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American Journal of Physiology. Heart... Jun 2016Nitric oxide (NO) at different concentrations may promote or inhibit tumor growth and metastasis under various conditions. To test the hypothesis that tumor cells prefer...
Nitric oxide (NO) at different concentrations may promote or inhibit tumor growth and metastasis under various conditions. To test the hypothesis that tumor cells prefer to adhere to the locations with a higher endothelial NO production in intact microvessels under physiological flows and to further test that inhibiting NO production decreases tumor cell adhesion, we used intravital fluorescence microscopy to measure NO production and tumor cell adhesion in postcapillary venules of rat mesentery under normal and reduced flow conditions, and in the presence of an endothelial nitric oxide synthase (eNOS) inhibitor, N(G)-monomethyl-l-arginine (l-NMMA). Rats (SD, 250-300 g) were anesthetized. A midline incision (∼2 inch) was made in the abdominal wall, and the mesentery was taken out from the abdominal cavity and spread over a coverslip for the measurement. An individual postcapillary venule (35-50 μm) was first loaded with 4,5-diaminofluorescein diacetate (DAF-2 DA), a fluorescent indictor for NO. Then the DAF-2 intensity was measured for 30 min under a normal or reduced flow velocity, with and without perfusion with MDA-MB-231 breast cancer cells, and in the presence of l-NMMA. We found that tumor cells prefer to adhere to the microvessel locations with a higher NO production such as curved portions. Inhibition of eNOS by l-NMMA attenuated the flow-induced NO production and reduced tumor cell adhesion. We also found that l-NMMA treatment for ∼40 min reduced microvessel permeability to albumin. Our results suggest that inhibition of eNOS is a good approach to preventing tumor cell adhesion to intact microvessels under physiological flows.
Topics: Animals; Breast Neoplasms; Cell Adhesion; Cell Line, Tumor; Enzyme Inhibitors; Female; Humans; Mesentery; Nitric Oxide Synthase Type III; Rats; Rats, Sprague-Dawley; omega-N-Methylarginine
PubMed: 27059076
DOI: 10.1152/ajpheart.00109.2016 -
British Journal of Clinical Pharmacology Oct 2014A major feature of endothelial dysfunction is reduced endothelium-dependent vasodilation, which in ageing may be due to decreased production of endothelial prostacyclin,...
AIM
A major feature of endothelial dysfunction is reduced endothelium-dependent vasodilation, which in ageing may be due to decreased production of endothelial prostacyclin, or nitric oxide (NO), or both.
METHOD
We tested this hypothesis in 12 younger (age 18-38 years, six women) and 12 older healthy adults (age 55-73 years, six post-menopausal women). Endothelium-dependent vasodilation was assessed by the forearm vascular conductance (FVC) response to intra-arterial acetylcholine (ACh) (0.5, 1.0, 2.0, 4.0 μg dl(-1) forearm tissue min(-1) ) before and 90 min after inhibition of the enzyme cyclo-oxygenase-2 (COX-2) with oral celecoxib (400 mg), followed by the addition of endothelial NO synthase inhibition with intra-arterial N(G) -monomethyl-l arginine acetate (L-NMMA).
RESULTS
Ageing was associated with a significantly reduced FVC response to ACh (P = 0.009, age-by-dose interaction; highest dose FVC ± SEM in ageing: 11.2 ± 1.4 vs. younger: 17.7 ± 2.4 units, P = 0.02). Celecoxib did not reduce resting FVC or the responses to ACh in any group. L-NMMA significantly reduced resting FVC and the responses to ACh in all groups, and absolute FVC values following L-NMMA were similar between groups.
CONCLUSION
In healthy normotensive younger and older adults, there is minimal contribution of prostacyclin to ACh-mediated vasodilation, yet the NO component of vasodilation is reduced with ageing. In the clinical context, these findings suggest that acute administration of medications that inhibit prostacyclin (i.e. COX-2 inhibitors) evoke modest vascular consequences in healthy persons. Additional studies are necessary to test whether chronic use of COX-2 medications reduces endothelium dependent vasodilation in older persons with or without cardiovascular risk factors.
Topics: Acetylcholine; Adolescent; Adult; Age Factors; Aged; Cyclooxygenase 2 Inhibitors; Endothelium, Vascular; Female; Humans; Male; Middle Aged; Nitric Oxide; Vasodilation; Young Adult; omega-N-Methylarginine
PubMed: 24698105
DOI: 10.1111/bcp.12397 -
The Journal of Physiology Dec 2017People with insulin resistance or type 2 diabetes can substantially increase their skeletal muscle glucose uptake during exercise and insulin sensitivity after exercise....
KEY POINTS
People with insulin resistance or type 2 diabetes can substantially increase their skeletal muscle glucose uptake during exercise and insulin sensitivity after exercise. Skeletal muscle nitric oxide (NO) is important for glucose uptake during exercise, although how prior exercise increases insulin sensitivity is unclear. In the present study, we examined whether NO is necessary for normal increases in skeletal muscle insulin sensitivity after contraction ex vivo in mouse muscle. The present study uncovers, for the first time, a novel role for NO in the insulin sensitizing effects of ex vivo contraction, which is independent of blood flow.
ABSTRACT
The factors regulating the increase in skeletal muscle insulin sensitivity after exercise are unclear. We examined whether nitric oxide (NO) is required for the increase in insulin sensitivity after ex vivo contractions. Isolated C57BL/6J mouse EDL muscles were contracted for 10 min or remained at rest (basal) with or without the NO synthase (NOS) inhibition (N -monomethyl-l-arginine; l-NMMA; 100 μm). Then, 3.5 h post contraction/basal, muscles were exposed to saline or insulin (120 μU ml ) with or without l-NMMA during the last 30 min. l-NMMA had no effect on basal skeletal muscle glucose uptake. The increase in muscle glucose uptake with insulin (57%) was significantly (P < 0.05) greater after prior contraction (140% increase). NOS inhibition during the contractions had no effect on this insulin-sensitizing effect of contraction, whereas NOS inhibition during insulin prevented the increase in skeletal muscle insulin sensitivity post-contraction. Soluble guanylate cyclase inhibition, protein kinase G (PKG) inhibition or cyclic nucleotide phosphodiesterase inhibition each had no effect on the insulin-sensitizing effect of prior contraction. In conclusion, NO is required for increases in insulin sensitivity several hours after contraction of mouse skeletal muscle via a cGMP/PKG independent pathway.
Topics: 2',3'-Cyclic-Nucleotide Phosphodiesterases; Animals; Cells, Cultured; Cyclic GMP-Dependent Protein Kinases; Glucose; Guanylate Cyclase; Insulin; Male; Mice; Mice, Inbred C57BL; Muscle Contraction; Muscle Fibers, Skeletal; Nitric Oxide; Nitric Oxide Synthase; Signal Transduction; omega-N-Methylarginine
PubMed: 29071734
DOI: 10.1113/JP275133 -
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 -
Hypertension (Dallas, Tex. : 1979) Sep 2018Renal denervation (RDN) has been shown to restore endogenous neuronal nitric oxide synthase (nNOS) in the paraventricular nucleus (PVN) and reduce sympathetic drive...
Renal denervation (RDN) has been shown to restore endogenous neuronal nitric oxide synthase (nNOS) in the paraventricular nucleus (PVN) and reduce sympathetic drive during chronic heart failure (CHF). The purpose of the present study was to assess the contribution of afferent renal nerves to the nNOS-mediated sympathetic outflow within the PVN in rats with CHF. CHF was induced in rats by ligation of the left coronary artery. Four weeks after surgery, selective afferent RDN (A-RDN) was performed by bilateral perivascular application of capsaicin on the renal arteries. Seven days after intervention, nNOS protein expression, nNOS immunostaining signaling, and diaphorase-positive stained cells were significantly decreased in the PVN of CHF rats, changes that were reversed by A-RDN. A-RDN reduced basal lumbar sympathetic nerve activity in rats with CHF (8.5%±0.5% versus 17.0%±1.2% of max). Microinjection of nNOS inhibitor L-NMMA (L-N-monomethyl arginine citrate) into the PVN produced a blunted increase in lumbar sympathetic nerve activity in rats with CHF. This response was significantly improved after A-RDN (Δ lumbar sympathetic nerve activity: 25.7%±2.4% versus 11.2%±0.9%). Resting afferent renal nerves activity was substantially increased in CHF compared with sham rats (56.3%±2.4% versus 33.0%±4.7%). These results suggest that intact afferent renal nerves contribute to the reduction of nNOS in the PVN. A-RDN restores nNOS and thus attenuates the sympathoexcitation. Also, resting afferent renal nerves activity is elevated in CHF rats, which may highlight a crucial neural mechanism arising from the kidney in the maintenance of enhanced sympathetic drive in CHF.
Topics: Afferent Pathways; Animals; Capsaicin; Chronic Disease; Denervation; Enzyme Inhibitors; Heart Failure; Kidney; Male; Nitric Oxide Synthase Type I; Paraventricular Hypothalamic Nucleus; Rats, Sprague-Dawley; Sensory System Agents; Sympathetic Nervous System; omega-N-Methylarginine
PubMed: 30012866
DOI: 10.1161/HYPERTENSIONAHA.118.11071 -
EuroIntervention : Journal of EuroPCR... Apr 2015To investigate in vivo relationships between segmental wall shear stress (WSS), endothelium-dependent vasoreactivity and arterial remodelling.
AIMS
To investigate in vivo relationships between segmental wall shear stress (WSS), endothelium-dependent vasoreactivity and arterial remodelling.
METHODS AND RESULTS
Twenty-four patients with minor angiographic coronary arterial disease (≤30% stenosis severity) underwent intracoronary (IC) salbutamol provocation during intravascular ultrasound (IVUS)-upon-Doppler guidewire imaging. Macrovascular response (change in segmental lumen volume [SLV] at baseline and following IC salbutamol), plaque burden (percent atheroma volume [PAV]), remodelling indices (RI), eccentricity indices (EI) and WSS were evaluated in 179 consecutive 5 mm coronary segments. Baseline WSS was directly related to endothelium-dependent epicardial coronary vasomotion (% change SLV, coefficient 17.2, p=0.004), and inversely related to RI (coefficient -0.23, p=0.02) and EI (coefficient -10.0, p=0.001). Baseline WSS was lower in segments displaying endothelial dysfunction (defined as any change in SLV ≤0) compared with preserved function (0.66±0.33 vs. 0.71±0.22 N/m2, p=0.046). Independent of plaque burden, segments with the lowest tertile of WSS displayed less vasodilatation, or vasoconstriction, than segments with the highest tertile of WSS. Higher plaque burden segments harbouring the lowest tertiles of WSS displayed vasoconstriction, expansive arterial remodelling and greater plaque eccentricity.
CONCLUSIONS
In patients with stable coronary syndromes and minor angiographic coronary disease, coronary segments with lower in vivo WSS values display functional and morphological features of plaque vulnerability.
Topics: Adrenergic beta-2 Receptor Agonists; Albuterol; Coronary Angiography; Coronary Artery Disease; Coronary Stenosis; Coronary Vessels; Endothelium, Vascular; Enzyme Inhibitors; Female; Humans; Male; Middle Aged; Severity of Illness Index; Shear Strength; Ultrasonography, Doppler; Ultrasonography, Interventional; Vascular Remodeling; Vasodilation; omega-N-Methylarginine
PubMed: 24425248
DOI: 10.4244/EIJV10I12A249 -
Applied Physiology, Nutrition, and... Jul 2015High-fat diets are associated with an increased risk of cardiovascular disease. A potential underlying mechanism for the increased cardiovascular risk is endothelial...
High-fat diets are associated with an increased risk of cardiovascular disease. A potential underlying mechanism for the increased cardiovascular risk is endothelial dysfunction. Nitric oxide (NO)-mediated endothelium-dependent vasodilation is critical in the regulation of vascular tone and overall vascular health. The aim of this study was to determine the influence of dietary fat intake on endothelium-dependent vasodilation. Forty-four middle-aged and older sedentary, healthy adults were studied: 24 consumed a lower fat diet (LFD; 29% ± 1% calories from fat) and 20 consumed a high-fat diet (HFD; 41% ± 1% calories from fat). Four-day diet records were used to assess fat intake, and classifications were based on American Heart Association guidelines (<35% of total calories from fat). Forearm blood flow (FBF) responses to acetylcholine, in the absence and presence of the endothelial NO synthase inhibitor N(G)-monomethyl-l-arginine (L-NMMA), as well as responses to sodium nitroprusside were determined by plethysmography. The FBF response to acetylcholine was lower (∼15%; P < 0.05) in the HFD group (4.5 ± 0.2 to 12.1 ± 0.8 mL/100 mL tissue/min) than in the LFD group (4.6 ± 0.2 to 14.4 ± 0.6 mL/100 mL tissue/min). L-NMMA significantly reduced the FBF response to acetylcholine in the LFD group (∼25%) but not in the HFD group. There were no differences between groups in the vasodilator response to sodium nitroprusside. These data indicate that a high-fat diet is associated with endothelium-dependent vasodilator dysfunction due, in part, to diminished NO bioavailability. Impaired NO-mediated endothelium-dependent vasodilation may contribute to the increased cardiovascular risk with high dietary fat intake.
Topics: Acetylcholine; Adult; Aged; Analysis of Variance; Diet, High-Fat; Dietary Fats; Endothelium, Vascular; Feeding Behavior; Female; Humans; Male; Middle Aged; Nitric Oxide Synthase Type III; Nitroprusside; Plethysmography; Risk Factors; Vasodilation; omega-N-Methylarginine
PubMed: 26058441
DOI: 10.1139/apnm-2015-0006 -
American Journal of Physiology. Heart... Aug 2014The incidence of cardiovascular disease increases progressively with age, but aging may affect men and women differently. Age-associated changes in vascular structure...
The incidence of cardiovascular disease increases progressively with age, but aging may affect men and women differently. Age-associated changes in vascular structure and function may manifest in impaired nutritive blood flow, although the regulation of nutritive blood flow in healthy aging is not well understood. The purpose of this study was to determine if nitric oxide (NO)-mediated or α-adrenergic-mediated regulation of nutritive skeletal muscle blood flow is impaired with advanced age, and if exercise training improves age-related deficiencies. Nutritive blood flow was monitored in the vastus lateralis of healthy young and aged men and women via the microdialysis-ethanol technique prior to and following seven consecutive days of exercise training. NO-mediated and α-adrenergic-mediated regulation of nutritive blood flow was assessed by microdialysis perfusion of acetylcholine, sodium nitroprusside, N(G)-monomethyl-L-arginine, norepinephrine, or phentolamine. Pretraining nutritive blood flow was attenuated in aged compared with young women (7.39 ± 1.5 vs. 15.5 ± 1.9 ml·100 g(−1)·min(−1), P = 0.018), but not aged men (aged 13.5 ± 3.7 vs. young 9.4 ± 1.3 ml·100 g(−1)·min(−1), P = 0.747). There were no age-associated differences in NO-mediated or α-adrenergic-mediated nutritive blood flow. Exercise training increased resting nutritive blood flow only in young men (9.4 ± 1.3 vs. 19.7 ml·100 g(−1)·min(−1), P = 0.005). The vasodilatory effect of phentolamine was significantly reduced following exercise training only in young men (12.3 ± 6.14 vs. −3.68 ± 3.26 ml·100 g(−1)·min(−1), P = 0.048). In conclusion, the age-associated attenuation of resting nutritive skeletal muscle blood flow was specific to women, while the exercise-induced alleviation of α-adrenergic mediated vasoconstriction that was specific to young men suggests an age-associated modulation of the sympathetic response to exercise training.
Topics: Acetylcholine; Adrenergic alpha-Agonists; Adrenergic alpha-Antagonists; Adult; Aged; Aging; Enzyme Inhibitors; Exercise; Female; Humans; Male; Middle Aged; Muscle, Skeletal; Nitric Oxide Donors; Nitroprusside; Norepinephrine; Phentolamine; Regional Blood Flow; Sex Factors; Vasoconstriction; Vasodilator Agents; omega-N-Methylarginine
PubMed: 24951753
DOI: 10.1152/ajpheart.00247.2014 -
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 -
Blood Jan 2015Nitric oxide (NO) exerts vasodilatatory, antiplatelet, antioxidant, and antiproliferative effects. Endothelium-derived NO has been shown to be of crucial importance in...
Nitric oxide (NO) exerts vasodilatatory, antiplatelet, antioxidant, and antiproliferative effects. Endothelium-derived NO has been shown to be of crucial importance in cardiovascular protection, whereas evidence that NO is synthesized by platelets and regulates platelet function is still controversial. By using a sensitive and specific fluorescent probe, 4-amino-5-methylamino-2',7'-difluorofluorescein diacetate (DAF-FM), we visualized NO production in individual platelets undergoing adhesion on a collagen substrate under flow conditions. NO production, monitored in real time, was dependent on the shear rates applied, increasing with the raising of the shear rates. Furthermore, NO production increased in the presence of l-arginine (nitric-oxide synthase [NOS] substrate), and it decreased in the presence of L-NG-monomethyl arginine (L-NMMA) (NOS inhibitor) but not of D-NG-monomethyl arginine (D-NMMA) (L-NMMA-inactive enantiomer). Platelet deposition, measured with mepacrine-labeled platelets, was inversely related to NO production. A correlation was evident between Ca(++) elevation and NO production, suggesting that platelet NO formation is triggered by intracytoplasmic Ca(++) elevation. Simultaneous measurement of NO and Ca(++) indicated that NO production in individual platelets is preceded by Ca(++) elevations, with a lag phase of 33 ± 9.5 s. Our studies provide the first direct demonstration of platelet NO production triggered by the interaction with an activating surface under flow and suggest that intraplatelet Ca(++) elevation elicits the production of NO which, in turn, modulates thrombus size.
Topics: Animals; Blood Flow Velocity; Blood Platelets; Calcium; Collagen; Enzyme Inhibitors; Fluoresceins; Male; Mice; Mice, Knockout; Nitric Oxide; Platelet Adhesiveness; Quinacrine; omega-N-Methylarginine
PubMed: 25480660
DOI: 10.1182/blood-2014-06-579474