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1.
J Physiol ; 601(3): 469-481, 2023 02.
Artigo em Inglês | MEDLINE | ID: mdl-36575638

RESUMO

Microvascular dysfunction predicts adverse cardiovascular events despite absence of large vessel disease. A shift in the mediator of flow-mediated dilatation (FMD) from nitric oxide (NO) to mitochondrial-derived hydrogen peroxide (H2 O2 ) occurs in arterioles from patients with coronary artery disease (CAD). The underlying mechanisms governing this shift are not completely defined. Lipid phosphate phosphatase 3 (LPP3) is a transmembrane protein that dephosphorylates lysophosphatidic acid, a bioactive lipid, causing a receptor-mediated increase in reactive oxygen species. A single nucleotide loss-of-function polymorphism in the gene coding for LPP3 (rs17114036) is associated with elevated risk for CAD, independent of traditional risk factors. LPP3 is suppressed by miR-92a, which is elevated in the circulation of patients with CAD. Repression of LPP3 increases vascular inflammation and atherosclerosis in animal models. We investigated the role of LPP3 and miR-92a as a mechanism for microvascular dysfunction in CAD. We hypothesized that modulation of LPP3 is critically involved in the disease-associated shift in mediator of FMD. LPP3 protein expression was reduced in left ventricle tissue from CAD relative to non-CAD patients (P = 0.004), with mRNA expression unchanged (P = 0.96). Reducing LPP3 expression (non-CAD) caused a shift from NO to H2 O2 (% maximal dilatation: Control 78.1 ± 11.4% vs. Peg-Cat 30.0 ± 11.2%; P < 0.0001). miR-92a is elevated in CAD arterioles (fold change: 1.9 ± 0.01 P = 0.04), while inhibition of miR-92a restored NO-mediated FMD (CAD), and enhancing miR-92a expression (non-CAD) elicited H2 O2 -mediated dilatation (P < 0.0001). Our data suggests LPP3 is crucial in the disease-associated switch in the mediator of FMD. KEY POINTS: Lipid phosphate phosphatase 3 (LPP3) expression is reduced in heart tissue patients with coronary artery disease (CAD). Loss of LPP3 in CAD is associated with an increase in the LPP3 inhibitor, miR-92a. Inhibition of LPP3 in the microvasculature of healthy patients mimics the CAD flow-mediated dilatation (FMD) phenotype. Inhibition of miR-92a restores nitric oxide-mediated FMD in the microvasculature of CAD patients.


Assuntos
Doença da Artéria Coronariana , MicroRNAs , Animais , Humanos , Óxido Nítrico , Arteríolas/metabolismo , Doença da Artéria Coronariana/genética , Dilatação , Células Cultivadas , MicroRNAs/genética , MicroRNAs/metabolismo , Vasodilatação/fisiologia
2.
BMC Anesthesiol ; 22(1): 240, 2022 07 29.
Artigo em Inglês | MEDLINE | ID: mdl-35906533

RESUMO

BACKGROUND: Hypotension that is resistant to phenylephrine is a complication that occurs in anesthetized patients treated with angiotensin converting enzyme (ACE) inhibitors. We tested the hypothesis that Ang 1-7 and the endothelial Mas receptor contribute to vasodilation produced by propofol in the presence of captopril. METHODS: The internal diameters of human adipose resistance arterioles were measured before and after administration of phenylephrine (10-9 to 10-5 M) in the presence and absence of propofol (10-6 M; added 10 min before the phenylephrine) or the Mas receptor antagonist A779 (10-5 M; added 30 min before phenylephrine) in separate experimental groups. Additional groups of arterioles were incubated for 16 to 20 h with captopril (10-2 M) or Ang 1-7 (10-9 M) before experimentation with phenylephrine, propofol, and A779. RESULTS: Propofol blunted phenylephrine-induced vasoconstriction in normal vessels. Captopril pretreatment alone did not affect vasoconstriction, but the addition of propofol markedly attenuated the vasomotor response to phenylephrine. A779 alone did not affect vasoconstriction in normal vessels, but it restored vasoreactivity in arterioles pretreated with captopril and exposed to propofol. Ang 1-7 reduced the vasoconstriction in response to phenylephrine. Addition of propofol to Ang 1-7-pretreated vessels further depressed phenylephrine-induced vasoconstriction to an equivalent degree as the combination of captopril and propofol, but A779 partially reversed this effect. CONCLUSIONS: Mas receptor activation by Ang 1-7 contributes to phenylephrine-resistant vasodilation in resistance arterioles pretreated with captopril and exposed to propofol. These data suggest an alternative mechanism by which refractory hypotension may occur in anesthetized patients treated with ACE inhibitors.


Assuntos
Hipotensão , Propofol , Angiotensina II/farmacologia , Inibidores da Enzima Conversora de Angiotensina/farmacologia , Arteríolas/fisiologia , Captopril/farmacologia , Humanos , Fenilefrina/farmacologia , Propofol/farmacologia
3.
Arterioscler Thromb Vasc Biol ; 41(1): 446-457, 2021 01.
Artigo em Inglês | MEDLINE | ID: mdl-33232201

RESUMO

OBJECTIVE: Coronary artery disease (CAD) is associated with a compensatory switch in mechanism of flow-mediated dilation (FMD) from nitric oxide (NO) to H2O2. The underlying mechanism responsible for the pathological shift is not well understood, and recent reports directly implicate telomerase and indirectly support a role for autophagy. We hypothesize that autophagy is critical for shear stress-induced release of NO and is a crucial component of for the pathway by which telomerase regulates FMD. Approach and Results: Human left ventricular, atrial, and adipose resistance arterioles were collected for videomicroscopy and immunoblotting. FMD and autophagic flux were measured in arterioles treated with autophagy modulators alone, and in tandem with telomerase-activity modulators. LC3B II/I was higher in left ventricular tissue from patients with CAD compared with non-CAD (2.8±0.2 versus 1.0±0.2-fold change; P<0.05), although p62 was similar between groups. Shear stress increased Lysotracker fluorescence in non-CAD arterioles, with no effect in CAD arterioles. Inhibition of autophagy in non-CAD arterioles induced a switch from NO to H2O2, while activation of autophagy restored NO-mediated vasodilation in CAD arterioles. In the presence of an autophagy activator, telomerase inhibitor prevented the expected switch (Control: 82±4%; NG-Nitro-l-arginine methyl ester: 36±5%; polyethylene glycol catalase: 80±3). Telomerase activation was unable to restore NO-mediated FMD in the presence of autophagy inhibition in CAD arterioles (control: 72±7%; NG-Nitro-l-arginine methyl ester: 79±7%; polyethylene glycol catalase: 38±9%). CONCLUSIONS: We provide novel evidence that autophagy is responsible for the pathological switch in dilator mechanism in CAD arterioles, demonstrating that autophagy acts downstream of telomerase as a common denominator in determining the mechanism of FMD.


Assuntos
Tecido Adiposo/irrigação sanguínea , Arteríolas/enzimologia , Autofagia , Doença da Artéria Coronariana/enzimologia , Vasos Coronários/enzimologia , Telomerase/metabolismo , Vasodilatação , Adulto , Idoso , Arteríolas/patologia , Arteríolas/fisiopatologia , Estudos de Casos e Controles , Doença da Artéria Coronariana/patologia , Doença da Artéria Coronariana/fisiopatologia , Vasos Coronários/patologia , Vasos Coronários/fisiopatologia , Feminino , Humanos , Peróxido de Hidrogênio/metabolismo , Lisossomos/enzimologia , Lisossomos/patologia , Masculino , Proteínas Associadas aos Microtúbulos/metabolismo , Pessoa de Meia-Idade , Óxido Nítrico/metabolismo , Transdução de Sinais
4.
J Am Heart Assoc ; 8(17): e013153, 2019 09 03.
Artigo em Inglês | MEDLINE | ID: mdl-31462128

RESUMO

Background Elevated levels of ceramide, a sphingolipid known to cause a transition from nitric oxide (NO)- to hydrogen peroxide-dependent flow-induced dilation (FID) in human arterioles, correlate with adverse cardiac events. However, elevations of ceramide are associated with changed concentrations of other sphingolipid metabolites. The effects of sphingolipid metabolites generated through manipulation of this lipid pathway on microvascular function are unknown. We examined the hypothesis that inhibition or activation of the ceramide pathway would determine the mediator of FID. Methods and Results Using videomicroscopy, internal diameter changes were measured in human arterioles collected from discarded adipose tissue during surgery. Inhibition of neutral ceramidase, an enzyme responsible for the hydrolysis of ceramide, favored hydrogen peroxide-dependent FID in arterioles from healthy patients. Using adenoviral technology, overexpression of neutral ceramidase in microvessels from diseased patients resulted in restoration of NO-dependent FID. Exogenous sphingosine-1-phosphate, a sphingolipid with opposing effects of ceramide, also restored NO as the mediator of FID in diseased arterioles. Likewise, exogenous adiponectin, a known activator of neutral ceramidase, or, activation of adiponectin receptors, favored NO-dependent dilation in arterioles collected from patients with coronary artery disease. Conclusions Sphingolipid metabolites play a critical role in determining the mediator of FID in human resistance arterioles. Manipulating the sphingolipid balance towards ceramide versus sphingosine-1-phosphate favors microvascular dysfunction versus restoration of NO-mediated FID, respectively. Multiple targets exist within this biolipid pathway to treat microvascular dysfunction and potentially improve patient outcomes.


Assuntos
Tecido Adiposo/irrigação sanguínea , Arteríolas/metabolismo , Ceramidas/metabolismo , Doença da Artéria Coronariana/metabolismo , Vasodilatação , Adiponectina/farmacologia , Adulto , Idoso , Arteríolas/efeitos dos fármacos , Arteríolas/fisiopatologia , Estudos de Casos e Controles , Doença da Artéria Coronariana/fisiopatologia , Inibidores Enzimáticos/farmacologia , Feminino , Humanos , Peróxido de Hidrogênio/metabolismo , Hidrólise , Lisofosfolipídeos/farmacologia , Masculino , Pessoa de Meia-Idade , Ceramidase Neutra/antagonistas & inibidores , Ceramidase Neutra/genética , Ceramidase Neutra/metabolismo , Óxido Nítrico/metabolismo , Transdução de Sinais , Esfingosina/análogos & derivados , Esfingosina/farmacologia , Vasodilatação/efeitos dos fármacos
5.
Br J Pharmacol ; 175(22): 4266-4280, 2018 11.
Artigo em Inglês | MEDLINE | ID: mdl-30153326

RESUMO

BACKGROUND AND PURPOSE: NO produces arteriolar flow-induced dilation (FID) in healthy subjects but is replaced by mitochondria-derived hydrogen peroxide (mtH2 O2 ) in patients with coronary artery disease (CAD). Lysophosphatidic acid (LPA) is elevated in patients with risk factors for CAD, but its functional effect in arterioles is unknown. We tested whether elevated LPA changes the mediator of FID from NO to mtH2 O2 in human visceral and subcutaneous adipose arterioles. EXPERIMENTAL APPROACH: Arterioles were cannulated on glass micropipettes and pressurized to 60 mmHg. We recorded lumen diameter after graded increases in flow in the presence of either NOS inhibition (L-NAME) or H2 O2 scavenging (Peg-Cat) ± LPA (10 µM, 30 min), ±LPA1 /LPA3 receptor antagonist (Ki16425) or LPA2 receptor antagonist (H2L5186303). We analysed LPA receptor RNA and protein levels in human arterioles and human cultured endothelial cells. KEY RESULTS: FID was inhibited by L-NAME but not Peg-Cat in untreated vessels. In vessels treated with LPA, FID was of similar magnitude but inhibited by Peg-Cat while L-NAME had no effect. Rotenone attenuated FID in vessels treated with LPA indicating mitochondria as a source of ROS. RNA transcripts from LPA1 and LPA2 but not LPA3 receptors were detected in arterioles. LPA1 but not LPA3 receptor protein was detected by Western blot. Pretreatment of vessels with an LPA1 /LPA3 , but not LPA2 , receptor antagonist prior to LPA preserved NO-mediated dilation. CONCLUSIONS AND IMPLICATIONS: These findings suggest an LPA1 receptor-dependent pathway by which LPA increases arteriolar release of mtH2 O2 as a mediator of FMD.


Assuntos
Tecido Adiposo/efeitos dos fármacos , Arteríolas/efeitos dos fármacos , Peróxido de Hidrogênio/metabolismo , Lisofosfolipídeos/farmacologia , Receptores de Ácidos Lisofosfatídicos/metabolismo , Tecido Adiposo/metabolismo , Idoso , Arteríolas/metabolismo , Células Cultivadas , Dilatação , Feminino , Humanos , Peróxido de Hidrogênio/análise , Masculino , Pessoa de Meia-Idade , Mitocôndrias/efeitos dos fármacos , Mitocôndrias/metabolismo
6.
Am J Physiol Heart Circ Physiol ; 314(5): H1053-H1060, 2018 05 01.
Artigo em Inglês | MEDLINE | ID: mdl-29351466

RESUMO

A rise in reactive oxygen species (ROS) may contribute to cardiovascular disease by reducing nitric oxide (NO) levels, leading to loss of NO's vasodilator and anti-inflammatory effects. Although primarily studied in larger conduit arteries, excess ROS release and a corresponding loss of NO also occur in smaller resistance arteries of the microcirculation, but the underlying mechanisms and therapeutic targets have not been fully characterized. We examined whether either of the two subunits of telomerase, telomerase reverse transcriptase (TERT) or telomerase RNA component (TERC), affect microvascular ROS production and peak vasodilation at baseline and in response to in vivo administration to angiotensin II (ANG II). We report that genetic loss of TERT [maximal dilation: 52.0 ± 6.1% with vehicle, 60.4 ± 12.9% with Nω-nitro-l-arginine methyl ester (l-NAME), and 32.2 ± 12.2% with polyethylene glycol-catalase (PEG-Cat) ( P < 0.05), means ± SD, n = 9-19] but not TERC [maximal dilation: 79 ± 5% with vehicle, 10.7 ± 9.8% with l-NAME ( P < 0.05), and 86.4 ± 8.4% with PEG-Cat, n = 4-7] promotes flow-induced ROS formation. Moreover, TERT knockout exacerbates the microvascular dysfunction resulting from in vivo ANG II treatment, whereas TERT overexpression is protective [maximal dilation: 88.22 ± 4.6% with vehicle vs. 74.0 ± 7.3% with ANG II (1,000 ng·kg-1·min-1) ( P = not significant), n = 4]. Therefore, loss of TERT but not TERC may be a key contributor to the elevated microvascular ROS levels and reduced peak dilation observed in several cardiovascular disease pathologies. NEW & NOTEWORTHY This study identifies telomerase reverse transcriptase (TERT) but not telomerase RNA component as a key factor regulating endothelium-dependent dilation in the microcirculation. Loss of TERT activity leads to microvascular dysfunction but not conduit vessel dysfunction in first-generation mice. In contrast, TERT is protective in the microcirculation in the presence of prolonged vascular stress. Understanding the mechanism of how TERT protects against vascular stress represents a novel target for the treatment of vascular disorders.


Assuntos
Angiotensina II/toxicidade , Vasos Coronários/efeitos dos fármacos , Endotélio Vascular/efeitos dos fármacos , Artérias Mesentéricas/efeitos dos fármacos , Microvasos/efeitos dos fármacos , Telomerase/metabolismo , Vasodilatação/efeitos dos fármacos , Animais , Vasos Coronários/enzimologia , Vasos Coronários/fisiopatologia , Endotélio Vascular/enzimologia , Endotélio Vascular/fisiopatologia , Feminino , Peróxido de Hidrogênio/metabolismo , Masculino , Artérias Mesentéricas/enzimologia , Artérias Mesentéricas/fisiopatologia , Camundongos Endogâmicos C57BL , Camundongos Knockout , Microvasos/enzimologia , Microvasos/fisiopatologia , Óxido Nítrico/metabolismo , RNA/genética , RNA/metabolismo , Telomerase/deficiência , Telomerase/genética
7.
Hypertension ; 70(1): 166-173, 2017 07.
Artigo em Inglês | MEDLINE | ID: mdl-28533333

RESUMO

Blood flow through healthy human vessels releases NO to produce vasodilation, whereas in patients with coronary artery disease (CAD), the mediator of dilation transitions to mitochondria-derived hydrogen peroxide (mtH2O2). Excessive mtH2O2 production contributes to a proatherosclerotic vascular milieu. Loss of PGC-1α (peroxisome proliferator-activated receptor γ coactivator 1α) is implicated in the pathogenesis of CAD. We hypothesized that PGC-1α suppresses mtH2O2 production to reestablish NO-mediated dilation in isolated vessels from patients with CAD. Isolated human adipose arterioles were cannulated, and changes in lumen diameter in response to graded increases in flow were recorded in the presence of PEG (polyethylene glycol)-catalase (H2O2 scavenger) or L-NAME (NG-nitro-l-arginine methyl ester; NOS inhibitor). In contrast to the exclusively NO- or H2O2-mediated dilation seen in either non-CAD or CAD conditions, respectively, flow-mediated dilation in CAD vessels was sensitive to both L-NAME and PEG-catalase after PGC-1α upregulation using ZLN005 and α-lipoic acid. PGC-1α overexpression in CAD vessels protected against the vascular dysfunction induced by an acute increase in intraluminal pressure. In contrast, downregulation of PGC-1α in non-CAD vessels produces a CAD-like phenotype characterized by mtH2O2-mediated dilation (no contribution of NO). Loss of PGC-1α may contribute to the shift toward the mtH2O2-mediated dilation observed in vessels from subjects with CAD. Strategies to boost PGC-1α levels may provide a therapeutic option in patients with CAD by shifting away from mtH2O2-mediated dilation, increasing NO bioavailability, and reducing levels of mtH2O2 Furthermore, increased expression of PGC-1α allows for simultaneous contributions of both NO and H2O2 to flow-mediated dilation.


Assuntos
Doença da Artéria Coronariana , Peróxido de Hidrogênio , Óxido Nítrico/metabolismo , Coativador 1-alfa do Receptor gama Ativado por Proliferador de Peroxissomo , Vasodilatação/fisiologia , Disponibilidade Biológica , Catalase/metabolismo , Doença da Artéria Coronariana/metabolismo , Doença da Artéria Coronariana/fisiopatologia , Vasos Coronários/fisiopatologia , Humanos , Peróxido de Hidrogênio/metabolismo , Peróxido de Hidrogênio/farmacologia , Microcirculação/fisiologia , Modelos Biológicos , Coativador 1-alfa do Receptor gama Ativado por Proliferador de Peroxissomo/metabolismo , Coativador 1-alfa do Receptor gama Ativado por Proliferador de Peroxissomo/farmacologia , Polietilenoglicóis/metabolismo , Estatística como Assunto , Vasodilatadores/metabolismo , Vasodilatadores/farmacologia
8.
Free Radic Biol Med ; 103: 87-94, 2017 02.
Artigo em Inglês | MEDLINE | ID: mdl-28007573

RESUMO

OBJECTIVE: Prominent among the endothelium-derived hyperpolarizing factors (EDHFs) are the Cytochrome P450 (CYP) epoxygenase-derived arachidonic acid metabolites-the epoxyeicosatrienoic acids (EETs), that are known as vasodilators in the microcirculation. Among the EET isomers, 5,6-EET undergoes rapid lactonization in aqueous solution to the more stable 5,6-δ DHTL (5,6-dihydroxytrienoic lactone) isomer. It is unclear whether this metabolic transformation maintains its vasodilator potential and what is the mechanism of action. Thus, the aim of this study was to investigate the capacity of the lactone isomer, 5,6- δ DHTL, to induce dilation of arterioles and explore the endothelial Ca2+ response mechanism. APPROACH AND RESULTS: In isolated human microvessels 5,6- δ DHTL induced a dose dependent vasodilation, that was inhibited by mechanical denudation of the endothelial layer. This 5,6- δ DHTL -dependent dilation was partially reduced in the presence of L-NAME (NOS inhibitor) or the NO-scavenger, cPTIO (by 19.7%, which was not statistically significantly). In human endothelial cells, 5,6- δ DHTL induced an increase in intracellular Ca2+([Ca2+]i) in a dose dependent manner. This increase in [Ca2+]i was similar to that induced by the 5,6-EET isomer, and significantly higher than observed by administering the hydrolytic dihydroxy isomer, 5,6-DHET. Further experiments aimed to investigate the mechanism of action revealed, that the 5,6-δ DHTL-mediated ([Ca2+]i elevation was reduced by IP3 and ryanodine antagonists, but not by antagonists to the TRPV4 membrane channel. Similar to their effect on the dilation response in the arteries, NO inhibitors reduced the 5,6-δ DHTL-mediated ([Ca2+]i elevation by 20%. Subsequent 5,6-δ DHTL -dependent K+ ion efflux from endothelial cells, was abolished by the inhibition of small and intermediate conductance KCa. CONCLUSIONS: The present study shows that 5,6-δ DHTL is a potential EDHF, that dilates microvessels through a mechanism that involves endothelial dependent Ca2+ entry, requiring endothelial hyperpolarization. These results suggest the existence of additional lactone-containing metabolites that can be derived from the PUFA metabolism and which may function as novel EDHFs.


Assuntos
Endotélio Vascular/efeitos dos fármacos , Ácidos Hidroxieicosatetraenoicos/farmacologia , Vasodilatadores/farmacologia , Arteríolas/efeitos dos fármacos , Sinalização do Cálcio/efeitos dos fármacos , Células Cultivadas , Avaliação Pré-Clínica de Medicamentos , Células Endoteliais/efeitos dos fármacos , Endotélio Vascular/fisiologia , Ativação Enzimática , Humanos , Potenciais da Membrana/efeitos dos fármacos , Óxido Nítrico Sintase Tipo III/metabolismo , Vasodilatação
9.
Circ Res ; 118(5): 856-66, 2016 Mar 04.
Artigo em Inglês | MEDLINE | ID: mdl-26699654

RESUMO

RATIONALE: Telomerase is a nuclear regulator of telomere elongation with recent reports suggesting a role in regulation of mitochondrial reactive oxygen species. Flow-mediated dilation in patients with cardiovascular disease is dependent on the formation of reactive oxygen species. OBJECTIVE: We examined the hypothesis that telomerase activity modulates microvascular flow-mediated dilation, and loss of telomerase activity contributes to the change of mediator from nitric oxide to mitochondrial hydrogen peroxide in patients with coronary artery disease (CAD). METHODS AND RESULTS: Human coronary and adipose arterioles were isolated for videomicroscopy. Flow-mediated dilation was measured in vessels pretreated with the telomerase inhibitor BIBR-1532 or vehicle. Statistical differences between groups were determined using a 2-way analysis of variance repeated measure (n≥4; P<0.05). L-NAME (N(ω)-nitro-L-arginine methyl ester; nitric oxide synthase inhibitor) abolished flow-mediated dilation in arterioles from subjects without CAD, whereas polyethylene glycol-catalase (PEG-catalase; hydrogen peroxide scavenger) had no effect. After exposure to BIBR-1532, arterioles from non-CAD subjects maintained the magnitude of dilation but changed the mediator from nitric oxide to mitochondrial hydrogen peroxide (% max diameter at 100 cm H2O: vehicle 74.6±4.1, L-NAME 37.0±2.0*, PEG-catalase 82.1±2.8; BIBR-1532 69.9±4.0, L-NAME 84.7±2.2, PEG-catalase 36.5±6.9*). Conversely, treatment of microvessels from CAD patients with the telomerase activator AGS 499 converted the PEG-catalase-inhibitable dilation to one mediated by nitric oxide (% max diameter at 100 cm H2O: adipose, AGS 499 78.5±3.9; L-NAME 10.9±17.5*; PEG-catalase 79.2±4.9). Endothelial-independent dilation was not altered with either treatment. CONCLUSIONS: We have identified a novel role for telomerase in re-establishing a physiological mechanism of vasodilation in arterioles from subjects with CAD. These findings suggest a new target for reducing the oxidative milieu in the microvasculature of patients with CAD.


Assuntos
Velocidade do Fluxo Sanguíneo/fisiologia , Vasos Coronários/enzimologia , Microcirculação/fisiologia , Telomerase/fisiologia , Vasodilatação/fisiologia , Tecido Adiposo/irrigação sanguínea , Tecido Adiposo/enzimologia , Idoso , Arteríolas/enzimologia , Células Cultivadas , Doença da Artéria Coronariana/enzimologia , Doença da Artéria Coronariana/patologia , Endotélio Vascular/enzimologia , Feminino , Células Endoteliais da Veia Umbilical Humana/enzimologia , Humanos , Masculino , Pessoa de Meia-Idade
10.
Am J Physiol Heart Circ Physiol ; 307(11): H1587-93, 2014 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-25260615

RESUMO

Endothelial nitric oxide (NO) is the primary mediator of flow-mediated dilation (FMD) in human adipose microvessels. Impaired NO-mediated vasodilation occurs after acute and chronic hypertension, possibly due to excess generation of reactive oxygen species (ROS). The direct role of pressure elevation in this impairment of human arteriolar dilation is not known. We tested the hypothesis that elevation in pressure is sufficient to impair FMD. Arterioles were isolated from human adipose tissue and cannulated, and vasodilation to graded flow gradients was measured before and after exposure to increased intraluminal pressure (IILP; 150 mmHg, 30 min). The mediator of FMD was determined using pharmacological agents to reduce NO [N(G)-nitro-l-arginine methyl ester (l-NAME), 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (c-PTIO)], or H2O2 [polyethylene glycol (PEG)-catalase], and mitochondrial (mt) ROS was quantified using fluorescence microscopy. Exposure to IILP decreased overall FMD (max %dilation: 82.7 ± 4.9 vs. 62 ± 5.6; P < 0.05). This dilation was abolished by treatment with l-NAME prepressure and PEG-catalase after IILP (max %dilation: l-NAME: 23.8 ± 6.1 vs. 74.8 ± 8.6; PEG-catalase: 71.8 ± 5.9 vs. 24.6 ± 10.6). To examine if this change was mediated by mtROS, FMD responses were measured in the presence of the complex I inhibitor rotenone or the mitochondrial antioxidant mitoTempol. Before IILP, FMD was unaffected by either compound; however, both inhibited dilation after IILP. The fluorescence intensity of mitochondria peroxy yellow 1 (MitoPY1), a mitochondria-specific fluorescent probe for H2O2, increased during flow after IILP (%change from static: 12.3 ± 14.5 vs. 127.9 ± 57.7). These results demonstrate a novel compensatory dilator mechanism in humans that is triggered by IILP, inducing a change in the mediator of FMD from NO to mitochondria-derived H2O2.


Assuntos
Arteríolas/fisiologia , Pressão Sanguínea/fisiologia , Peróxido de Hidrogênio , Óxido Nítrico/fisiologia , Vasodilatação/fisiologia , Arteríolas/efeitos dos fármacos , Feminino , Humanos , Técnicas In Vitro , Masculino , Pessoa de Meia-Idade , Mitocôndrias Cardíacas/metabolismo , Pterinas/farmacologia , Espécies Reativas de Oxigênio/metabolismo , Superóxidos/metabolismo , Vasodilatação/efeitos dos fármacos
11.
Circ Res ; 115(5): 525-32, 2014 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-24920698

RESUMO

RATIONALE: Mitochondrial-derived hydrogen peroxide (H2O2) regulates flow-induced dilation (FID) in microvessels from patients with coronary artery disease. The relationship between ceramide, an independent risk factor for coronary artery disease and a known inducer of mitochondrial reactive oxygen species, and FID is unknown. OBJECTIVE: We examined the hypothesis that exogenous ceramide induces a switch in the mediator of FID from nitric oxide to H2O2. METHODS AND RESULTS: Internal diameter changes of resistance arterioles from human adipose and atrial tissue were measured by video microscopy. Mitochondrial H2O2 production was assayed in arterioles using mito peroxy yellow 1. Polyethylene glycol-catalase, rotenone, and Mito-TEMPO impaired FID in healthy adipose arterioles pretreated with ceramide, whereas N(ω)-nitro-l-arginine methyl ester had no effect. Mitochondrial H2O2 production was induced in response to flow in healthy adipose vessels pretreated with ceramide, and this was abolished in the presence of polyethylene glycol-catalase. Immunohistochemistry demonstrated ceramide accumulation in arterioles from both healthy patients and patients with coronary artery disease. N(ω)-nitro-l-arginine methyl ester reduced vasodilation to flow in adipose as well as atrial vessels from patients with coronary artery disease incubated with GW4869, a neutral sphingomyelinase inhibitor, whereas polyethylene glycol-catalase had no effect. CONCLUSIONS: Our data indicate that ceramide has an integral role in the transition of the mediator of FID from nitric oxide to mitochondrial-derived H2O2 and that inhibition of ceramide production can revert the mechanism of dilation back to nitric oxide. Ceramide may be an important target for preventing and treating vascular dysfunction associated with atherosclerosis.


Assuntos
Tecido Adiposo/irrigação sanguínea , Doença da Artéria Coronariana/metabolismo , Circulação Coronária/efeitos dos fármacos , Vasos Coronários/efeitos dos fármacos , Peróxido de Hidrogênio/metabolismo , Microcirculação/efeitos dos fármacos , Óxido Nítrico/metabolismo , Esfingosina/análogos & derivados , Vasodilatação/efeitos dos fármacos , Adulto , Idoso , Antioxidantes/farmacologia , Arteríolas/efeitos dos fármacos , Arteríolas/metabolismo , Arteríolas/fisiopatologia , Estudos de Casos e Controles , Doença da Artéria Coronariana/fisiopatologia , Vasos Coronários/metabolismo , Vasos Coronários/fisiopatologia , Inibidores Enzimáticos/metabolismo , Feminino , Humanos , Masculino , Microscopia de Vídeo , Pessoa de Meia-Idade , Mitocôndrias/efeitos dos fármacos , Mitocôndrias/metabolismo , Óxido Nítrico Sintase/antagonistas & inibidores , Óxido Nítrico Sintase/metabolismo , Fluxo Sanguíneo Regional , Transdução de Sinais/efeitos dos fármacos , Esfingomielina Fosfodiesterase/antagonistas & inibidores , Esfingomielina Fosfodiesterase/metabolismo , Esfingosina/farmacologia , Fatores de Tempo
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