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Nutrients Jun 2023Changes in serum concentration of methylarginines and amino acids after exercise are well documented, whereas the effects of exercise applied together with fasting are...
Changes in serum concentration of methylarginines and amino acids after exercise are well documented, whereas the effects of exercise applied together with fasting are still debated and not thoroughly studied. Thus, we hypothesised that alterations in methylarginines such as ADMA, SDMA and L-NMMA might be responsible for decreased exercise performance after 8 days of fasting. Additionally, we propose that conditions in which the human body is exposed to prolonged fasting for more than a week elicit a distinctly different response to exercise than after overnight fasting. A group of 10 healthy men with previous fasting experience participated in the study. The exercise test was performed until exhaustion with a gradually increasing intensity before and after the 8-day fast. Blood samples were collected before and immediately after exercise. ADMA, SDMA, L-NMMA, dimethylamine and amino acids were analysed in serum samples by ID-LC-MS/MS. SDMA, L-NMMA and dimethylamine significantly decreased after 8 days of fasting, whereas ADMA did not change. BCAA, Phe, alanine and some other amino acids increased after fasting. Exercise-induced changes in amino acids were distinct after an 8-day fast compared to overnight fasting. A decrease in physical performance accompanied all of these alterations. In conclusion, our data indicate that neither methyl-arginine changes nor the Trp/BCAA ratio can explain exercise-induced fatigue after fasting. However, the observed decrease in hArg concentration suggests the limited synthesis of creatine, possibly contributing to reduced physical performance.
Topics: Male; Humans; Amino Acids; omega-N-Methylarginine; Chromatography, Liquid; Tandem Mass Spectrometry; Arginine
PubMed: 37447307
DOI: 10.3390/nu15132981 -
Atherosclerosis Nov 2023To understand pathophysiological mechanisms underlying migraine as a cardiovascular risk factor, we studied neuropeptide action and endothelial function as measures of...
BACKGROUND AND AIMS
To understand pathophysiological mechanisms underlying migraine as a cardiovascular risk factor, we studied neuropeptide action and endothelial function as measures of peripheral microvascular function in middle-aged women with or without migraine.
METHODS
We included women with the endocrine disorder polycystic ovary syndrome (PCOS), a population with supposed elevated cardiovascular risk, with and without comorbid migraine. In 26 women without and 23 women with migraine in the interictal phase (mean age 50.8 ± 2.9 years) local thermal hyperemia (LTH) of the skin of the volar forearm was measured cross-sectionally under control conditions, after inhibition of neuropeptide release by 5% lidocaine/prilocaine (EMLA) cream application, and after inhibition of nitric oxide formation by iontophoresis of NG-monomethyl-l-arginine (L-NMMA). Hereafter, changes in the natural logarithm of the reactive hyperemia index (lnRHI) and augmentation index (AI) during reperfusion after occlusion-derived ischemia were measured.
RESULTS
While mean values under control conditions and L-NMMA conditions were similar, migraine patients had a significantly higher mean area of the curve (AUC) of the total LTH response after EMLA application than those without (86.7 ± 26.5% versus 67.9 ± 24.2%; p = 0.014). This was also reflected by a higher median AUC of the plateau phase under similar conditions in women with migraine compared to those without (83.2% (IQR[73.2-109.5]) versus 73.2% (IQR[54.3-92.0]); p = 0.039). Mean changes in lnRHI and AI scores were similar in both groups.
CONCLUSIONS
In PCOS patients with migraine, neuropeptide action was lower compared with those without migraine. While larger studies are warranted, these findings provide a potential mechanism supporting previous findings that migraine may be independent from traditional risk factors, including atherosclerosis.
Topics: Middle Aged; Humans; Female; omega-N-Methylarginine; Polycystic Ovary Syndrome; Vasodilation; Risk Factors; Migraine Disorders
PubMed: 37400308
DOI: 10.1016/j.atherosclerosis.2023.06.078 -
Tumour Virus Research Jun 2023Kaposi's Sarcoma (KS) is a heterogenous, multifocal vascular malignancy caused by the human herpesvirus 8 (HHV8), also known as Kaposi's Sarcoma-Associated Herpesvirus...
Kaposi's Sarcoma (KS) is a heterogenous, multifocal vascular malignancy caused by the human herpesvirus 8 (HHV8), also known as Kaposi's Sarcoma-Associated Herpesvirus (KSHV). Here, we show that KS lesions express iNOS/NOS2 broadly throughout KS lesions, with enrichment in LANA positive spindle cells. The iNOS byproduct 3-nitrotyrosine is also enriched in LANA positive tumor cells and colocalizes with a fraction of LANA-nuclear bodies. We show that iNOS is highly expressed in the L1T3/mSLK tumor model of KS. iNOS expression correlated with KSHV lytic cycle gene expression, which was elevated in late-stage tumors (>4 weeks) but to a lesser degree in early stage (1 week) xenografts. Further, we show that L1T3/mSLK tumor growth is sensitive to an inhibitor of nitric oxide, L-NMMA. L-NMMA treatment reduced KSHV gene expression and perturbed cellular gene pathways relating to oxidative phosphorylation and mitochondrial dysfunction. These finding suggest that iNOS is expressed in KSHV infected endothelial-transformed tumor cells in KS, that iNOS expression depends on tumor microenvironment stress conditions, and that iNOS enzymatic activity contributes to KS tumor growth.
Topics: Animals; Humans; Mice; Antigens, Viral; Herpesvirus 8, Human; omega-N-Methylarginine; Sarcoma, Kaposi; Tumor Microenvironment
PubMed: 36863485
DOI: 10.1016/j.tvr.2023.200259 -
Biochemia Medica Feb 2023This study determines and compares the concentrations of arginine and methylated arginine products ((asymmetric dimethylarginine (ADMA), symmetric dimethylarginine...
INTRODUCTION
This study determines and compares the concentrations of arginine and methylated arginine products ((asymmetric dimethylarginine (ADMA), symmetric dimethylarginine (SDMA), n-monomethyl-1-arginine (L-NMMA) and homoarginine (HA)) for assessment of their association with disease severity in serum samples of COVID-19 patients.
MATERIALS AND METHODS
Serum arginine and methylated arginine products of 57 mild-moderate and 29 severe (N = 86) COVID-19 patients and 21 controls were determined by tandem mass spectrometry. Moreover, the concentrations of some of the routine clinical laboratory parameters -neutrophil lymphocyte ratio (NLR), C-reactive protein, ferritin, D-dimer, and fibrinogen measured during COVID-19 follow-up were also taken into consideration and compared with the concentrations of arginine and methylated arginine products.
RESULTS
Serum ADMA, SDMA and L-NMMA were found to be significantly higher in severe COVID-19 patients, than in both mild-moderate patients and the control group (P < 0.001 for each). In addition, multiple logistic regression analysis indicated L-NMMA (cut-off =120 nmol/L OR = 34, 95% confidence interval (CI) = 3.5-302.0, P= 0.002), CRP (cut-off = 32 mg/L, OR = 37, 95% CI = 4.8-287.0, P < 0.001), and NLR (cut-off = 7, OR = 22, 95% CI = 1.4-335.0, P = 0.020) as independent risk factors for identification of severe patients.
CONCLUSIONS
The concentration of methylated arginine metabolites are significantly altered in COVID-19 disease. The results of this study indicate a significant correlation between the severity of COVID-19 disease and concentrations of CRP, NLR and L-NMMA.
Topics: Humans; Arginine; COVID-19; Disease Progression; omega-N-Methylarginine
PubMed: 36627978
DOI: 10.11613/BM.2023.010701 -
World Journal of Gastroenterology Aug 2022The mechanisms underlying gastrointestinal (GI) dysmotility with ulcerative colitis (UC) have not been fully elucidated. The enteric nervous system (ENS) plays an...
BACKGROUND
The mechanisms underlying gastrointestinal (GI) dysmotility with ulcerative colitis (UC) have not been fully elucidated. The enteric nervous system (ENS) plays an essential role in the GI motility. As a vital neurotransmitter in the ENS, the gas neurotransmitter nitric oxide (NO) may impact the colonic motility. In this study, dextran sulfate sodium (DSS)-induced UC rat model was used for investigating the effects of NO by examining the effects of rate-limiting enzyme nitric oxide synthase (NOS) changes on the colonic motility as well as the role of the ENS in the colonic motility during UC.
AIM
To reveal the relationship between the effects of NOS expression changes in NOS-containing nitrergic neurons and the colonic motility in a rat UC model.
METHODS
Male rats ( = 8/each group) were randomly divided into a control (CG), a UC group (EG1), a UC + thrombin derived polypeptide 508 trifluoroacetic acid (TP508TFA; an NOS agonist) group (EG2), and a UC + NG-monomethyl-L-arginine monoacetate (L-NMMA; an NOS inhibitor) group (EG3). UC was induced by administering 5.5% DSS in drinking water without any other treatment (EG1), while the EG2 and EG3 were gavaged with TP508 TFA and L-NMMA, respectively. The disease activity index (DAI) and histological assessment were recorded for each group, whereas the changes in the proportion of colonic nitrergic neurons were counted using immunofluorescence histochemical staining, Western blot, and enzyme linked immunosorbent assay, respectively. In addition, the contractile tension changes in the circular and longitudinal muscles of the rat colon were investigated using an organ bath system.
RESULTS
The proportion of NOS-positive neurons within the colonic myenteric plexus (MP), the relative expression of NOS, and the NOS concentration in serum and colonic tissues were significantly elevated in EG1, EG2, and EG3 compared with CG rats. In UC rats, stimulation with agonists and inhibitors led to variable degrees of increase or decrease for each indicator in the EG2 and EG3. When the rats in EGs developed UC, the mean contraction tension of the colonic smooth muscle detected was higher in the EG1, EG2, and EG3 than in the CG group. Compared with the EG1, the contraction amplitude and mean contraction tension of the circular and longitudinal muscles of the colon in the EG2 and EG3 were enhanced and attenuated, respectively. Thus, during UC, regulation of the expression of NOS within the MP improved the intestinal motility, thereby favoring the recovery of intestinal functions.
CONCLUSION
In UC rats, an increased number of nitrergic neurons in the colonic MP leads to the attenuation of colonic motor function. To intervene NOS activity might modulate the function of nitrergic neurons in the colonic MP and prevent colonic motor dysfunction. These results might provide clues for a novel approach to alleviate diarrhea symptoms of UC patients.
Topics: Animals; Male; Rats; Colitis, Ulcerative; Colon; Dextran Sulfate; Drinking Water; Gastrointestinal Motility; Nitrergic Neurons; Nitric Oxide; Nitric Oxide Synthase; omega-N-Methylarginine; Thrombin; Trifluoroacetic Acid
PubMed: 36157548
DOI: 10.3748/wjg.v28.i29.3854 -
PloS One 2022The endothelium maintains and regulates vascular homeostasis mainly by balancing interplay between vasorelaxation and vasoconstriction via regulating Nitric Oxide (NO)...
The endothelium maintains and regulates vascular homeostasis mainly by balancing interplay between vasorelaxation and vasoconstriction via regulating Nitric Oxide (NO) availability. Endothelial nitric oxide synthase (eNOS) is one of three NOS isoforms that catalyses the synthesis of NO to regulate endothelial function. However, eNOS's role in the regulation of endothelial function, such as cell proliferation and migration remain unclear. To gain a better understanding, we genetically knocked down eNOS in cultured endothelial cells using sieNOS and evaluated cell proliferation, migration and also tube forming potential in vitro. To our surprise, loss of eNOS significantly induced endothelial cell proliferation, which was associated with significant downregulation of both cell cycle inhibitor p21 and cell proliferation antigen Ki-67. Knockdown of eNOS induced cell migration but inhibited formation of tube-like structures in vitro. Mechanistically, loss of eNOS was associated with activation of MAPK/ERK and inhibition of PI3-K/AKT signaling pathway. On the contrary, pharmacologic inhibition of eNOS by inhibitors L-NAME or L-NMMA, inhibited cell proliferation. Genetic and pharmacologic inhibition of eNOS, both promoted endothelial cell migration but inhibited tube-forming potential. Our findings confirm that eNOS regulate endothelial function by inversely controlling endothelial cell proliferation and migration, and by directly regulating its tube-forming potential. Differential results obtained following pharmacologic versus genetic inhibition of eNOS indicates a more complex mechanism behind eNOS regulation and activity in endothelial cells, warranting further investigation.
Topics: Cells, Cultured; Endothelial Cells; Endothelium; Ki-67 Antigen; NG-Nitroarginine Methyl Ester; Nitric Oxide; Nitric Oxide Synthase Type III; Protein Isoforms; Proto-Oncogene Proteins c-akt; omega-N-Methylarginine
PubMed: 36149900
DOI: 10.1371/journal.pone.0274487 -
Clinical Hemorheology and... 2022Exercise-induced impairment of blood fluidity is considered to be associated with thrombosis development. However, the effects of L-arginine on blood fluidity after...
BACKGROUND
Exercise-induced impairment of blood fluidity is considered to be associated with thrombosis development. However, the effects of L-arginine on blood fluidity after exercise remain unclear.
OBJECTIVE
We investigated the mechanisms of impaired blood fluidity after high-intensity exercise, and examined whether L-arginine improves exercise-induced blood fluidity impairment in vitro.
METHODS
Ten healthy male participants performed 15 minutes of ergometer exercise at 70% of their peak oxygen uptake levels. Blood samples were obtained before and after exercise. L-arginine and NG-monomethyl-L-arginine acetate (L-NMMA)-a nitric oxide (NO) synthase inhibitor-were added to the post-exercise blood samples. Using Kikuchi's microchannel method, we measured the blood passage time, percentage of obstructed microchannels, and the number of adherent white blood cells (WBCs) on the microchannel terrace.
RESULTS
Exercise increased the hematocrit levels. The blood passage times, percentage of obstructed microchannels, and the number of adherent WBCs on the microchannel terrace increased after exercise; however, they decreased in a dose-dependent manner after the addition of L-arginine. L-NMMA inhibited the L-arginine-induced decrease in blood passage time.
CONCLUSIONS
High-intensity exercise impairs blood fluidity by inducing hemoconcentration along with increasing platelet aggregation and WBC adhesion. The L-arginine-NO pathway improves blood fluidity impairment after high-intensity exercise in vitro.
Topics: Humans; Male; omega-N-Methylarginine; Nitric Oxide; Arginine; Exercise; Leukocytes; Platelet Aggregation
PubMed: 35599472
DOI: 10.3233/CH-211201 -
The Journal of Physiology Mar 2022Cerebrovascular CO reactivity (CVR) is often considered a bioassay of cerebrovascular endothelial function. We recently introduced a test of cerebral shear-mediated...
Cerebrovascular CO reactivity (CVR) is often considered a bioassay of cerebrovascular endothelial function. We recently introduced a test of cerebral shear-mediated dilatation (cSMD) that may better reflect endothelial function. We aimed to determine the nitric oxide (NO)-dependency of CVR and cSMD. Eleven volunteers underwent a steady-state CVR test and transient CO test of cSMD during intravenous infusion of the NO synthase inhibitor N -monomethyl-l-arginine (l-NMMA) or volume-matched saline (placebo; single-blinded and counter-balanced). We measured cerebral blood flow (CBF; duplex ultrasound), intra-arterial blood pressure and . Paired arterial and jugular venous blood sampling allowed for the determination of trans-cerebral NO exchange (ozone-based chemiluminescence). l-NMMA reduced arterial NO by ∼25% versus saline (74.3 ± 39.9 vs. 98.1 ± 34.2 nM; P = 0.03). The steady-state CVR (20.1 ± 11.6 nM/min at baseline vs. 3.2 ± 16.7 nM/min at +9 mmHg ; P = 0.017) and transient cSMD tests (3.4 ± 5.9 nM/min at baseline vs. -1.8 ± 8.2 nM/min at 120 s post-CO ; P = 0.044) shifted trans-cerebral NO exchange towards a greater net release (a negative value indicates release). Although this trans-cerebral NO release was abolished by l-NMMA, CVR did not differ between the saline and l-NMMA trials (57.2 ± 14.6 vs. 54.1 ± 12.1 ml/min/mmHg; P = 0.49), nor did l-NMMA impact peak internal carotid artery dilatation during the steady-state CVR test (6.2 ± 4.5 vs. 6.2 ± 5.0% dilatation; P = 0.960). However, l-NMMA reduced cSMD by ∼37% compared to saline (2.91 ± 1.38 vs. 4.65 ± 2.50%; P = 0.009). Our findings indicate that NO is not an obligatory regulator of steady-state CVR. Further, our novel transient CO test of cSMD is largely NO-dependent and provides an in vivo bioassay of NO-mediated cerebrovascular function in humans. KEY POINTS: Emerging evidence indicates that a transient CO stimulus elicits shear-mediated dilatation of the internal carotid artery, termed cerebral shear-mediated dilatation. Whether or not cerebrovascular reactivity to a steady-state CO stimulus is NO-dependent remains unclear in humans. During both a steady-state cerebrovascular reactivity test and a transient CO test of cerebral shear-mediated dilatation, trans-cerebral nitrite exchange shifted towards a net release indicating cerebrovascular NO production; this response was not evident following intravenous infusion of the non-selective NO synthase inhibitor N -monomethyl-l-arginine. NO synthase blockade did not alter cerebrovascular reactivity in the steady-state CO test; however, cerebral shear-mediated dilatation following a transient CO stimulus was reduced by ∼37% following intravenous infusion of N -monomethyl-l-arginine. NO is not obligatory for cerebrovascular reactivity to CO , but is a key contributor to cerebral shear-mediated dilatation.
Topics: Carbon Dioxide; Cerebrovascular Circulation; Dilatation; Enzyme Inhibitors; Humans; Nitric Oxide; Nitric Oxide Synthase; Nitrogen Dioxide; omega-N-Methylarginine
PubMed: 34904229
DOI: 10.1113/JP282427 -
The Journal of Physiology Jan 2022
Topics: Cerebrovascular Circulation; Nitric Oxide Synthase; omega-N-Methylarginine
PubMed: 34863039
DOI: 10.1113/JP282475 -
American Journal of Physiology. Heart... Jan 2022Central adiposity is associated with greater sympathetic support of blood pressure. β-adrenergic receptors (β-AR) buffer sympathetically mediated vasoconstriction and...
Central adiposity is associated with greater sympathetic support of blood pressure. β-adrenergic receptors (β-AR) buffer sympathetically mediated vasoconstriction and β-AR-mediated vasodilation is attenuated in preclinical models of obesity. With this information, we hypothesized β-AR vasodilation would be lower in obese compared with normal weight adults. Because β-AR vasodilation in normal weight adults is limited by cyclooxygenase (COX) restraint of nitric oxide synthase (NOS), we further explored the contributions of COX and NOS to β-AR vasodilation in this cohort. Forearm blood flow (FBF, Doppler ultrasound) and mean arterial blood pressure (MAP, brachial arterial catheter) were measured and forearm vascular conductance (FVC) was calculated (FVC = FBF/MAP). The rise in FVC from baseline (ΔFVC) was quantified during graded brachial artery infusion of isoproterenol (Iso, 1-12 ng/100 g/min) in normal weight ( = 36) and adults with obesity ( = 22) (18-40 yr old). In a subset of participants, Iso-mediated vasodilation was examined before and during inhibition of NOS [-monomethyl-l-arginine (l-NMMA)], COX (ketorolac), and NOS + COX (l-NMMA + ketorolac). Iso-mediated increases in FVC did not differ between groups ( = 0.57). l-NMMA attenuated Iso-mediated ΔFVC in normal weight ( = 0.03) but not adults with obesity ( = 0.27). In normal weight adults, ketorolac increased Iso-mediated ΔFVC ( < 0.01) and this response was lost with concurrent l-NMMA ( = 0.67). In contrast, neither ketorolac ( = 0.81) nor ketorolac + l-NMMA ( = 0.40) altered Iso-mediated ΔFVC in adults with obesity. Despite shifts in COX and NOS, β-AR vasodilation is preserved in young adults with obesity. These data highlight the presence of a compensatory shift in microvascular control mechanisms in younger humans with obesity. We examined β-adrenergic receptor-mediated vasodilation in skeletal muscle of humans with obesity and normal weight. Results show that despite shifts in the contribution of cyclooxygenase and nitric oxide synthase, β-adrenergic-mediated vasodilation is relatively preserved in young, otherwise healthy adults with obesity. These data highlight the presence of subclinical changes in microvascular control mechanisms early in the obesity process and suggest duration of obesity and/or the addition of primary aging may be necessary for overt dysfunction.
Topics: Adrenergic beta-Agonists; Adult; Blood Vessels; Cyclooxygenase Inhibitors; Female; Humans; Isoproterenol; Ketorolac; Male; Muscle, Skeletal; Nitric Oxide Synthase Type III; Obesity; Prostaglandin-Endoperoxide Synthases; Receptors, Adrenergic, beta; Vasodilation; omega-N-Methylarginine
PubMed: 34738833
DOI: 10.1152/ajpheart.00449.2021