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American Journal of Physiology. Heart... Apr 2012The purpose of this study was to determine if tonic restrain of blood pressure by nitric oxide (NO) is impaired early in the development of hypertension. Impaired NO...
The purpose of this study was to determine if tonic restrain of blood pressure by nitric oxide (NO) is impaired early in the development of hypertension. Impaired NO function is thought to contribute to hypertension, but it is not clear if this is explained by direct effects of NO on vascular tone or indirect modulation of sympathetic activity. We determined the blood pressure effect of NO synthase inhibition with N(ω)-monomethyl-l-arginine (L-NMMA) during autonomic blockade with trimethaphan to eliminate baroreflex buffering and NO modulation of autonomic tone. In this setting, impaired NO modulation of vascular tone would be reflected as a blunted pressor response to L-NMMA. We enrolled a total of 66 subjects (39 ± 1.3 yr old, 30 females), 20 normotensives, 20 prehypertensives (blood pressure between 120/80 and 140/90 mmHg), 17 hypertensives, and 9 smokers (included as "positive" controls of impaired NO function). Trimethaphan normalized blood pressure in hypertensives, suggesting increased sympathetic tone contributing to hypertension. In contrast, L-NMMA produced similar increases in systolic blood pressure in normal, prehypertensive, and hypertensive subjects (31 ± 2, 32 ± 2, and 30 ± 3 mmHg, respectively), whereas the response of smokers was blunted (16 ± 5 mmHg, P = 0.012). Our results suggest that sympathetic activity plays a role in hypertension. NO tonically restrains blood pressure by ∼30 mmHg, but we found no evidence of impaired modulation by NO of vascular tone contributing to the early development of hypertension. If NO deficiency contributes to hypertension, it is likely to be through its modulation of the autonomic nervous system, which was excluded in this study.
Topics: Adolescent; Adult; Aging; Baroreflex; Blood Pressure; Enzyme Inhibitors; Female; Heart Rate; Humans; Hypertension; Male; Middle Aged; Muscle Tonus; Muscle, Smooth, Vascular; Nicotinic Antagonists; Nitric Oxide; Nitric Oxide Synthase Type III; Receptors, Nicotinic; Smoking; Sympathetic Nervous System; Trimethaphan; Young Adult; omega-N-Methylarginine
PubMed: 22287587
DOI: 10.1152/ajpheart.01020.2011 -
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 -
Arteriosclerosis, Thrombosis, and... Jun 2014Abnormalities in nitric oxide (NO) bioavailability have been reported in blacks. Whether there are differences in endothelium-derived hyperpolarizing factor (EDHF) in... (Comparative Study)
Comparative Study
OBJECTIVE
Abnormalities in nitric oxide (NO) bioavailability have been reported in blacks. Whether there are differences in endothelium-derived hyperpolarizing factor (EDHF) in addition to NO between blacks and whites and how these affect physiological vasodilation remain unknown. We hypothesized that the bioavailability of vascular NO and EDHF, at rest and with pharmacological and physiological vasodilation, varies between whites and blacks.
APPROACH AND RESULTS
In 74 white and 86 black subjects without known cardiovascular disease risk factors, forearm blood flow was measured using plethysmography at rest and during inhibition of NO with N(G)-monomethyl-L-arginine and of K(+) Ca channels (EDHF) with tetraethylammonium. The reduction in resting forearm blood flow was greater with N(G)-monomethyl-L-arginine (P=0.019) and similar with tetraethylammonium in whites compared with blacks. Vasodilation with bradykinin, acetylcholine, and sodium nitroprusside was lower in blacks compared with whites (all P<0.0001). Inhibition with N(G)-monomethyl-L-arginine was greater in whites compared with blacks with bradykinin, acetylcholine, and exercise. Inhibition with tetraethylammonium was lower in blacks with bradykinin, but greater during exercise and with acetylcholine.
CONCLUSIONS
The contribution to both resting and stimulus-mediated vasodilator tone of NO is greater in whites compared with blacks. EDHF partly compensates for the reduced NO release in exercise and acetylcholine-mediated vasodilation in blacks. Preserved EDHF but reduced NO bioavailability and sensitivity characterizes the vasculature in healthy blacks.
CLINICAL TRIAL REGISTRATION URL
http://clinicaltrials.gov/. Unique identifier: NCT00166166.
Topics: Acetylcholine; Adult; Black or African American; Biological Availability; Biological Factors; Bradykinin; Exercise; Female; Forearm; Humans; Male; Middle Aged; Nitric Oxide; Nitroprusside; Potassium Channels, Calcium-Activated; Tetraethylammonium Compounds; Vascular Resistance; Vasodilation; White People; omega-N-Methylarginine
PubMed: 24675657
DOI: 10.1161/ATVBAHA.113.303136 -
Tissue & Cell Dec 2021Puerarin regulates the osteoblast differentiation of umbilical cord mesenchymal stem cells. This study, hereby, explored the effects of puerarin on the osteogenic...
Puerarin regulates the osteoblast differentiation of umbilical cord mesenchymal stem cells. This study, hereby, explored the effects of puerarin on the osteogenic differentiation of dental follicle cells (DFCs) for the first time. Rat DFCs (rDFCs) were isolated and identified. After the rDFCs were treated by Puerarin and cultured in osteogenic induction medium, the viability, osteogenic differentiation, and the activities of alkaline phosphatase (ALP) and nitric oxide (NO) were detected. Besides, the secretion of cyclic guanosine monophosphate (cGMP) and expressions of collagen I, osteocalcin (OC), osteopontin (OPN), runt-related transcription factor 2 (RUNX2), soluble guanylate cyclase (SGC), and protein kinase G 1 (PKG-1) were further determined or quantified. Puerarin enhanced the viability and osteogenic differentiation, and increased the activities of ALP, NO, and cGMP and the expressions of Collagen I, OC, OPN, RUNX2, SGC, and PKG-1 in rDFCs. After the co-treatment with puerarin and L-NMMA (NO synthase inhibitor), the promotive effects of Puerarin on cell viability, osteogenic differentiation, and the expressions of collagen I, OC, OPN, RUNX2, SGC, and PKG-1 in rDFCs were reversed by L-NMMA. Puerarin boosted the osteogenic differentiation of rDFCs by activating the NO pathway.
Topics: Alkaline Phosphatase; Animals; Animals, Newborn; Cell Differentiation; Cell Survival; Cells, Cultured; Collagen Type I; Core Binding Factor Alpha 1 Subunit; Cyclic GMP; Cyclic GMP-Dependent Protein Kinases; Dental Sac; Guanylate Cyclase; Isoflavones; Nitric Oxide; Osteocalcin; Osteogenesis; Osteopontin; Rats, Sprague-Dawley; Solubility; omega-N-Methylarginine; Rats
PubMed: 34371290
DOI: 10.1016/j.tice.2021.101601 -
Journal of Vascular Research 2014Bradykinin (BK) stimulates tissue plasminogen activator (t-PA) release from human endothelium. Although BK stimulates both nitric oxide and endothelium-derived... (Clinical Trial)
Clinical Trial
AIMS
Bradykinin (BK) stimulates tissue plasminogen activator (t-PA) release from human endothelium. Although BK stimulates both nitric oxide and endothelium-derived hyperpolarizing factor (EDHF) release, the role of EDHF in t-PA release remains unexplored. This study sought to determine the mechanisms of BK-stimulated t-PA release in the forearm vasculature of healthy human subjects.
METHODS
In 33 healthy subjects (age 40.3 ± 1.9 years), forearm blood flow (FBF) and t-PA release were measured at rest and after intra-arterial infusions of BK (400 ng/min) and sodium nitroprusside (3.2 mg/min). Measurements were repeated after intra-arterial infusion of tetraethylammonium chloride (TEA; 1 µmol/min), fluconazole (0.4 µmol·min(-1)·l(-1)), and N(G)-monomethyl-L-arginine (L-NMMA, 8 µmol/min) to block nitric oxide, and their combination in separate studies.
RESULTS
BK significantly increased net t-PA release across the forearm (p < 0.0001). Fluconazole attenuated both BK-mediated vasodilation (-23.3 ± 2.7% FBF, p < 0.0001) and t-PA release (from 50.9 ± 9.0 to 21.3 ± 8.9 ng/min/100 ml, p = 0.02). TEA attenuated FBF (-14.7 ± 3.2%, p = 0.002) and abolished BK-stimulated t-PA release (from 22.9 ± 5.7 to -0.8 ± 3.6 ng/min/100 ml, p = 0.0002). L-NMMA attenuated FBF (p < 0.0001), but did not inhibit BK-induced t-PA release (nonsignificant).
CONCLUSION
BK-stimulated t-PA release is partly due to cytochrome P450-derived epoxides and is inhibited by K(+)Ca channel blockade. Thus, BK stimulates both EDHF-dependent vasodilation and t-PA release.
Topics: Adult; Biological Factors; Bradykinin; Cytochrome P-450 Enzyme System; Female; Fluconazole; Forearm; Humans; Male; Middle Aged; Nitroprusside; Potassium Channels, Calcium-Activated; Regional Blood Flow; Tetraethylammonium; Tissue Plasminogen Activator; Vasodilation; omega-N-Methylarginine
PubMed: 24925526
DOI: 10.1159/000362666 -
Kidney International Dec 1997NG-monomethylarginine (L-NMA) and asymmetric NG, NG-dimethylarginines (ADMA) are endogenous inhibitors of cellular L-arginine uptake and/or nitric oxide (NO) synthesis...
NG-monomethylarginine (L-NMA) and asymmetric NG, NG-dimethylarginines (ADMA) are endogenous inhibitors of cellular L-arginine uptake and/or nitric oxide (NO) synthesis that are implicated in renal parenchymal and Dahl salt-sensitive hypertension. Since the L-arginine:(L-NMA + ADMA) ratio determines NO synthase (NOS) activity, we compared the immunohistochemical distribution of NOS with NG, NG-dimethylarginine dimethylaminohydrolase (DDAH), which inactivates dimethylarginines (DMA) and L-NMA by hydrolysis to L-citrulline. Neuronal NOS (nNOS) was expressed predominantly in tubular epithelial cells of macula densa (MD), endothelial NOS (eNOS) in vascular endothelial cells (EC), and inducible NOS (iNOS) quite widely in tubular epithelium, including proximal tubules (PT), thick ascending limbs of Henle (TAL), distal convoluted tubule and intercalated cells (IC) of the collecting duct. Immunostaining for DDAH was present in PT, TAL, MD, and IC, and was also present in the glomerulus, Bowman's capsule, and endothelium of blood vessels. DDAH was detected in small vesicles of TAL and PT by electron microscopic (EM) immunocytochemistry. To study the effects of methylarginines on tubuloglomerular feedback (TGF) response, vehicle or methylarginines (10(-3) M) were added to artificial tubular fluid (ATF) perfused orthogradely from the late PT at 40 nl. min-1 while assessing changes in glomerular capillary pressure from proximal stop flow pressure (PSF). Whereas the maximal TGF responses were unchanged by vehicle (delta TGF 0 +/- 0%) or symmetric DMA (SDMA; +1 +/- 2%, NS), they were enhanced by L-NMA (+22 +/- 4%, P < 0.001) and asymmetric DMA (ADMA; +28 +/- 3%, P < 0.001). Since L-arginine transport can regulate renal epithelial NO generation, methylarginines (10(-3) M) or vehicle were co-perfused orthogradely with [3H]-L-arginine from the late PT and collected at the early distal tubule to study arginine uptake from the perfused loop of Henle. All methylarginines reduced fractional loop [3H] absorption significantly (P < 0.001; vehicle, 84 +/- 6; ADMA, 49 +/- 6; SDMA, 56 +/- 6; L-NMA, 41 +/- 6%). In conclusion, sites of DDAH expression in the vasculature or nephron are all sites of expression of an isoform of NOS. L-NMA, ADMA, and SDMA all inhibit renal tubular L-arginine uptake, whereas L-NMA and ADMA, but not SDMA, enhance TGF responses. Therefore, DDAH may regulate the cellular L-arginine: methylarginine levels in specific renal cells, thereby governing cell-specific L-arginine uptake and NO generation in renal tubular epithelium.
Topics: Amidohydrolases; Animals; Arginine; Blotting, Western; Enzyme Inhibitors; Hydrolases; Kidney Glomerulus; Loop of Henle; Male; Methylation; Microscopy, Immunoelectron; Nitric Oxide Synthase; Rats; Rats, Sprague-Dawley; Tritium; omega-N-Methylarginine
PubMed: 9407505
DOI: 10.1038/ki.1997.490 -
American Journal of Physiology.... Apr 2013Contraction of intestinal myofibroblasts (IMF) contributes to the development of strictures and fistulas seen in inflammatory bowel disease, but the mechanisms that...
Contraction of intestinal myofibroblasts (IMF) contributes to the development of strictures and fistulas seen in inflammatory bowel disease, but the mechanisms that regulate tension within these cells are poorly understood. In this study we investigated the role of nitric oxide (NO) signaling in C-type natriuretic peptide (CNP)-induced relaxation of IMF. We found that treatment with ODQ, a soluble guanylyl cyclase (sGC) inhibitor, or N(G)-nitro-L-arginine (L-NNA) or N(G)-monomethyl-L-arginine (L-NMMA), inhibitors of NO production, all impaired the relaxation of human and mouse IMF in response to CNP. ODQ, L-NNA, and L-NMMA also prevented CNP-induced elevations in cGMP concentrations, and L-NNA or L-NMMA blocked CNP-induced decreases in myosin light phosphorylation. IMF isolated from transgenic mice deficient in inducible nitric oxide synthase (iNOS) had reduced relaxation responses to CNP compared with IMF from control mice and were insensitive to the effects of ODQ, L-NNA, and L-NMMA on CNP treatment. Together these data indicate that stimulation of sGC though NO produced by iNOS activation is required for maximal CNP-induced relaxation in IMF.
Topics: Animals; Cyclic GMP; Guanylate Cyclase; Humans; Mice; Muscle Relaxation; Myofibroblasts; Natriuretic Peptide, C-Type; Nitric Oxide Synthase Type II; Nitroarginine; Oxadiazoles; Quinoxalines; Receptors, Cytoplasmic and Nuclear; Soluble Guanylyl Cyclase; omega-N-Methylarginine
PubMed: 23348803
DOI: 10.1152/ajpgi.00214.2012 -
Biological Research Sep 2014Nitric oxide (NO) has been shown to be important in sperm function, and the concentration of NO appears to determine these effects. Studies have demonstrated both...
BACKGROUND
Nitric oxide (NO) has been shown to be important in sperm function, and the concentration of NO appears to determine these effects. Studies have demonstrated both positive and negative effects of NO on sperm function, but have not been able to provide a clear link between NO concentration and the extent of exposure to NO. To study the relationship between nitric oxide and sperm capacitation in vitro, and to provide a theoretical basis for the use of NO-related preparations in improving sperm motility for in vitro fertilization, we investigated the effects of NO concentration and time duration at these concentrations on in vitro sperm capacitation in both normal and abnormal sperm groups. We manipulated NO concentrations and the time duration of these concentrations using sodium nitroprusside (an NO donor) and NG-monomethyl-L-argenine (an NO synthase inhibitor).
RESULTS
Compared to the normal sperm group, the abnormal sperm group had a longer basal time to reach the appropriate concentration of NO (p < 0.001), and the duration of time at this concentration was longer for the abnormal sperm group (p < 0.001). Both the basal time and the duration of time were significantly correlated with sperm viability and percentage of progressive sperm (p < 0.001). The experimental group had a significantly higher percentage of progressive sperm than the control group (p < 0.001).
CONCLUSIONS
We hypothesize that there is a certain regularity to both NO concentration and its duration of time in regards to sperm capacitation, and that an adequate duration of time at the appropriate NO concentration is beneficial to sperm motility.
Topics: Adult; Cell Survival; Fertilization in Vitro; Humans; In Vitro Techniques; Male; Nitric Oxide; Nitric Oxide Synthase; Nitroprusside; Sperm Capacitation; Sperm Motility; Time Factors; omega-N-Methylarginine
PubMed: 25299622
DOI: 10.1186/0717-6287-47-44 -
American Journal of Physiology.... Jul 2012Nitric oxide (NO) and prostaglandins (PG) together play a role in regulating blood flow during exercise. NO also regulates mitochondrial oxygen consumption through... (Clinical Trial)
Clinical Trial
Nitric oxide (NO) and prostaglandins (PG) together play a role in regulating blood flow during exercise. NO also regulates mitochondrial oxygen consumption through competitive binding to cytochrome-c oxidase. Indomethacin uncouples and inhibits the electron transport chain in a concentration-dependent manner, and thus, inhibition of NO and PG synthesis may regulate both muscle oxygen delivery and utilization. The purpose of this study was to examine the independent and combined effects of NO and PG synthesis blockade (L-NMMA and indomethacin, respectively) on mitochondrial respiration in human muscle following knee extension exercise (KEE). Specifically, this study examined the physiological effect of NO, and the pharmacological effect of indomethacin, on muscle mitochondrial function. Consistent with their mechanism of action, we hypothesized that inhibition of nitric oxide synthase (NOS) and PG synthesis would have opposite effects on muscle mitochondrial respiration. Mitochondrial respiration was measured ex vivo by high-resolution respirometry in saponin-permeabilized fibers following 6 min KEE in control (CON; n = 8), arterial infusion of N(G)-monomethyl-L-arginine (L-NMMA; n = 4) and Indo (n = 4) followed by combined inhibition of NOS and PG synthesis (L-NMMA + Indo, n = 8). ADP-stimulated state 3 respiration (OXPHOS) with substrates for complex I (glutamate, malate) was reduced 50% by Indo. State 3 O(2) flux with complex I and II substrates was reduced less with both Indo (20%) and L-NMMA + Indo (15%) compared with CON. The results indicate that indomethacin reduces state 3 mitochondrial respiration primarily at complex I of the respiratory chain, while blockade of NOS by L-NMMA counteracts the inhibition by Indo. This effect on muscle mitochondria, in concert with a reduction of blood flow accounts for in vivo changes in muscle O(2) consumption during combined blockade of NOS and PG synthesis.
Topics: Electron Transport Chain Complex Proteins; Exercise; Humans; Indomethacin; Male; Mitochondria, Muscle; Muscle, Skeletal; Nitric Oxide; Oxygen; Oxygen Consumption; Prostaglandin Antagonists; Regional Blood Flow; Young Adult; omega-N-Methylarginine
PubMed: 22552792
DOI: 10.1152/ajpregu.00044.2012 -
Journal of Vascular Surgery Jul 2001The hypothesis to be tested was that diminished bioavailable nitric oxide (NO) affects matrix metalloproteinase (MMP) expression and activation in vascular smooth muscle...
OBJECTIVE
The hypothesis to be tested was that diminished bioavailable nitric oxide (NO) affects matrix metalloproteinase (MMP) expression and activation in vascular smooth muscle cells (SMCs).
METHODS
Cultivated rat aortic SMCs (RA-SMCs) were exposed to increasing concentrations of L-N-monomethyl arginine (L-NMMA), a nonselective inhibitor of NO synthase, in the presence of proinflammatory cytokines (50 ng/mL interleukin [IL]-1beta, 50 ng/mL interferon-gamma, and 30 microg/mL lipopolysaccharide). Nitrite and nitrate, two of the final end products of NO metabolism, were measured in media collected at 48 hours with the use of the Saville assay (n = 4). MMP activity was measured with 1% gelatin zymography (n = 4). In separate experiments in which 2 ng/mL of IL-1beta and L-NMMA was used, MMP protein and messenger RNA (mRNA) levels were determined with Western blot analysis (n = 3) and semiquantitative reverse transcriptase-polymerase chain reaction (n = 3), respectively. Data were analyzed with nonparametric analysis of variance.
RESULTS
Increasing concentrations of the NO synthase inhibitor L-NMMA caused a dose-dependent decrease (P <.05) in nitrite and nitrate production by RA-SMCs after cytokine exposure. Zymography documented an early dosedependent increase (P <.05 compared with cytokines alone) in 92-kd MMP activity, with no significant changes in 72-kd MMP activity after treatment with L-NMMA (P >.05 compared with cytokines alone). Reverse transcriptase-polymerase chain reaction and Western blot analysis revealed that the addition of L-NMMA to IL-1beta-stimulated RA-SMCs led to significant increases in MMP-9 mRNA (n = 3, P <.01 for 1.0 mmol/L L-NMMA) and MMP-9 protein levels (n = 3, P <.05), respectively. No differences in MMP-2 mRNA or protein levels were demonstrated.
CONCLUSIONS
Inhibition of cytokine-induced NO expression in RA-SMCs is associated with a selective, dose-dependent increase in MMP-9 expression and synthesis. These findings suggest that alterations in local NO synthesis may influence MMP-9-dependent vessel wall damage.
Topics: Animals; Aorta; Blotting, Western; Cells, Cultured; Electrophoresis, Polyacrylamide Gel; Enzyme Inhibitors; Male; Matrix Metalloproteinase 9; Muscle, Smooth, Vascular; Nitric Oxide; RNA, Messenger; Rats; Rats, Sprague-Dawley; Reverse Transcriptase Polymerase Chain Reaction; omega-N-Methylarginine
PubMed: 11436078
DOI: 10.1067/mva.2001.115598