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Journal of Applied Physiology... Feb 2018Nitric oxide (NO)-mediated vasodilation contributes to the rapid rise in muscle blood flow at exercise onset. This occurs via increased cyclic guanosine monophosphate...
Nitric oxide (NO)-mediated vasodilation contributes to the rapid rise in muscle blood flow at exercise onset. This occurs via increased cyclic guanosine monophosphate (cGMP), which is catabolized by phosphodiesterase-5 (PDE-5). Whether PDE-5 limits exercise vasodilation onset kinetics is unknown. We hypothesized the time course of exercise vasodilation would be 1) accelerated during PDE-5 inhibition (sildenafil citrate, SDF) and 2) decelerated during NO synthase inhibition ( N-monomethyl-l-arginine, l-NMMA), and 3) the effect of SDF on vasodilation onset kinetics would be attenuated with concurrent l-NMMA. Data from 29 healthy adults were analyzed. Individuals completed 5 min of moderate-intensity forearm exercise under control conditions and during 1) oral SDF ( n = 8), 2) intra-arterial l-NMMA ( n = 15), or 3) combined SDF + l-NMMA ( n = 6). Forearm blood flow (FBF; Doppler ultrasound of the brachial artery) and mean brachial artery blood pressure (MAP) were measured continuously. Forearm vascular conductance (FVC, FBF ÷ MAP) was curve-fit with a monoexponential model, and vasodilation onset kinetics were assessed by mean response time (MRT, time to achieve 63% of steady state). SDF had no effect on MRT ( P = 0.90). NOS inhibition increased MRT ( P = 0.01). MRT during SDF+l-NMMA was not different from control exercise ( P = 0.76). PDE-5 inhibition alone has no effect on rapid-onset vasodilation. Whereas NOS inhibition decelerates vasodilator kinetics, when combined with SDF, vasodilator kinetics do not differ from control. These data suggest NO-independent activation of cGMP occurs at exercise onset; thus PDE-5 inhibition may improve vasodilation in pathologies where NO bioavailability is impaired. NEW & NOTEWORTHY We show that when NO bioavailability is reduced, PDE-5 inhibition can restore vasodilation onset kinetics of exercise-mediated vasodilation via NO-independent cGMP pathways. These data suggest PDE-5 inhibition may improve exercise vasodilation onset kinetics in pathologies where NO bioavailability is impaired.
Topics: Adult; Cyclic GMP; Exercise; Female; Humans; Male; Nitric Oxide Synthase; Phosphodiesterase 5 Inhibitors; Sildenafil Citrate; Vasodilation; Young Adult; omega-N-Methylarginine
PubMed: 28982942
DOI: 10.1152/japplphysiol.00483.2017 -
Journal of Applied Physiology... Dec 2017Broxterman RM, Trinity JD, Gifford JR, Kwon OS, Kithas AC, Hydren JR, Nelson AD, Morgan DE, Jessop JE, Bledsoe AD, Richardson RS. Single passive leg movement assessment...
Broxterman RM, Trinity JD, Gifford JR, Kwon OS, Kithas AC, Hydren JR, Nelson AD, Morgan DE, Jessop JE, Bledsoe AD, Richardson RS. Single passive leg movement assessment of vascular function: contribution of nitric oxide. J Appl Physiol 123: 1468-1476, 2017. First published August 31, 2017; doi:10.1152/japplphysiol.00533.2017.-The assessment of passive leg movement (PLM)-induced leg blood flow (LBF) and vascular conductance (LVC) is a novel approach to assess vascular function that has recently been simplified to only a single PLM (sPLM), thereby increasing the clinical utility of this technique. As the physiological mechanisms mediating the robust increase in LBF and LVC with sPLM are unknown, we tested the hypothesis that nitric oxide (NO) is a major contributor to the sPLM-induced LBF and LVC response. In nine healthy men, sPLM was performed with and without NO synthase inhibition by intra-arterial infusion of N-monomethyl-l-arginine (l-NMMA). Doppler ultrasound and femoral arterial pressure were used to determine LBF and LVC, which were characterized by the peak change (ΔLBF and ΔLVC) and area under the curve (LBF and LVC). l-NMMA significantly attenuated ΔLBF [492 ± 153 (l-NMMA) vs. 719 ± 238 (control) ml/min], LBF [57 ± 34 (l NMMA) vs. 147 ± 63 (control) ml], ΔLVC [4.7 ± 1.1 (l-NMMA) vs. 8.0 ± 3.0 (control) ml·min·mmHg], and LVC [0.5 ± 0.3 (l-NMMA) vs. 1.6 ± 0.9 (control) ml/mmHg]. The magnitude of the NO contribution to LBF and LVC was significantly correlated with the magnitude of the control responses ( r = 0.94 for ΔLBF, r = 0.85 for LBF, r = 0.94 for ΔLVC, and r = 0.95 for LVC). These data establish that the sPLM-induced hyperemic and vasodilatory response is predominantly (~65%) NO-mediated. As such, sPLM appears to be a promising, simple, in vivo assessment of NO-mediated vascular function and NO bioavailability. NEW & NOTEWORTHY Passive leg movement (PLM), a novel assessment of vascular function, has been simplified to a single PLM (sPLM), thereby increasing the clinical utility of this technique. However, the role of nitric oxide (NO) in mediating the robust sPLM hemodynamic responses is unknown. This study revealed that sPLM induces a hyperemic and vasodilatory response that is predominantly NO-mediated and, as such, appears to be a promising simple, in vivo, clinical assessment of NO-mediated vascular function and, therefore, NO bioavailability.
Topics: Adult; Arterial Pressure; Enzyme Inhibitors; Hemodynamics; Humans; Hyperemia; Leg; Male; Movement; Nitric Oxide; Regional Blood Flow; Vasodilation; Young Adult; omega-N-Methylarginine
PubMed: 28860173
DOI: 10.1152/japplphysiol.00533.2017 -
Journal of Cerebral Blood Flow and... Feb 2019Our goal was to examine whether in utero exposure to alcohol impaired reactivity of cerebral arterioles during development. We fed Sprague-Dawley dams a liquid diet with...
Our goal was to examine whether in utero exposure to alcohol impaired reactivity of cerebral arterioles during development. We fed Sprague-Dawley dams a liquid diet with or without alcohol (3% ethanol) for the duration of pregnancy (21-23 days). Around 4-6 weeks after birth, we examined reactivity of cerebral arterioles to eNOS- (ADP) and nNOS-dependent (NMDA) agonists in the offspring. We found that in utero exposure to alcohol attenuated responses of cerebral arterioles to ADP and NMDA, but not to nitroglycerin in rats exposed to alcohol in utero. L-NMMA reduced responses to agonists in control rats, but not in rats exposed to alcohol in utero. Treatment of dams with apocynin for the duration of pregnancy rescued the impairment in reactivity to ADP and NMDA in the offspring. Protein expression of NOX-2 and NOX-4 was increased in alcohol rats compared to control rats. We also found an increase in superoxide levels in the cortex of rats exposed to alcohol in utero. Our findings suggest that in utero exposure to alcohol impairs eNOS and nNOS reactivity of cerebral arterioles via a chronic increase in oxidative stress.
Topics: Acetophenones; Adenosine Diphosphate; Animals; Arterioles; Cerebral Cortex; Chronic Disease; Ethanol; Female; Male; Maternal Exposure; NADPH Oxidase 2; NADPH Oxidase 4; Nitric Oxide Synthase Type I; Nitric Oxide Synthase Type III; Oxidative Stress; Pregnancy; Prenatal Exposure Delayed Effects; Rats; Rats, Sprague-Dawley; Superoxides; omega-N-Methylarginine
PubMed: 28840777
DOI: 10.1177/0271678X17728163 -
PloS One 2017Nitric oxide synthase (NOS) is a biomarker/target in sepsis. NOS activity is driven by amino acids, which cycle to regulate the substrate L-arginine in parallel with...
RATIONALE
Nitric oxide synthase (NOS) is a biomarker/target in sepsis. NOS activity is driven by amino acids, which cycle to regulate the substrate L-arginine in parallel with cycles which regulate the endogenous inhibitors ADMA and L-NMMA. The relationship between amines and the consequence of plasma changes on iNOS activity in early sepsis is not known.
OBJECTIVE
Our objective was to apply a metabolomics approach to determine the influence of sepsis on a full array of amines and what consequence these changes may have on predicted iNOS activity.
METHODS AND MEASUREMENTS
34 amino acids were measured using ultra purification mass spectrometry in the plasma of septic patients (n = 38) taken at the time of diagnosis and 24-72 hours post diagnosis and of healthy volunteers (n = 21). L-arginine and methylarginines were measured using liquid-chromatography mass spectrometry and ELISA. A top down approach was also taken to examine the most changed metabolic pathways by Ingenuity Pathway Analysis. The iNOS supporting capacity of plasma was determined using a mouse macrophage cell-based bioassay.
MAIN RESULTS
Of all the amines measured 22, including L-arginine and ADMA, displayed significant differences in samples from patients with sepsis. The functional consequence of increased ADMA and decreased L-arginine in context of all cumulative metabolic changes in plasma resulted in reduced iNOS supporting activity associated with sepsis.
CONCLUSIONS
In early sepsis profound changes in amine levels were defined by dominant changes in the iNOS canonical pathway resulting in functionally meaningful changes in the ability of plasma to regulate iNOS activity ex vivo.
Topics: Adult; Aged; Amines; Animals; Arginine; Cell Line; Chromatography, Liquid; Enzyme-Linked Immunosorbent Assay; Female; Humans; Male; Mass Spectrometry; Metabolomics; Mice; Middle Aged; Nitric Oxide Synthase; Nitric Oxide Synthase Type II; Sepsis; omega-N-Methylarginine
PubMed: 28813479
DOI: 10.1371/journal.pone.0183025 -
Graefe's Archive For Clinical and... Oct 2017Occlusion of retinal vessels leads to retinal ischaemia and hypoxia, which induces vasodilatation in adjacent retinal areas in order to normalize retinal oxygenation.... (Clinical Trial)
Clinical Trial
Occlusion of retinal vessels leads to retinal ischaemia and hypoxia, which induces vasodilatation in adjacent retinal areas in order to normalize retinal oxygenation. Previous studies have shown that NO and COX products are involved in hypoxia-induced dilatation of retinal arterioles in vitro and in vivo, and that this response is disturbed in patients with diabetes mellitus. However, it is unknown to what extent post-hypoxic recovery of the diameter of retinal arterioles depends on NO and COX products in normal persons and in diabetic patients. The Dynamic Vessel Analyzer (DVA) was used to study the post-hypoxic diameter changes of larger retinal vessels in 20 normal persons, 20 diabetic patients without diabetic retinopathy, and in 18 patients with diabetic maculopathy before and after inhibition of the synthesis of nitric oxide and COX products. In normal persons, the arterioles had re-constricted (p > 0.99) 2 minutes after termination of hypoxia in the absence of antagonists, but not after treatment with L-NMMA and diclofenac (p < 0.01 for all comparisons). In diabetic patients without retinopathy, the arterioles showed no diameter changes after termination of hypoxia during any of the interventions. In patients with diabetic maculopathy hypoxia had not dilated retinal arterioles (p > 0.1 for all comparisons) to allow the study of re-constriction. In all groups, the dilatation of venules remained significantly increased during the post-hypoxic observation period, both in the absence and in the presence of L-NMMA and diclofenac.Post-hypoxic constriction of retinal arterioles depends on NO and COX products, and is impaired in diabetic patients before the development of retinopathy. This disturbance may contribute to the development of diabetic retinopathy, and should be the target of future interventional studies aimed at preventing and treating the disease.ClinicalTrials.gov identifier: NCT01689090.
Topics: Adult; Arterioles; Cyclooxygenase Inhibitors; Diabetic Retinopathy; Diclofenac; Drug Therapy, Combination; Enzyme Inhibitors; Female; Humans; Hypoxia; Male; Middle Aged; Nitric Oxide; Retinal Vessels; Vasoconstriction; Young Adult; omega-N-Methylarginine
PubMed: 28752370
DOI: 10.1007/s00417-017-3746-2 -
Immunology Letters Oct 2017Macrophages are remarkably versatile in their ability to recognize and respond to a wide range of stimuli by expressing a variety of surface and intracellular receptors...
Macrophages are remarkably versatile in their ability to recognize and respond to a wide range of stimuli by expressing a variety of surface and intracellular receptors and triggering multiple signal transduction pathways. The onset of microbial infection is primarily determined by the initial contacts made by the microbes with the host macrophages. Although there prevail a relationship between the chemokine receptor and Toll like receptors during disease, particularly TLR-2 and CCR-2 signaling interdependence on each other has not been yet investigated during acute staphylococcal infection. Thus, the present study was aimed to trace possible interaction between CCR-2 and TLR-2 in peritoneal macrophages during acute Staphylococcus aureus infection. We found that neutralization of CCR-2 attenuates TLR-2 expression and restricts S. aureus burden but TLR-2 neutralization augments CCR-2 expression in macrophages, along with compromised host-derived reactive oxygen species production. S. aureus infection to CCR-2 intact but TLR-2 neutralized macrophages triggered production of IL-1β, TNF-α, IL-6, IFN-γ, MCP-1 and expression of iNOS, TNFR-1 and GPx with concomitant decrease in IL-10 production. Further, study with NG-monomethyl-l-arginine (L-NMMA) [iNOS blocker] and buthionine sulfoximine (BSO) [GPx blocker] revealed that S. aureus infection enhanced TLR-2 expression in CCR-2 intact and TLR-2 neutralized macrophages possibly via iNOS and TNFR-1 up regulation and GPx down regulation. Overall, our data indicate that targeting CCR-2 with neutralizing antibody in the early phase of S. aureus infection could restrict excessive inflammation with less compromised bacterial killing. It certainly would be a therapeutic strategy in S. aureus induced inflammatory and infective diseases.
Topics: Animals; Antibodies, Neutralizing; Bacteriolysis; Buthionine Sulfoximine; Cells, Cultured; Cytokines; Host-Pathogen Interactions; Macrophages, Peritoneal; Mice; Nitric Oxide Synthase Type II; Reactive Oxygen Species; Receptors, CCR2; Receptors, Tumor Necrosis Factor, Type I; Signal Transduction; Staphylococcal Infections; Staphylococcus aureus; Toll-Like Receptor 2; omega-N-Methylarginine
PubMed: 28736159
DOI: 10.1016/j.imlet.2017.07.011 -
Cellular and Molecular Biology... May 2017Polymorphonuclear granulocytes (PMN) are activated in inflammatory reactions. Intestinal epithelial cells are relevant for maintaining the intestinal barrier. We...
Polymorphonuclear granulocytes (PMN) are activated in inflammatory reactions. Intestinal epithelial cells are relevant for maintaining the intestinal barrier. We examined interactions of PMN and intestinal epithelial cell-like CaCo-2 cells to elucidate their regulation of inflammatory signalling and the impact of cyclooxygenase (COX), nitric oxide (NO) and platelet-activating factor (PAF). Human PMN and CaCo-2 cells, separately and in co-incubation, were stimulated with the calcium ionophore A23187 or with N-Formyl-methionyl-leucyl-phenylalanin (fMLP) that activates PMN only. Human neutrophil elastase (HNE) and respiratory Burst were measured. To evaluate the modulation of inflammatory crosstalk we applied inhibitors of COX (acetyl salicylic acid; ASA), NO-synthase (N-monomethyl-L-arginin; L-NMMA), and the PAF-receptor (WEB2086). Unstimulated, co-incubation of CaCo-2 cells and PMN led to significantly reduced Burst and elevated HNE as compared to PMN. After stimulation with A23187, co-incubation resulted in an inhibition of Burst and HNE. Using fMLP co-incubation failed to modulate Burst but increased HNE. Without stimulation, all three inhibitors abolished the effect of co-incubation on Burst but did not change HNE. ASA partly prevented modulation of Burst L-NMMA and WEB2086 did not change Burst but abolished mitigation of HNE. Without stimulation, co-incubation reduced Burst and elevated HNE. Activation of PMN and CaCo-2 cells by fMLP as compared to A23187 resulted in a completely different pattern of Burst and HNE, possibly due to single vs. dual cell activation. Anti-inflammatory effect of co-incubation might in part be due to due to COX-signalling governing Burst whereas NO- and PAF-dependent signalling seemed to control HNE release.
Topics: Aspirin; Azepines; Caco-2 Cells; Calcimycin; Humans; Inflammation; N-Formylmethionine Leucyl-Phenylalanine; Neutrophils; Pancreatic Elastase; Respiratory Burst; Triazoles; omega-N-Methylarginine
PubMed: 28719356
DOI: 10.14715/cmb/2017.63.5.22 -
Nitric oxide synthase inhibition restores orthostatic tolerance in young vasovagal syncope patients.Heart (British Cardiac Society) Nov 2017Syncope is sudden transient loss of consciousness and postural tone with spontaneous recovery; the most common form is vasovagal syncope (VVS). We previously...
OBJECTIVE
Syncope is sudden transient loss of consciousness and postural tone with spontaneous recovery; the most common form is vasovagal syncope (VVS). We previously demonstrated impaired post-synaptic adrenergic responsiveness in young VVS patients was reversed by blocking nitric oxide synthase (NOS). We hypothesised that nitric oxide may account for reduced orthostatic tolerance in young recurrent VVS patients.
METHODS
We recorded haemodynamics in supine VVS and healthy volunteers (aged 15-27 years), challenged with graded lower body negative pressure (LBNP) (-15, -30, -45 mm Hg each for 5 min, then -60 mm Hg for a maximum of 50 min) with and without NOS inhibitor N-monomethyl-L-arginine acetate (L-NMMA). Saline plus phenylephrine (Saline+PE) was used as volume and pressor control for L-NMMA.
RESULTS
Controls endured 25.9±4.0 min of LBNP during Saline+PE compared with 11.6±1.4 min for fainters (p<0.001). After L-NMMA, control subjects endured 24.8±3.2 min compared with 22.6±1.6 min for fainters. Mean arterial pressure decreased more in VVS patients during LBNP with Saline+PE (p<0.001) which was reversed by L-NMMA; cardiac output decreased similarly in controls and VVS patients and was unaffected by L-NMMA. Total peripheral resistance increased for controls but decreased for VVS during Saline+PE (p<0.001) but was similar following L-NMMA. Splanchnic vascular resistance increased during LBNP in controls, but decreased in VVS patients following Saline+PE which L-NMMA restored.
CONCLUSIONS
We conclude that arterial vasoconstriction is impaired in young VVS patients, which is corrected by NOS inhibition. The data suggest that both pre- and post-synaptic arterial vasoconstriction may be affected by nitric oxide.
Topics: Administration, Intravenous; Adolescent; Adult; Age Factors; Arterial Pressure; Arteries; Cardiac Output; Enzyme Inhibitors; Female; Hemodynamics; Humans; Lower Body Negative Pressure; Male; Nitric Oxide Synthase; Syncope, Vasovagal; Time Factors; Treatment Outcome; Vascular Resistance; Vasoconstriction; Young Adult; omega-N-Methylarginine
PubMed: 28501796
DOI: 10.1136/heartjnl-2017-311161 -
High Altitude Medicine & Biology Sep 2017Lüneburg, Nicole, Patricia Siques, Julio Brito, Juan José De La Cruz, Fabiola León-Velarde, Juliane Hannemann, Cristian Ibanez, and Rainer Böger. Long-term...
Lüneburg, Nicole, Patricia Siques, Julio Brito, Juan José De La Cruz, Fabiola León-Velarde, Juliane Hannemann, Cristian Ibanez, and Rainer Böger. Long-term intermittent exposure to high altitude elevates asymmetric dimethylarginine in first exposed young adults. High Alt Med Biol. 18:226-233, 2017.-Hypoxia-induced dysregulation of pulmonary and cerebral circulation may be related to an impaired nitric oxide (NO) pathway. We investigated the effect of chronic intermittent hypobaric hypoxia (CIH) on metabolites of the NO pathway. We measured asymmetric and symmetric dimethylarginine (ADMA and SDMA) and monomethyl-L-arginine (L-NMMA) and assessed their associations with acclimatization in male draftees (n = 72) undergoing CIH shifts at altitude (3550 m) during 3 months. Sixteen Andean natives living at altitude (3675 m) (chronic hypobaric hypoxia [CH]) were included for comparison. In CIH, ADMA and L-NMMA plasma concentrations increased from 1.14 ± 0.04 to 1.95 ± 0.09 μmol/L (mean ± SE) and from 0.22 ± 0.07 to 0.39 ± 0.03 μmol/L, respectively, (p < 0.001 for both) after 3 months, whereas SDMA did not change. The concentrations of ADMA and L-NMMA were higher in CH (3.48 ± 0.07, 0.53 ± 0.08 μmol/L; p < 0.001) as compared with CIH. In both CIH and CH, ADMA correlated with hematocrit (r = 0.07, p < 0.05; r = 0.26; p < 0.01). In CIH, an association of ADMA levels with poor acclimatization status was observed. We conclude that the endogenous NO synthase inhibitors, ADMA and L-NMMA, are elevated in hypoxia. This may contribute to impaired NO production at altitude and may also be predictive of altitude-associated health impairment.
Topics: Acclimatization; Adolescent; Altitude; Altitude Sickness; Arginine; Chile; Humans; Hypoxia; Male; Military Personnel; Occupational Diseases; Young Adult; omega-N-Methylarginine
PubMed: 28453332
DOI: 10.1089/ham.2016.0123 -
European Journal of Applied Physiology Jun 2017Animal studies suggest that the inhibition of nitric oxide synthase (NOS) affects blood flow differently in different skeletal muscles according to their muscle fibre...
PURPOSE
Animal studies suggest that the inhibition of nitric oxide synthase (NOS) affects blood flow differently in different skeletal muscles according to their muscle fibre type composition (oxidative vs glycolytic). Quadriceps femoris (QF) muscle consists of four different muscle parts: vastus intermedius (VI), rectus femoris (RF), vastus medialis (VM), and vastus lateralis (VL) of which VI is located deep within the muscle group and is generally regarded to consist mostly of oxidative muscle fibres.
METHODS
We studied the effect of NOS inhibition on blood flow in these four different muscles by positron emission tomography in eight young healthy men at rest and during one-leg dynamic exercise, with and without combined blockade with prostaglandins.
RESULTS
At rest blood flow in the VI (2.6 ± 1.1 ml/100 g/min) was significantly higher than in VL (1.9 ± 0.6 ml/100 g/min, p = 0.015) and RF (1.7 ± 0.6 ml/100 g/min, p = 0.0015), but comparable to VM (2.4 ± 1.1 ml/100 g/min). NOS inhibition alone or with prostaglandins reduced blood flow by almost 50% (p < 0.001), but decrements were similar in all four muscles (drug × muscle interaction, p = 0.43). During exercise blood flow was also the highest in VI (45.4 ± 5.5 ml/100 g/min) and higher compared to VL (35.0 ± 5.5 ml/100 g/min), RF (38.4 ± 7.4 ml/100 g/min), and VM (36.2 ± 6.8 ml/100 g/min). NOS inhibition alone did not reduce exercise hyperemia (p = 0.51), but combined NOS and prostaglandin inhibition reduced blood flow during exercise (p = 0.002), similarly in all muscles (drug × muscle interaction, p = 0.99).
CONCLUSION
NOS inhibition, with or without prostaglandins inhibition, affects blood flow similarly in different human QF muscles both at rest and during low-to-moderate intensity exercise.
Topics: Adult; Enzyme Inhibitors; Exercise; Humans; Male; Muscle, Skeletal; Nitric Oxide Synthase; Prostaglandin Antagonists; Regional Blood Flow; omega-N-Methylarginine
PubMed: 28432421
DOI: 10.1007/s00421-017-3604-2