scholarly journals Endothelium-Derived Hyperpolarizing Factor (EDHF) Mediates Acetylsalicylic Acid (Aspirin) Vasodilation of Pregnant Rat Mesenteric Arteries

2021 ◽  
Vol 22 (18) ◽  
pp. 10162
Author(s):  
Helga Helgadóttir ◽  
Teresa Tropea ◽  
Sveinbjörn Gizurarson ◽  
Maurizio Mandalà
Keyword(s):  
Acetylsalicylic Acid ◽  
Molecular Mechanism ◽  
Major Complication ◽  
Mesenteric Arteries ◽  
Resistance Arteries ◽  
Pregnant Rat ◽  
Calcium Activated Potassium Channels ◽  
Oxide Synthase ◽  
First Time ◽  
Small Conductance

Acetylsalicylic acid (aspirin) exhibits a broad range of activities, including analgesic, antipyretic, and antiplatelet properties. Recent clinical studies also recommend aspirin prophylaxis in women with a high risk of pre-eclampsia, a major complication of pregnancy characterized by hypertension. We investigated the effect of aspirin on mesenteric resistance arteries and found outdiscovered the molecular mechanism underlying this action. Aspirin (10−12–10−6 M) was tested on pregnant rat mesenteric resistance arteries by a pressurized arteriography. Aspirin was investigated in the presence of several inhibitors of: (a) nitric oxide synthase (L-NAME 2 × 10−4 M); (b) cyclooxygenase (Indomethacin, 10−5 M); (c) Ca2+-activated K+ channels (Kca): small conductance (SKca, Apamin, 10−7 M), intermediate conductance (IKca, TRAM34, 10−5 M), and big conductance (BKca, paxilline, 10−5 M); and (d) endothelial-derived hyperpolarizing factor (high KCl, 80 mM). Aspirin caused a concentration-dependent vasodilation. Aspirin-vasodilation was abolished by removal of endothelium or by high KCl. Furthermore, preincubation with either apamin plus TRAM-34 or paxillin significantly attenuated aspirin vasodilation (p < 0.05). For the first time, we showed that aspirin induced endothelium-dependent vasodilation in mesenteric resistance arteries through the endothelial-derived hyperpolarizing factor (EDHF) and calcium-activated potassium channels. By activating this molecular mechanism, aspirin may lower peripheral vascular resistance and be beneficial in pregnancies complicated by hypertension.

scholarly journals Novel role of endothelial BKCa channels in altered vasoreactivity following hypoxia

2010 ◽  
Vol 299 (5) ◽  
pp. H1439-H1450 ◽  
Author(s):  
Jennifer M. Hughes ◽  
Melissa A. Riddle ◽  
Michael L. Paffett ◽  
Laura V. Gonzalez Bosc ◽  
Benjimen R. Walker
Keyword(s):  
Ex Vivo ◽  
Barometric Pressure ◽  
Channel Blockers ◽  
Channel Activity ◽  
Resistance Arteries ◽  
Bkca Channels ◽  
Oxide Synthase ◽  
Increased Activity ◽  
Small Conductance

The systemic vasculature exhibits attenuated vasoconstriction following hypobaric chronic hypoxia (CH) that is associated with endothelium-dependent vascular smooth muscle (VSM) cell hyperpolarization. We hypothesized that increased activity of endothelial cell (EC) large-conductance, calcium-activated potassium (BKCa) channels contributes to this response. Gracilis resistance arteries from hypobaric CH (barometric pressure = 380 mmHg for 48 h) rats demonstrated reduced myogenic reactivity and hyperpolarized VSM membrane potential ( Em) compared with controls under normoxic ex vivo conditions. These differences were eliminated by endothelial disruption. In the presence of cyclooxygenase and nitric oxide synthase inhibition, combined intraluminal administration of the intermediate and small-conductance, calcium-activated K+ channel blockers TRAM-34 and apamin was without effect on myogenic responsiveness and VSM Em in both groups; however, these variables were normalized in CH arteries by intraluminal administration of the BKCa inhibitor iberiotoxin (IBTX). Basal EC Em was hyperpolarized in arteries from CH rats compared with controls and was restored by IBTX, but not by TRAM-34/apamin. K+ channel blockers were without effect on EC basal Em in controls. Similarly, IBTX blocked acetylcholine-induced dilation in arteries from CH rats, but was without effect in controls, whereas TRAM-34/apamin eliminated dilation in controls. Acetylcholine-induced EC hyperpolarization and calcium responses were inhibited by IBTX in CH arteries and by TRAM-34/apamin in controls. Patch-clamp experiments on freshly isolated ECs demonstrated greater K+ current in cells from CH rats that was normalized by IBTX. IBTX was without effect on K+ current in controls. We conclude that hypobaric CH induces increased endothelial BKCa channel activity that contributes to reduced myogenic responsiveness and EC and VSM cell hyperpolarization.

Modulation of vasomotion in resistance arteries of JCR:LA-cp rats: a model of insulin resistance

1999 ◽  
Vol 77 (1) ◽  
pp. 71-74 ◽  
Author(s):  
Sheila F O'Brien ◽  
James C Russell ◽  
Sandra T Davidge
Keyword(s):  
Nitric Oxide ◽  
Insulin Resistance ◽  
Mesenteric Arteries ◽  
Resistance Arteries ◽  
Nitric Oxide Synthase Inhibitor ◽  
Insulin Resistant ◽  
Increased Risk ◽  
Prostaglandin H ◽  
Synthase Inhibitor ◽  
Oxide Synthase

Obesity and insulin resistance are strongly associated with an increased risk of vascular disease. Vasomotion is the cyclic variation in the diameter of arteries and is a general feature of the vasculature that may have important physiological consequences. We tested the hypothesis that obesity - insulin resistance is associated with abnormal vasomotion by comparing obese, insulin-resistant JCR:LA-cp rats, known to develop vasculopathy, atherosclerosis, and ischemic lesions of the heart, with lean insulin-sensitive animals from the same strain. Vasomotion was assessed using isolated mesenteric arteries on a myograph system after preconstriction to 50% of maximal constriction with norepinephrine. The amplitude of vasomotion was enhanced by the presence of meclofenamate, a prostaglandin H synthase inhibitor, and was diminished by NG-nitro-L-arginine methyl ester (L-NAME), a nitric oxide synthase inhibitor. Removal of the endothelium essentially abolished vasomotion, and meclofenamate had no effect on de-endothelialized arteries. Frequency was not altered by either L-NAME or meclofenamate. Although pharmacological inhibition of nitric oxide and eicosanoid production clearly altered vasomotion, there was no difference in the amplitude or frequency of vasomotion in arteries from obese rats compared with lean rats. These results indicate that the endothelium plays a central role in modulating vasomotion, involving both enhancing and inhibiting effects, and that vasomotion is similar between obese, insulin-resistant and lean, insulin-sensitive rats.Key words: insulin resistance, vasomotion, resistance arteries, JCR:LA-cp rats.

Role of CO in attenuated vasoconstrictor reactivity of mesenteric resistance arteries after chronic hypoxia

2002 ◽  
Vol 282 (1) ◽  
pp. H30-H37 ◽  
Author(s):  
Rayna J. Gonzales ◽  
Benjimen R. Walker
Keyword(s):  
Chronic Hypoxia ◽  
Protoporphyrin Ix ◽  
Aortic Ring ◽  
Mesenteric Arteries ◽  
Zinc Protoporphyrin ◽  
Sprague Dawley ◽  
Resistance Arteries ◽  
Sprague Dawley Rats ◽  
Oxide Synthase

Chronic hypoxia (CH) is associated with a persistent reduction in systemic vasoconstrictor reactivity. Experiments on aortic ring segments isolated from CH rats suggest that enhanced vascular expression of heme oxygenase (HO) and resultant production of the vasodilator carbon monoxide (CO) may underlie this attenuated vasoreactivity after hypoxia. Similar to the aorta, small arteries from CH rats exhibit blunted reactivity; however, the regulatory role of CO in the resistance vasculature has not been established. Therefore, we examined the significance of HO activity on responsiveness to phenylephrine (PE) in the mesenteric circulation of control and CH rats. To document that the mesenteric bed demonstrates reduced reactivity after CH, we determined the vasoconstrictor responses of conscious, chronically instrumented male Sprague-Dawley rats to PE under control conditions and then immediately after exposure to 48 h CH (0.5 atm). All rats showed reduced mesenteric vasoconstriction to PE after CH. To examine the role of CO in reduced reactivity, small mesenteric arteries (100–200 μm intraluminal diameter) from control and 48-h CH rats were isolated and mounted on glass cannulas, pressurized to 60 mmHg and superfused with increasing concentrations of PE under normoxic conditions. Similar to the intact circulation, vessels from CH rats exhibited reduced vasoconstrictor sensitivity to PE compared with controls that persisted in the presence of nitric oxide synthase inhibition. The HO inhibitor, zinc protoporphyrin IX (5 μM) enhanced reactivity only in CH vessels. Additionally, a range of concentrations of the HO substrate heme-l-lysinate caused vasodilation in CH vessels but not in controls. Thus we conclude that CO contributes a significant vasodilator influence in resistance vessels after CH that may account for diminished vasoconstrictor responsiveness under these conditions.

scholarly journals Epithelial Na+ channel differentially contributes to shear stress-mediated vascular responsiveness in carotid and mesenteric arteries from mice

2018 ◽  
Vol 314 (5) ◽  
pp. H1022-H1032 ◽  
Author(s):  
Zoe Ashley ◽  
Sama Mugloo ◽  
Fiona J. McDonald ◽  
Martin Fronius
Keyword(s):  
Nitric Oxide ◽  
Shear Stress ◽  
Nitric Oxide Synthase ◽  
Signaling Pathways ◽  
Endothelial Nitric Oxide Synthase ◽  
Mesenteric Arteries ◽  
Intraluminal Pressure ◽  
Resistance Arteries ◽  
Oxide Synthase ◽  
Endothelial Nitric Oxide

A potential “new player” in arteries for mediating shear stress responses is the epithelial Na+ channel (ENaC). The contribution of ENaC as shear sensor in intact arteries, and particularly different types of arteries (conduit and resistance), is unknown. We investigated the role of ENaC in both conduit (carotid) and resistance (third-order mesenteric) arteries isolated from C57Bl/6J mice. Vessel characteristics were determined at baseline (60 mmHg, no flow) and in response to increased intraluminal pressure and shear stress using a pressure myograph. These protocols were performed in the absence and presence of the ENaC inhibitor amiloride (10 µM) and after inhibition of endothelial nitric oxide synthase (eNOS) by Nω-nitro-l-arginine methyl ester (l-NAME; 100 µM). Under no-flow conditions, amiloride increased internal and external diameters of carotid (13 ± 2%, P < 0.05) but not mesenteric (0.5 ± 0.9%, P > 0.05) arteries. In response to increased intraluminal pressure, amiloride had no effect on the internal diameter of either type of artery. However, amiloride affected the stress-strain curves of mesenteric arteries. With increased shear stress, ENaC-dependent effects were observed in both arteries. In carotid arteries, amiloride augmented flow-mediated dilation (9.2 ± 5.3%) compared with control (no amiloride, 6.2 ± 3.3%, P < 0.05). In mesenteric arteries, amiloride induced a flow-mediated constriction (−11.5 ± 6.6%) compared with control (−2.2 ± 4.5%, P < 0.05). l-NAME mimicked the effect of ENaC inhibition and prevented further amiloride effects in both types of arteries. These observations indicate that ENaC contributes to shear sensing in conduit and resistance arteries. ENaC-mediated effects were associated with NO production but may involve different (artery-dependent) downstream signaling pathways. NEW & NOTEWORTHY The epithelial Na+ channel (ENaC) contributes to shear sensing in conduit and resistance arteries. In conduit arteries ENaC has a role as a vasoconstrictor, whereas in resistance arteries ENaC contributes to vasodilation. Interaction of ENaC with endothelial nitric oxide synthase/nitric oxide signaling to mediate the effects is supported; however, cross talk with other shear stress-dependent signaling pathways cannot be excluded. Listen to this article’s corresponding podcast at https://ajpheart.podbean.com/e/different-roles-of-enac-in-carotid-and-mesenteric-arteries/ .

scholarly journals Modulation of Cardiovascular Function in Primary Hypertension in Rat by SKA-31, an Activator of KCa2.x and KCa3.1 Channels

2019 ◽  
Vol 20 (17) ◽  
pp. 4118 ◽  
Author(s):  
Kloza ◽  
Baranowska-Kuczko ◽  
Toczek ◽  
Kusaczuk ◽  
Sadowska ◽  
...  
Keyword(s):  
Mesenteric Arteries ◽  
Spontaneously Hypertensive ◽  
Downstream Signaling ◽  
Calcium Activated Potassium Channels ◽  
Wistar Kyoto ◽  
Oxide Synthase ◽  
Prostacyclin Synthase ◽  
Promising Avenue

The aim of this study was to investigate the hemodynamic effects of SKA-31, an activator of the small (KCa2.x) and intermediate (KCa3.1) conductance calcium-activated potassium channels, and to evaluate its influence on endothelium-derived hyperpolarization (EDH)-KCa2.3/KCa3.1 type relaxation in isolated endothelium-intact small mesenteric arteries (sMAs) from spontaneously hypertensive rats (SHRs). Functional in vivo and in vitro experiments were performed on SHRs or their normotensive controls, Wistar-Kyoto rats (WKY). SKA-31 (1, 3 and 10 mg/kg) caused a brief decrease in blood pressure and bradycardia in both SHR and WKY rats. In phenylephrine-pre-constricted sMAs of SHRs, SKA-31 (0.01–10 µM)-mediated relaxation was reduced and SKA-31 potentiated acetylcholine-evoked endothelium-dependent relaxation. Endothelium denudation and inhibition of nitric oxide synthase (eNOS) and cyclooxygenase (COX) by the respective inhibitors l-NAME or indomethacin, attenuated SKA-31-mediated vasorelaxation. The inhibition of KCa3.1, KCa2.3, KIR and Na+/K+-ATPase by TRAM-34, UCL1684, Ba2+ and ouabain, respectively, reduced the potency and efficacy of the EDH-response evoked by SKA-31. The mRNA expression of eNOS, prostacyclin synthase, KCa2.3, KCa3.1 and KIR were decreased, while Na+/K+-ATPase expression was increased. Collectively, SKA-31 promoted hypotension and vasodilatation, potentiated agonist-stimulated vasodilation, and maintained KCa2.3/KCa3.1-EDH-response in sMAs of SHR with downstream signaling that involved KIR and Na+/K+-ATPase channels. In view of the importance of the dysfunction of endothelium-mediated vasodilatation in the mechanism of hypertension, application of activators of KCa2.3/KCa3.1 channels such as SKA-31 seem to be a promising avenue in pharmacotherapy of hypertension.

scholarly journals Increased superoxide leads to decreased flow-induced dilation in resistance arteries of Mn-SOD-deficient mice

2005 ◽  
Vol 288 (5) ◽  
pp. H2225-H2231 ◽  
Author(s):  
Changdong Yan ◽  
An Huang ◽  
Zhiping Wu ◽  
Pawel M. Kaminski ◽  
Michael S. Wolin ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Nitric Oxide Synthase ◽  
Vascular Function ◽  
Manganese Superoxide Dismutase ◽  
Mesenteric Arteries ◽  
Resistance Arteries ◽  
Enos Activity ◽  
Oxide Synthase ◽  
Endothelial Nitric Oxide ◽  
Enos Protein

The role of mitochondrial manganese-superoxide dismutase (Mn-SOD) in the maintenance of vascular function has not yet been studied. Thus we examined flow- and agonist-induced dilations in isolated mesenteric arteries (∼90 μm in diameter) of Mn-SOD heterozygous (Mn-SOD+/−) and wild-type (WT) mice. Increases in flow elicited dilations in all vessels, but the magnitude of the dilation was significantly less in vessels of Mn-SOD+/− mice than in those of WT mice (64 vs. 74% of passive diameter). Nω-nitro-l-arginine methyl ester inhibited the dilation in vessels of WT mice but had no effect on vessels of Mn-SOD+/− mice. Tempol or tiron (superoxide scavengers) increased flow-induced dilation in vessels of Mn-SOD+/− mice. Acetylcholine- and sodium nitroprusside-induced, but not adenosine-induced, dilations were also decreased in arteries of Mn-SOD+/− mice. Superoxide levels in the arteries of Mn-SOD+/− mice were significantly increased. Western blot analysis confirmed a 50% reduction of Mn-SOD protein in the vessels of Mn-SOD+/− mice. A 41% reduction in endothelial nitric oxide synthase (eNOS) protein and a 37% reduction in eNOS activity were also found in the vessels of Mn-SOD+/− mice. Whereas there was no difference in eNOS protein in kidney homogenates of WT and Mn-SOD+/− mice, a significant reduction of nitric oxide synthase activity was found in Mn-SOD+/− mice, which could be restored by the administration of tiron. We conclude that an increased concentration of superoxide due to reduced activity of Mn-SOD, which inactivates nitric oxide and inhibits eNOS activity, contributes to the impaired vasodilator function of isolated mesenteric arteries of Mn-SOD+/− mice. These results suggest that Mn-SOD contributes significantly to the regulation of vascular function.

Biosynthetic strategies for tetramic acid formation

2021 ◽  
Author(s):  
Xuhua Mo ◽  
Tobias A. M. Gulder
Keyword(s):  
Molecular Mechanism ◽  
Gene Clusters ◽  
Acid Formation ◽  
Biosynthetic Gene ◽  
Tetramic Acid ◽  
Biosynthetic Gene Clusters ◽  
The Individual ◽  
First Time ◽  
Acid Unit

Over 30 biosynthetic gene clusters for natural tetramate have been identified. This highlight reviews the biosynthetic strategies for formation of tetramic acid unit for the first time, discussing the individual molecular mechanism in detail.

Myogenic reactivity is reduced in small renal arteries isolated from relaxin-treated rats

2002 ◽  
Vol 283 (2) ◽  
pp. R349-R355 ◽  
Author(s):  
Jacqueline Novak ◽  
Rolando J. J. Ramirez ◽  
Robin E. Gandley ◽  
O. David Sherwood ◽  
Kirk P. Conrad
Keyword(s):  
Nitric Oxide ◽  
Virgin Female ◽  
Renal Arteries ◽  
Mesenteric Arteries ◽  
Blood Levels ◽  
Renal Circulation ◽  
Nitric Oxide Synthase Inhibitor ◽  
Myogenic Responses ◽  
Synthase Inhibitor ◽  
Oxide Synthase

Administration of the ovarian hormone relaxin to nonpregnant rats vasodilates the renal circulation comparable to pregnancy. This vasodilation is mediated by endothelin (ET), the ETB receptor, and nitric oxide. Furthermore, endogenous relaxin mediates the renal vasodilation and hyperfiltration that occur during gestation. The goal of this study was to investigate whether myogenic reactivity of small renal and mesenteric arteries is reduced in relaxin-treated rats comparable to the pregnant condition. Relaxin or vehicle was administered to virgin female Long-Evans rats for 5 days at 4 μg/h, thereby producing midgestational blood levels of the hormone. The myogenic responses of small renal arteries (200–300 μm in diameter) isolated from these animals were evaluated in an isobaric arteriograph system. Myogenic reactivity was significantly reduced in the small renal arteries from relaxin-treated compared with vehicle-treated rats. The reduced myogenic responses were mediated by the ETB receptor and nitric oxide since the selective ETB receptor antagonist RES-701–1 and the nitric oxide synthase inhibitor N G-nitro-l-arginine methyl ester restored myogenic reactivity to virgin levels. The influence of relaxin was not limited to the renal circulation because myogenic reactivity was also reduced in small mesenteric arteries isolated from relaxin-treated rats. Thus relaxin administration to nonpregnant rats mimics pregnancy, insofar as myogenic reactivity of small renal and mesenteric arteries is reduced in both conditions.

scholarly journals Down-regulation of the Small Conductance Calcium-activated Potassium Channels in Diabetic Mouse Atria

2015 ◽  
Vol 290 (11) ◽  
pp. 7016-7026 ◽  
Author(s):  
Fu Yi ◽  
Tian-You Ling ◽  
Tong Lu ◽  
Xiao-Li Wang ◽  
Jingchao Li ◽  
...  
Keyword(s):  
Potassium Channels ◽  
Diabetic Mouse ◽  
Down Regulation ◽  
Calcium Activated Potassium Channels ◽  
Small Conductance

Increasing dihydrobiopterin causes dysfunction of endothelial nitric oxide synthase in rats in vivo

2011 ◽  
Vol 301 (3) ◽  
pp. H721-H729 ◽  
Author(s):  
Katsuhiko Noguchi ◽  
Naobumi Hamadate ◽  
Toshihiro Matsuzaki ◽  
Mayuko Sakanashi ◽  
Junko Nakasone ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Nitric Oxide Synthase ◽  
Endothelial Nitric Oxide Synthase ◽  
Control Treatment ◽  
Enos Uncoupling ◽  
Nos Inhibitor ◽  
Oxide Synthase ◽  
Endothelial Nitric Oxide ◽  
First Time

An elevation of oxidized forms of tetrahydrobiopterin (BH4), especially dihydrobiopterin (BH2), has been reported in the setting of oxidative stress, such as arteriosclerotic/atherosclerotic disorders, where endothelial nitric oxide synthase (eNOS) is dysfunctional, but the role of BH2 in the regulation of eNOS activity in vivo remains to be evaluated. This study was designed to clarify whether increasing BH2 concentration causes endothelial dysfunction in rats. To increase vascular BH2 levels, the BH2 precursor sepiapterin (SEP) was intravenously given after the administration of the specific dihydrofolate reductase inhibitor methotrexate (MTX) to block intracellular conversion of BH2 to BH4. MTX/SEP treatment did not significantly affect aortic BH4 levels compared with control treatment. However, MTX/SEP treatment markedly augmented aortic BH2 levels (291.1 ± 29.2 vs. 33.4 ± 6.4 pmol/g, P < 0.01) in association with moderate hypertension. Treatment with MTX alone did not significantly alter blood pressure or BH4 levels but decreased the BH4-to-BH2 ratio. Treatment with MTX/SEP, but not with MTX alone, impaired ACh-induced vasodilator and depressor responses compared with the control treatment (both P < 0.05) and also aggravated ACh-induced endothelium-dependent relaxations ( P < 0.05) of isolated aortas without affecting sodium nitroprusside-induced endothelium-independent relaxations. Importantly, MTX/SEP treatment significantly enhanced aortic superoxide production, which was diminished by NOS inhibitor treatment, and the impaired ACh-induced relaxations were reversed with SOD ( P < 0.05), suggesting the involvement of eNOS uncoupling. These results indicate, for the first time, that increasing BH2 causes eNOS dysfunction in vivo even in the absence of BH4 deficiency, demonstrating a novel insight into the regulation of endothelial function.

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