Nitric Oxide; Pyrroles; Renal Insufficiency, Chronic; Vascular Stiffness; omega-N-Methylarginine
PubMed: 24697877
DOI: 10.1111/bcp.12390 -
American Journal of Physiology. Heart... Jun 2015Endothelial cell release of nitric oxide (NO) is a defining characteristic of nondiseased arteries, and abnormal endothelial NO release is both a marker of early...
Endothelial cell release of nitric oxide (NO) is a defining characteristic of nondiseased arteries, and abnormal endothelial NO release is both a marker of early atherosclerosis and a predictor of its progression and future events. Healthy coronaries respond to endothelial-dependent stressors with vasodilatation and increased coronary blood flow (CBF), but those with endothelial dysfunction respond with paradoxical vasoconstriction and reduced CBF. Recently, coronary MRI and isometric handgrip exercise (IHE) were reported to noninvasively quantify coronary endothelial function (CEF). However, it is not known whether the coronary response to IHE is actually mediated by NO and/or whether it is reproducible over weeks. To determine the contribution of NO, we studied the coronary response to IHE before and during infusion of N(G)-monomethyl-l-arginine (l-NMMA, 0.3 mg·kg(-1)·min(-1)), a NO-synthase inhibitor, in healthy volunteers. For reproducibility, we performed two MRI-IHE studies ~8 wk apart in healthy subjects and patients with coronary artery disease (CAD). Changes from rest to IHE in coronary cross-sectional area (%CSA) and diastolic CBF (%CBF) were quantified. l-NMMA completely blocked normal coronary vasodilation during IHE [%CSA, 12.9 ± 2.5 (mean ± SE, placebo) vs. -0.3 ± 1.6% (l-NMMA); P < 0.001] and significantly blunted the increase in flow [%CBF, 47.7 ± 6.4 (placebo) vs. 10.6 ± 4.6% (l-NMMA); P < 0.001]. MRI-IHE measures obtained weeks apart strongly correlated for CSA (P < 0.0001) and CBF (P < 0.01). In conclusion, the normal human coronary vasoactive response to IHE is primarily mediated by NO. This noninvasive, reproducible MRI-IHE exam of NO-mediated CEF promises to be useful for studying CAD pathogenesis in low-risk populations and for evaluating translational strategies designed to alter CAD in patients.
Topics: Adult; Aged; Case-Control Studies; Coronary Artery Disease; Coronary Circulation; Coronary Vessels; Endothelium, Vascular; Enzyme Inhibitors; Exercise; Female; Hand Strength; Heart Function Tests; Humans; Magnetic Resonance Imaging; Male; Middle Aged; Nitric Oxide; Nitric Oxide Synthase Type III; Vasoconstriction; Vasodilation; omega-N-Methylarginine
PubMed: 25820391
DOI: 10.1152/ajpheart.00023.2015 -
Molecules (Basel, Switzerland) May 2020(QM)-a member of the Fagaceae family-has been used as traditional medicine in Korea, China and Mongolia as a treatment for inflammation of oral, genital or anal mucosa...
(QM)-a member of the Fagaceae family-has been used as traditional medicine in Korea, China and Mongolia as a treatment for inflammation of oral, genital or anal mucosa and for external inflammation of skin. To treat acne vulgaris (AV), we evaluated the inhibition of inflammatory cytokines (IL-6 and IL-8) of QM leaf extract (QML) and its main compound, pedunculagin (PD) in vitro and 5α-reductase inhibitory activity by western blotting. As results, QML and PD showed potent NO production inhibitory activity compared with the positive control (PC), NG-monomethyl-L-arginine (L-NMMA). QML and PD was also showed the decreases of IL-6 and IL-8 compared with the PC, EGCG and exhibited potent 5α-reductase type 1 inhibitory activities compared with the PC, dutasteride.
Topics: 5-alpha Reductase Inhibitors; Acne Vulgaris; Anti-Inflammatory Agents; Cell Line; Cholestenone 5 alpha-Reductase; Down-Regulation; Humans; Interleukin-6; Interleukin-8; Lipopolysaccharides; Medicine, Traditional; Nitric Oxide; Plant Extracts; Plant Leaves; Quercus; Tannins; omega-N-Methylarginine
PubMed: 32380665
DOI: 10.3390/molecules25092154 -
PloS One 2014The actin-sequestering protein thymosin beta-4 (Tβ4) is involved in various cellular and physiological processes such as proliferation, motility, growth and metastasis....
The actin-sequestering protein thymosin beta-4 (Tβ4) is involved in various cellular and physiological processes such as proliferation, motility, growth and metastasis. Nitric oxide (NO) promotes tumor invasiveness and metastasis by activating various enzymes. Herein, we investigated whether hypoxia-inducible NO regulates Tβ4 expression and cancer cell migration using HeLa cervical cancer cells. NO production and Tβ4 expression were increased in a hypoxic condition. The treatment with N-(β-D-Glucopyranosyl)-N2-acetyl-S-nitroso-D, L-penicillaminamide (SNAP-1), to generate NO, enhanced the transcription of Tβ4 and cancer cell migration. SNAP-1-induced cell migration was decreased by the inhibition of Tβ4 with small interference (si) RNA. In a hypoxic condition, treatment with N(G)-monomethyl-L-arginine (L-NMMA), nitric oxide synthase (NOS) inhibitor, reduced Tβ4 transcriptional activity, and hypoxia-inducible factor (HIF)-1α. Hypoxia-induced cancer cell migration was also decreased by L-NMMA treatment. In a normoxic condition, Tβ4 transcriptional activity was decreased in the cells incubated in the presence of L-NMMA after co-transfection with Tβ4 promoter and GST-conjugated HIF-1α. Collectively, these results suggest that NO could regulate the expression of Tβ4 by direct or indirect effect of HIF-1α on Tβ4 promoter.
Topics: Actins; Cell Movement; Gene Expression Regulation; HeLa Cells; Humans; Hypoxia; Hypoxia-Inducible Factor 1, alpha Subunit; Nitric Oxide; Nitric Oxide Synthase; Promoter Regions, Genetic; Protein Binding; RNA Interference; RNA, Small Interfering; Thymosin; omega-N-Methylarginine
PubMed: 25271630
DOI: 10.1371/journal.pone.0106532 -
The Journal of Physiology Jun 2015During exercise there is a balance between vasoactive factors that facilitate increases in blood flow and oxygen delivery to the active tissue and the sympathetic...
KEY POINTS
During exercise there is a balance between vasoactive factors that facilitate increases in blood flow and oxygen delivery to the active tissue and the sympathetic nervous system, which acts to limit muscle blood flow for the purpose of blood pressure regulation. Functional sympatholysis describes the ability of contracting skeletal muscle to blunt the stimulus for vasoconstriction, yet the underlying signalling of this response in humans is not well understood. We tested the hypothesis that activation of inwardly rectifying potassium channels and the sodium-potassium ATPase pump, two potential vasodilator pathways within blood vessels, contributes to the ability to blunt α1 -adrenergic vasoconstriction. Our results show preserved blunting of α1 -adrenergic vasconstriction despite blockade of these vasoactive factors. Understanding this complex phenomenon is important as it is impaired in a variety of clinical populations.
ABSTRACT
Sympathetic vasoconstriction in contracting skeletal muscle is blunted relative to that which occurs in resting tissue; however, the mechanisms underlying this 'functional sympatholysis' remain unclear in humans. We tested the hypothesis that α1 -adrenergic vasoconstriction is augmented during exercise following inhibition of inwardly rectifying potassium (KIR ) channels and Na(+) /K(+) -ATPase (BaCl2 + ouabain). In young healthy humans, we measured forearm blood flow (Doppler ultrasound) and calculated forearm vascular conductance (FVC) at rest, during steady-state stimulus conditions (pre-phenylephrine), and after 2 min of phenylephrine (PE; an α1 -adrenoceptor agonist) infusion via brachial artery catheter in response to two different stimuli: moderate (15% maximal voluntary contraction) rhythmic handgrip exercise or adenosine infusion. In Protocol 1 (n = 11 subjects) a total of six trials were performed in three conditions: control (saline), combined enzymatic inhibition of nitric oxide (NO) and prostaglandin (PG) synthesis (l-NMMA + ketorolac) and combined inhibition of NO, PGs, KIR channels and Na(+) /K(+) -ATPase (l-NMMA + ketorolac + BaCl2 + ouabain). In Protocol 2 (n = 6) a total of four trials were performed in two conditions: control (saline), and combined KIR channel and Na(+) /K(+) -ATPase inhibition. All trials occurred after local β-adrenoceptor blockade (propranolol). PE-mediated vasoconstriction was calculated (%ΔFVC) in each condition. Contrary to our hypothesis, despite attenuated exercise hyperaemia of ∼30%, inhibition of KIR channels and Na(+) /K(+) -ATPase, combined with inhibition of NO and PGs (Protocol 1) or alone (Protocol 2) did not enhance α1 -mediated vasoconstriction during exercise (Protocol 1: -27 ± 3%; P = 0.2 vs. control, P = 0.4 vs. l-NMMA + ketorolac; Protocol 2: -21 ± 7%; P = 0.9 vs. control). Thus, contracting human skeletal muscle maintains the ability to blunt α1 -adrenergic vasoconstriction during combined KIR channel and Na(+) /K(+) -ATPase inhibition.
Topics: Adenosine; Adult; Barium Compounds; Brachial Artery; Chlorides; Exercise; Female; Forearm; Hand Strength; Humans; Ketorolac; Male; Muscle Contraction; Muscle, Skeletal; Ouabain; Potassium Channels, Inwardly Rectifying; Propranolol; Receptors, Adrenergic, alpha-1; Regional Blood Flow; Sodium-Potassium-Exchanging ATPase; Vasoconstriction; Young Adult; omega-N-Methylarginine
PubMed: 25893955
DOI: 10.1113/JP270461 -
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 -
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