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Barra W, Queiroz B, Perez A, Romero T, Ferreira R, Duarte I. Study on peripheral antinociception induced by hydrogen peroxide (H 2O 2): characterization and mechanisms. NAUNYN-SCHMIEDEBERG'S ARCHIVES OF PHARMACOLOGY 2024; 397:7927-7938. [PMID: 38753048 DOI: 10.1007/s00210-024-03087-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/01/2023] [Accepted: 04/05/2024] [Indexed: 10/04/2024]
Abstract
The present study aimed to evaluate the possible peripheral H2O2-induced antinociception and determine the involvement of opioidergic, cannabinoidergic and nitrergic systems, besides potassium channels in its antinociceptive effect. Prostaglandin E2 was used to induce hyperalgesia in male Swiss mice using the mechanical paw pressure test. H2O2 (0.1, 0.2, 0.3 µg/paw) promoted a dose-dependent antinociceptive effect that was not observed in contralateral paw. Female mice also showed antinociception in the model. The partial H2O2-induced antinociception was potentiated by the inhibitor of catalase enzyme, aminotriazole (40, 60, 80 µg/paw). The antinociception was not reversed by opioid and cannabinoid receptor antagonists naloxone, AM 251 and AM 630. The involvement of nitric oxide (NO) was observed by the reversal of H2O2-induced antinociception using the non-selective inhibitor of nitric oxide synthases L-NOarg and by inhibition of iNOS (L-NIL), eNOS (L-NIO) and nNOS (L-NPA). ODQ, a cGMP-forming enzyme selective inhibitor, also reversed the antinociception. The blockers of potassium channels voltage-gated (TEA), ATP-sensitive (glibenclamide), large (paxillin) and small (dequalinium) conductance calcium-activated were able to revert H2O2 antinociception. Our data suggest that H2O2 induced a peripheral antinociception in mice and the NO pathway and potassium channels (voltage-gated, ATP-sensitive, calcium-activated) are involved in this mechanism. However, the role of the opioid and cannabinoid systems was not evidenced.
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Affiliation(s)
- Walace Barra
- Laboratory of Pain and Analgesia, Department of Pharmacology, Institute of Biological Sciences, Federal University of Minas Gerais, City Belo Horizonte, Brazil
| | - Bárbara Queiroz
- Laboratory of Pain and Analgesia, Department of Pharmacology, Institute of Biological Sciences, Federal University of Minas Gerais, City Belo Horizonte, Brazil
| | - Andrea Perez
- Laboratory of Pain and Analgesia, Department of Pharmacology, Institute of Biological Sciences, Federal University of Minas Gerais, City Belo Horizonte, Brazil
| | - Thiago Romero
- Laboratory of Pain and Analgesia, Department of Pharmacology, Institute of Biological Sciences, Federal University of Minas Gerais, City Belo Horizonte, Brazil
| | - Renata Ferreira
- Laboratory of Pain and Analgesia, Department of Pharmacology, Institute of Biological Sciences, Federal University of Minas Gerais, City Belo Horizonte, Brazil
| | - Igor Duarte
- Laboratory of Pain and Analgesia, Department of Pharmacology, Institute of Biological Sciences, Federal University of Minas Gerais, City Belo Horizonte, Brazil.
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2
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Raph SM, Dwenger MM, Hu X, Nystoriak MA. Basal NAD(H) redox state permits hydrogen peroxide-induced mesenteric artery dilatation. J Physiol 2023; 601:2621-2634. [PMID: 37114864 DOI: 10.1113/jp284195] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2022] [Accepted: 04/26/2023] [Indexed: 04/29/2023] Open
Abstract
Smooth muscle voltage-gated K+ (Kv) channels in resistance arteries control vascular tone and contribute to the coupling of blood flow with local metabolic activity. Members of the Kv1 family are expressed in vascular smooth muscle and are modulated upon physiological elevation of local metabolites, including the glycolytic end-product l-lactate and superoxide-derived hydrogen peroxide (H2 O2 ). Here, we show that l-lactate elicits vasodilatation of small-diameter mesenteric arteries in a mechanism that requires lactate dehydrogenase (LDH). Using the inside-out configuration of the patch clamp technique, we show that increases in NADH that reflect LDH-mediated conversion of l-lactate to pyruvate directly stimulate the activity of single Kv1 channels and significantly enhance the sensitivity of Kv1 activity to H2 O2 . Consistent with these findings, H2 O2 -evoked vasodilatation was significantly greater in the presence of 10 mM l-lactate relative to lactate-free conditions, yet was abolished in the presence of 10 mM pyruvate, which shifts the LDH reaction towards the generation of NAD+ . Moreover, the enhancement of H2 O2 -induced vasodilatation was abolished in arteries from double transgenic mice with selective overexpression of the intracellular Kvβ1.1 subunit in smooth muscle cells. Together, our results indicate that the Kvβ complex of native vascular Kv1 channels serves as a nodal effector for multiple redox signals to precisely control channel activity and vascular tone in the face of dynamic tissue-derived metabolic cues. KEY POINTS: Vasodilatation of mesenteric arteries by elevated external l-lactate requires its conversion by lactate dehydrogenase. Application of either NADH or H2 O2 potentiates single Kv channel currents in excised membrane patches from mesenteric artery smooth muscle cells. The binding of NADH enhances the stimulatory effects of H2 O2 on single Kv channel activity. The vasodilatory response to H2 O2 is differentially modified upon elevation of external l-lactate or pyruvate. The presence of l-lactate enhances the vasodilatory response to H2 O2 via the Kvβ subunit complex in smooth muscle.
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Affiliation(s)
- Sean M Raph
- Department of Pharmacology and Toxicology, University of Louisville, Louisville, KY, USA
| | - Marc M Dwenger
- Department of Pharmacology and Toxicology, University of Louisville, Louisville, KY, USA
| | - Xuemei Hu
- Department of Pharmacology and Toxicology, University of Louisville, Louisville, KY, USA
| | - Matthew A Nystoriak
- Department of Medicine, Division of Environmental Medicine, University of Louisville, Louisville, KY, USA
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3
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Pecchiari M, Pontikis K, Alevrakis E, Vasileiadis I, Kompoti M, Koutsoukou A. Cardiovascular Responses During Sepsis. Compr Physiol 2021; 11:1605-1652. [PMID: 33792902 DOI: 10.1002/cphy.c190044] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Sepsis is the life-threatening organ dysfunction arising from a dysregulated host response to infection. Although the specific mechanisms leading to organ dysfunction are still debated, impaired tissue oxygenation appears to play a major role, and concomitant hemodynamic alterations are invariably present. The hemodynamic phenotype of affected individuals is highly variable for reasons that have been partially elucidated. Indeed, each patient's circulatory condition is shaped by the complex interplay between the medical history, the volemic status, the interval from disease onset, the pathogen, the site of infection, and the attempted resuscitation. Moreover, the same hemodynamic pattern can be generated by different combinations of various pathophysiological processes, so the presence of a given hemodynamic pattern cannot be directly related to a unique cluster of alterations. Research based on endotoxin administration to healthy volunteers and animal models compensate, to an extent, for the scarcity of clinical studies on the evolution of sepsis hemodynamics. Their results, however, cannot be directly extrapolated to the clinical setting, due to fundamental differences between the septic patient, the healthy volunteer, and the experimental model. Numerous microcirculatory derangements might exist in the septic host, even in the presence of a preserved macrocirculation. This dissociation between the macro- and the microcirculation might account for the limited success of therapeutic interventions targeting typical hemodynamic parameters, such as arterial and cardiac filling pressures, and cardiac output. Finally, physiological studies point to an early contribution of cardiac dysfunction to the septic phenotype, however, our defective diagnostic tools preclude its clinical recognition. © 2021 American Physiological Society. Compr Physiol 11:1605-1652, 2021.
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Affiliation(s)
- Matteo Pecchiari
- Dipartimento di Fisiopatologia Medico Chirurgica e dei Trapianti, Università degli Studi di Milano, Milan, Italy
| | - Konstantinos Pontikis
- Intensive Care Unit, 1st Department of Pulmonary Medicine, National & Kapodistrian University of Athens, General Hospital for Diseases of the Chest 'I Sotiria', Athens, Greece
| | - Emmanouil Alevrakis
- 4th Department of Pulmonary Medicine, General Hospital for Diseases of the Chest 'I Sotiria', Athens, Greece
| | - Ioannis Vasileiadis
- Intensive Care Unit, 1st Department of Pulmonary Medicine, National & Kapodistrian University of Athens, General Hospital for Diseases of the Chest 'I Sotiria', Athens, Greece
| | - Maria Kompoti
- Intensive Care Unit, Thriassio General Hospital of Eleusis, Magoula, Greece
| | - Antonia Koutsoukou
- Intensive Care Unit, 1st Department of Pulmonary Medicine, National & Kapodistrian University of Athens, General Hospital for Diseases of the Chest 'I Sotiria', Athens, Greece
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4
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Coburn RF. Coronary and cerebral metabolism-blood flow coupling and pulmonary alveolar ventilation-blood flow coupling may be disabled during acute carbon monoxide poisoning. J Appl Physiol (1985) 2020; 129:1039-1050. [PMID: 32853110 DOI: 10.1152/japplphysiol.00172.2020] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Current evidence indicates that the toxicity of carbon monoxide (CO) poisoning results from increases in reactive oxygen species (ROS) generation plus tissue hypoxia resulting from decreases in capillary Po2 evoked by effects of increases in blood [carboxyhemoglobin] on the oxyhemoglobin dissociation curve. There has not been consideration of how increases in Pco could influence metabolism-blood flow coupling, a physiological mechanism that regulates the uniformity of tissue Po2, and alveolar ventilation-blood flow coupling, a mechanism that increases the efficiency of pulmonary O2 uptake. Using published data, I consider hypotheses that these coupling mechanisms, triggered by O2 and CO sensors located in arterial and arteriolar vessels in the coronary and cerebral circulations and in lung intralobar arteries, are disrupted during acute CO poisoning. These hypotheses are supported by calculations that show that the Pco in these vessels can reach levels during CO poisoning that would exert effects on signal transduction molecules involved in these coupling mechanisms.NEW & NOTEWORTHY This article introduces and supports a postulate that the tissue hypoxia component of carbon monoxide poisoning results in part from impairment of physiological adaptation mechanisms whereby tissues can match regional blood flow to O2 uptake, and the lung can match regional blood flow to alveolar ventilation.
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Affiliation(s)
- Ronald F Coburn
- Department of Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
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5
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Mughal A, Anto S, Sun C, O'Rourke ST. Apelin inhibits an endothelium-derived hyperpolarizing factor-like pathway in rat cerebral arteries. Peptides 2020; 132:170350. [PMID: 32579899 PMCID: PMC7484084 DOI: 10.1016/j.peptides.2020.170350] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/28/2020] [Revised: 06/15/2020] [Accepted: 06/18/2020] [Indexed: 12/20/2022]
Abstract
Apelin has complex vasomotor actions inasmuch as the peptide may cause either vasodilation or vasoconstriction depending on the vascular bed and experimental conditions. In cerebral arteries, apelin inhibits endothelium-dependent relaxations mediated by nitric oxide (NO); however, its effects on relaxation to other endothelium-derived substances (e.g. prostacyclin, endothelium-derived hyperpolarizing factors(s) (EDHF)) are unknown. The present study was designed to determine effects of apelin on endothelium-dependent relaxations that are independent of NO in rat cerebral arteries. In arterial rings contracted with 5-HT, A23187 caused endothelium-dependent relaxation that was unaffected by inhibitors of eNOS, guanylyl cyclase or cyclooxygenase, but was attenuated by MS-PPOH, a selective inhibitor of cytochrome P450 catalyzed synthesis of epoxyeicosatrienoic acids (EETs) and by 14,15-EE(Z)E, an EET-receptor antagonist. Apelin inhibited A23187-induced relaxation, as well as relaxations evoked by exogenous 11,12- and 14,15-EET. These effects of apelin were mimicked by the selective BKCa channel blocker, iberiotoxin. The APJ receptor antagonist, F13A abolished the effects of apelin on A23187-induced relaxations. Both 11,12- and 14,15-EET also increased BKCa channel current density in isolated cerebral artery smooth muscle cells, effects that were inhibited in a similar manner by apelin and iberiotoxin. These findings provide evidence that apelin impairs endothelium-dependent relaxation of cerebral arteries by inhibiting an NO-independent pathway (i.e. "EDHF-like") involving activation of smooth muscle cell BKCa channels by endothelium-derived EETs. Inhibition of such pathway may create an environment favoring vasoconstriction in cerebral arteries.
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Affiliation(s)
- Amreen Mughal
- Department of Pharmaceutical Sciences, North Dakota State University, Fargo, ND, 58108-6050, USA
| | - Santo Anto
- Department of Pharmaceutical Sciences, North Dakota State University, Fargo, ND, 58108-6050, USA
| | - Chengwen Sun
- Department of Pharmaceutical Sciences, North Dakota State University, Fargo, ND, 58108-6050, USA
| | - Stephen T O'Rourke
- Department of Pharmaceutical Sciences, North Dakota State University, Fargo, ND, 58108-6050, USA.
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6
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Severino P, D’Amato A, Pucci M, Infusino F, Birtolo LI, Mariani MV, Lavalle C, Maestrini V, Mancone M, Fedele F. Ischemic Heart Disease and Heart Failure: Role of Coronary Ion Channels. Int J Mol Sci 2020; 21:E3167. [PMID: 32365863 PMCID: PMC7246492 DOI: 10.3390/ijms21093167] [Citation(s) in RCA: 75] [Impact Index Per Article: 18.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2020] [Revised: 04/28/2020] [Accepted: 04/28/2020] [Indexed: 01/09/2023] Open
Abstract
Heart failure is a complex syndrome responsible for high rates of death and hospitalization. Ischemic heart disease is one of the most frequent causes of heart failure and it is normally attributed to coronary artery disease, defined by the presence of one or more obstructive plaques, which determine a reduced coronary blood flow, causing myocardial ischemia and consequent heart failure. However, coronary obstruction is only an element of a complex pathophysiological process that leads to myocardial ischemia. In the literature, attention paid to the role of microcirculation, in the pathophysiology of ischemic heart disease and heart failure, is growing. Coronary microvascular dysfunction determines an inability of coronary circulation to satisfy myocardial metabolic demands, due to the imbalance of coronary blood flow regulatory mechanisms, including ion channels, leading to the development of hypoxia, fibrosis and tissue death, which may determine a loss of myocardial function, even beyond the presence of atherosclerotic epicardial plaques. For this reason, ion channels may represent the link among coronary microvascular dysfunction, ischemic heart disease and consequent heart failure.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | - Francesco Fedele
- Department of Clinical, Internal, Anesthesiology and Cardiovascular Sciences, Sapienza University of Rome, Viale del Policlinico, 155-00161 Rome, Italy; (P.S.); (A.D.); (M.P.); (F.I.); (L.I.B.); (M.V.M.); (C.L.); (V.M.); (M.M.)
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7
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Saeed M, Arun MZ, Guzeloglu M, Onursal C, Gokce G, Korkmaz CG, Reel B. Low-dose doxycycline inhibits hydrogen peroxide-induced oxidative stress, MMP-2 up-regulation and contractile dysfunction in human saphenous vein grafts. DRUG DESIGN DEVELOPMENT AND THERAPY 2019; 13:1791-1801. [PMID: 31213768 PMCID: PMC6536710 DOI: 10.2147/dddt.s187842] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/01/2018] [Accepted: 03/26/2019] [Indexed: 12/12/2022]
Abstract
Background: Cardiopulmonary bypass (CPB) applied during coronary artery bypass grafting (CABG), promotes inflammation, generation of reactive oxygen species (ROS) and up-regulation of matrix metalloproteinases (MMPs). All these complications may lead to contractile dysfunction, restenosis and early graft failure, restricting long-term efficacy of bypass grafts. Low-dose doxycycline is a potent MMP inhibitor and ROS scavenger. In this study, we aimed to investigate the effects of doxycycline on ROS generation, MMP regulation and contractile dysfunction induced by H2O2 in human saphenous vein (HSV) grafts. Methods: HSV grafts (n=7) were divided into four groups after removing endothelial layer by mechanical scratching and incubated with 10 µM H2O2 and/or 10 µM doxycycline for 16 hrs. Untreated segments served as control. Concentration-response curves to noradrenaline (NA), potassium chloride (KCl), serotonin (5-HT) and papaverine were performed. Superoxide anion and other ROS levels were determined by using lucigenin- and luminol-enhanced chemiluminescence assays, respectively. Expression/activity of gelatinases (MMP-2/MMP-9) was examined by gelatin zymography. MMP-13 expression was evaluated by immunostaining/immunoscoring. Results: H2O2 incubation increased superoxide anion and other ROS levels. Doxycycline prevented these increments. H2O2 suppressed contractile responses to NA, KCl and 5-HT. Doxycycline ameliorated contractions to NA and KCl but not to 5-HT. H2O2 or doxycycline did not altered relaxation to papaverine. MMP-2 and MMP-13 expression increased with H2O2, but doxycycline inhibited MMP-2 up-regulation/activation. Conclusion: Low-dose doxycycline may have beneficial effects on increased oxidative stress, MMP up-regulation/activation and contractile dysfunction in HSV grafts.
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Affiliation(s)
- Mazen Saeed
- Ege University, Faculty of Pharmacy, Department of Pharmacology, 35100 Bornova, Izmir, Turkey
| | - Mehmet Zuhuri Arun
- Ege University, Faculty of Pharmacy, Department of Clinical Pharmacy, 35100 Bornova, Izmir, Turkey
| | - Mehmet Guzeloglu
- Optimed Hospital, Department of Cardiovascular Surgery, 59500 Corlu, Tekirdag, Turkey
| | - Ceylan Onursal
- Ege University, Faculty of Pharmacy, Department of Pharmacology, 35100 Bornova, Izmir, Turkey
| | - Goksel Gokce
- Ege University, Faculty of Pharmacy, Department of Clinical Pharmacy, 35100 Bornova, Izmir, Turkey
| | - Ceren Gonen Korkmaz
- Ege University, Faculty of Pharmacy, Department of Clinical Pharmacy, 35100 Bornova, Izmir, Turkey
| | - Buket Reel
- Ege University, Faculty of Pharmacy, Department of Clinical Pharmacy, 35100 Bornova, Izmir, Turkey
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8
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Severino P, D'Amato A, Netti L, Pucci M, Infusino F, Maestrini V, Mancone M, Fedele F. Myocardial Ischemia and Diabetes Mellitus: Role of Oxidative Stress in the Connection between Cardiac Metabolism and Coronary Blood Flow. J Diabetes Res 2019; 2019:9489826. [PMID: 31089475 PMCID: PMC6476021 DOI: 10.1155/2019/9489826] [Citation(s) in RCA: 48] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/10/2018] [Revised: 02/23/2019] [Accepted: 03/13/2019] [Indexed: 12/27/2022] Open
Abstract
Ischemic heart disease (IHD) has several risk factors, among which diabetes mellitus represents one of the most important. In diabetic patients, the pathophysiology of myocardial ischemia remains unclear yet: some have atherosclerotic plaque which obstructs coronary blood flow, others show myocardial ischemia due to coronary microvascular dysfunction in the absence of plaques in epicardial vessels. In the cross-talk between myocardial metabolism and coronary blood flow (CBF), ion channels have a main role, and, in diabetic patients, they are involved in the pathophysiology of IHD. The exposition to the different cardiovascular risk factors and the ischemic condition determine an imbalance of the redox state, defined as oxidative stress, which shows itself with oxidant accumulation and antioxidant deficiency. In particular, several products of myocardial metabolism, belonging to oxidative stress, may influence ion channel function, altering their capacity to modulate CBF, in response to myocardial metabolism, and predisposing to myocardial ischemia. For this reason, considering the role of oxidative and ion channels in the pathophysiology of myocardial ischemia, it is allowed to consider new therapeutic perspectives in the treatment of IHD.
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Affiliation(s)
- Paolo Severino
- Department of Cardiovascular, Respiratory, Nephrology, Anesthesiology and Geriatric Sciences, Sapienza University of Rome, 00161 Rome, Italy
| | - Andrea D'Amato
- Department of Cardiovascular, Respiratory, Nephrology, Anesthesiology and Geriatric Sciences, Sapienza University of Rome, 00161 Rome, Italy
| | - Lucrezia Netti
- Department of Cardiovascular, Respiratory, Nephrology, Anesthesiology and Geriatric Sciences, Sapienza University of Rome, 00161 Rome, Italy
| | - Mariateresa Pucci
- Department of Cardiovascular, Respiratory, Nephrology, Anesthesiology and Geriatric Sciences, Sapienza University of Rome, 00161 Rome, Italy
| | - Fabio Infusino
- Department of Cardiovascular, Respiratory, Nephrology, Anesthesiology and Geriatric Sciences, Sapienza University of Rome, 00161 Rome, Italy
| | - Viviana Maestrini
- Department of Cardiovascular, Respiratory, Nephrology, Anesthesiology and Geriatric Sciences, Sapienza University of Rome, 00161 Rome, Italy
| | - Massimo Mancone
- Department of Cardiovascular, Respiratory, Nephrology, Anesthesiology and Geriatric Sciences, Sapienza University of Rome, 00161 Rome, Italy
| | - Francesco Fedele
- Department of Cardiovascular, Respiratory, Nephrology, Anesthesiology and Geriatric Sciences, Sapienza University of Rome, 00161 Rome, Italy
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9
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Effect of Oxidative Stress on the Estrogen-NOS-NO-K Ca Channel Pathway in Uteroplacental Dysfunction: Its Implication in Pregnancy Complications. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2019; 2019:9194269. [PMID: 30881600 PMCID: PMC6387699 DOI: 10.1155/2019/9194269] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/08/2018] [Revised: 12/19/2018] [Accepted: 01/14/2019] [Indexed: 12/27/2022]
Abstract
During pregnancy, the adaptive changes in uterine circulation and the formation of the placenta are essential for the growth of the fetus and the well-being of the mother. The steroid hormone estrogen plays a pivotal role in this adaptive process. An insufficient blood supply to the placenta due to uteroplacental dysfunction has been associated with pregnancy complications including preeclampsia and intrauterine fetal growth restriction (IUGR). Oxidative stress is caused by an imbalance between free radical formation and antioxidant defense. Pregnancy itself presents a mild oxidative stress, which is exaggerated in pregnancy complications. Increasing evidence indicates that oxidative stress plays an important role in the maladaptation of uteroplacental circulation partly by impairing estrogen signaling pathways. This review is aimed at providing both an overview of our current understanding of regulation of the estrogen-NOS-NO-KCa pathway by reactive oxygen species (ROS) in uteroplacental tissues and a link between oxidative stress and uteroplacental dysfunction in pregnancy complications. A better understanding of the mechanisms will facilitate the development of novel and effective therapeutic interventions.
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10
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Srikanth M, Chandrasaharan K, Zhao X, Chayaburakul K, Ong WY, Herr DR. Metabolism of Docosahexaenoic Acid (DHA) Induces Pyroptosis in BV-2 Microglial Cells. Neuromolecular Med 2018; 20:504-514. [PMID: 30232677 DOI: 10.1007/s12017-018-8511-0] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2018] [Accepted: 09/10/2018] [Indexed: 11/28/2022]
Abstract
DHA is one of the most abundant fatty acids in the brain, largely present in stores of membrane phospholipids. It is readily released by the action of phospholipase A2 and is known to induce anti-inflammatory and neurotrophic effects. It is not thought to contribute to proinflammatory processes in the brain. In this study, an immortalized murine microglia cell line (BV-2) was used to evaluate the effect of DHA on neuroinflammatory cells. Pretreatment of BV-2 cells with low concentrations of DHA (30 µM) attenuates lipopolysaccharide-mediated inflammatory cytokine gene expression, consistent with known anti-inflammatory effects. However, higher (but still physiologically relevant) concentrations of DHA (200 µM) induce profound cell swelling and a reduction of viability. This is accompanied by increases in the expressions of inflammatory cytokine and lipoxygenase genes, activation of caspase-1 activity, and release of IL1β, indicating that cells were undergoing a proinflammatory cell death program known as pyroptosis. This process could be attenuated by pharmacological inhibition of 12-lipoxygenase (12-LOX, Alox12e), but not by inhibition of 5-LOX or 15-LOX. Cumulatively, these data demonstrate that DHA has an anti-inflammatory effect on microglial cells, but its metabolism by 12-LOX generates one or more products that activate a proinflammatory cell death program.
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Affiliation(s)
- Malavika Srikanth
- Department of Pharmacology, Yong Loo Lin School of Medicine, National University Health System, National University of Singapore, Singapore, Singapore
| | - Kalashobini Chandrasaharan
- Department of Pharmacology, Yong Loo Lin School of Medicine, National University Health System, National University of Singapore, Singapore, Singapore
| | - Xinyuan Zhao
- Department of Pharmacology, Yong Loo Lin School of Medicine, National University Health System, National University of Singapore, Singapore, Singapore
| | | | - Wei-Yi Ong
- Department of Anatomy, Yong Loo Lin School of Medicine, National University Health System, National University of Singapore, Singapore, Singapore
| | - Deron R Herr
- Department of Pharmacology, Yong Loo Lin School of Medicine, National University Health System, National University of Singapore, Singapore, Singapore. .,Department of Biology, San Diego State University, San Diego, CA, USA.
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11
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Severino P, D'Amato A, Netti L, Pucci M, De Marchis M, Palmirotta R, Volterrani M, Mancone M, Fedele F. Diabetes Mellitus and Ischemic Heart Disease: The Role of Ion Channels. Int J Mol Sci 2018. [PMID: 29534462 PMCID: PMC5877663 DOI: 10.3390/ijms19030802] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Diabetes mellitus is one the strongest risk factors for cardiovascular disease and, in particular, for ischemic heart disease (IHD). The pathophysiology of myocardial ischemia in diabetic patients is complex and not fully understood: some diabetic patients have mainly coronary stenosis obstructing blood flow to the myocardium; others present with coronary microvascular disease with an absence of plaques in the epicardial vessels. Ion channels acting in the cross-talk between the myocardial energy state and coronary blood flow may play a role in the pathophysiology of IHD in diabetic patients. In particular, some genetic variants for ATP-dependent potassium channels seem to be involved in the determinism of IHD.
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Affiliation(s)
- Paolo Severino
- Department of Cardiovascular, Respiratory, Nephrology, Anesthesiology and Geriatric Sciences, Sapienza University of Rome, 00161 Rome, Italy.
| | - Andrea D'Amato
- Department of Cardiovascular, Respiratory, Nephrology, Anesthesiology and Geriatric Sciences, Sapienza University of Rome, 00161 Rome, Italy.
| | - Lucrezia Netti
- Department of Cardiovascular, Respiratory, Nephrology, Anesthesiology and Geriatric Sciences, Sapienza University of Rome, 00161 Rome, Italy.
| | - Mariateresa Pucci
- Department of Cardiovascular, Respiratory, Nephrology, Anesthesiology and Geriatric Sciences, Sapienza University of Rome, 00161 Rome, Italy.
| | - Marialaura De Marchis
- Department of Cardiovascular, Respiratory, Nephrology, Anesthesiology and Geriatric Sciences, Sapienza University of Rome, 00161 Rome, Italy.
| | - Raffaele Palmirotta
- Department of Biomedical Sciences and Clinical Oncology Oncogenomic Research Center, 'Aldo Moro' University of Bari, 70124 Bari, Italy.
| | - Maurizio Volterrani
- Department of Cardiac Rehabilitation, IRCCS San Raffaele, 00163 Rome, Italy.
| | - Massimo Mancone
- Department of Cardiovascular, Respiratory, Nephrology, Anesthesiology and Geriatric Sciences, Sapienza University of Rome, 00161 Rome, Italy.
| | - Francesco Fedele
- Department of Cardiovascular, Respiratory, Nephrology, Anesthesiology and Geriatric Sciences, Sapienza University of Rome, 00161 Rome, Italy.
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12
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Abstract
The heart is uniquely responsible for providing its own blood supply through the coronary circulation. Regulation of coronary blood flow is quite complex and, after over 100 years of dedicated research, is understood to be dictated through multiple mechanisms that include extravascular compressive forces (tissue pressure), coronary perfusion pressure, myogenic, local metabolic, endothelial as well as neural and hormonal influences. While each of these determinants can have profound influence over myocardial perfusion, largely through effects on end-effector ion channels, these mechanisms collectively modulate coronary vascular resistance and act to ensure that the myocardial requirements for oxygen and substrates are adequately provided by the coronary circulation. The purpose of this series of Comprehensive Physiology is to highlight current knowledge regarding the physiologic regulation of coronary blood flow, with emphasis on functional anatomy and the interplay between the physical and biological determinants of myocardial oxygen delivery. © 2017 American Physiological Society. Compr Physiol 7:321-382, 2017.
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Affiliation(s)
- Adam G Goodwill
- Department of Cellular and Integrative Physiology, Indiana University School of Medicine, Indianapolis, IN
| | - Gregory M Dick
- California Medical Innovations Institute, 872 Towne Center Drive, Pomona, CA
| | - Alexander M Kiel
- Department of Cellular and Integrative Physiology, Indiana University School of Medicine, Indianapolis, IN
- Weldon School of Biomedical Engineering, Purdue University, 206 S Martin Jischke Drive, Lafayette, IN
| | - Johnathan D Tune
- Department of Cellular and Integrative Physiology, Indiana University School of Medicine, Indianapolis, IN
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Tykocki NR, Boerman EM, Jackson WF. Smooth Muscle Ion Channels and Regulation of Vascular Tone in Resistance Arteries and Arterioles. Compr Physiol 2017; 7:485-581. [PMID: 28333380 DOI: 10.1002/cphy.c160011] [Citation(s) in RCA: 222] [Impact Index Per Article: 31.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Vascular tone of resistance arteries and arterioles determines peripheral vascular resistance, contributing to the regulation of blood pressure and blood flow to, and within the body's tissues and organs. Ion channels in the plasma membrane and endoplasmic reticulum of vascular smooth muscle cells (SMCs) in these blood vessels importantly contribute to the regulation of intracellular Ca2+ concentration, the primary determinant of SMC contractile activity and vascular tone. Ion channels provide the main source of activator Ca2+ that determines vascular tone, and strongly contribute to setting and regulating membrane potential, which, in turn, regulates the open-state-probability of voltage gated Ca2+ channels (VGCCs), the primary source of Ca2+ in resistance artery and arteriolar SMCs. Ion channel function is also modulated by vasoconstrictors and vasodilators, contributing to all aspects of the regulation of vascular tone. This review will focus on the physiology of VGCCs, voltage-gated K+ (KV) channels, large-conductance Ca2+-activated K+ (BKCa) channels, strong-inward-rectifier K+ (KIR) channels, ATP-sensitive K+ (KATP) channels, ryanodine receptors (RyRs), inositol 1,4,5-trisphosphate receptors (IP3Rs), and a variety of transient receptor potential (TRP) channels that contribute to pressure-induced myogenic tone in resistance arteries and arterioles, the modulation of the function of these ion channels by vasoconstrictors and vasodilators, their role in the functional regulation of tissue blood flow and their dysfunction in diseases such as hypertension, obesity, and diabetes. © 2017 American Physiological Society. Compr Physiol 7:485-581, 2017.
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Affiliation(s)
- Nathan R Tykocki
- Department of Pharmacology, University of Vermont, Burlington, Vermont, USA
| | - Erika M Boerman
- Department of Medical Pharmacology and Physiology, University of Missouri, Columbia, Missouri, USA
| | - William F Jackson
- Department of Pharmacology and Toxicology, Michigan State University, East Lansing, Michigan, USA
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14
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Thodeti CK. Changing the Channels: Nature's Remote Controlling in Health and Disease. Circ Res 2017; 120:599-601. [PMID: 28209786 DOI: 10.1161/circresaha.117.310442] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Affiliation(s)
- Charles K Thodeti
- From the Department of Integrative Medical Sciences, Northeast Ohio Medical University, Rootstown.
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Nishijima Y, Cao S, Chabowski DS, Korishettar A, Ge A, Zheng X, Sparapani R, Gutterman DD, Zhang DX. Contribution of K V1.5 Channel to Hydrogen Peroxide-Induced Human Arteriolar Dilation and Its Modulation by Coronary Artery Disease. Circ Res 2016; 120:658-669. [PMID: 27872049 DOI: 10.1161/circresaha.116.309491] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/06/2016] [Revised: 11/11/2016] [Accepted: 11/21/2016] [Indexed: 02/06/2023]
Abstract
RATIONALE Hydrogen peroxide (H2O2) regulates vascular tone in the human microcirculation under physiological and pathophysiological conditions. It dilates arterioles by activating large-conductance Ca2+-activated K+ channels in subjects with coronary artery disease (CAD), but its mechanisms of action in subjects without CAD (non-CAD) when compared with those with CAD remain unknown. OBJECTIVE We hypothesize that H2O2-elicited dilation involves different K+ channels in non-CAD versus CAD, resulting in an altered capacity for vasodilation during disease. METHODS AND RESULTS H2O2 induced endothelium-independent vasodilation in non-CAD adipose arterioles, which was reduced by paxilline, a large-conductance Ca2+-activated K+ channel blocker, and by 4-aminopyridine, a voltage-gated K+ (KV) channel blocker. Assays of mRNA transcripts, protein expression, and subcellular localization revealed that KV1.5 is the major KV1 channel expressed in vascular smooth muscle cells and is abundantly localized on the plasma membrane. The selective KV1.5 blocker diphenylphosphine oxide-1 and the KV1.3/1.5 blocker 5-(4-phenylbutoxy)psoralen reduced H2O2-elicited dilation to a similar extent as 4-aminopyridine, but the selective KV1.3 blocker phenoxyalkoxypsoralen-1 was without effect. In arterioles from CAD subjects, H2O2-induced dilation was significantly reduced, and this dilation was inhibited by paxilline but not by 4-aminopyridine, diphenylphosphine oxide-1, or 5-(4-phenylbutoxy)psoralen. KV1.5 cell membrane localization and diphenylphosphine oxide-1-sensitive K+ currents were markedly reduced in isolated vascular smooth muscle cells from CAD arterioles, although mRNA or total cellular protein expression was largely unchanged. CONCLUSIONS In human arterioles, H2O2-induced dilation is impaired in CAD, which is associated with a transition from a combined large-conductance Ca2+-activated K+- and KV (KV1.5)-mediated vasodilation toward a large-conductance Ca2+-activated K+-predominant mechanism of dilation. Loss of KV1.5 vasomotor function may play an important role in microvascular dysfunction in CAD or other vascular diseases.
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Affiliation(s)
- Yoshinori Nishijima
- From the Department of Medicine (Y.N., S.C., D.S.C., A.K., A.G., X.Z., D.D.G., D.X.Z.), Cardiovascular Center (Y.N., S.C., D.S.C., A.K., A.G., X.Z., D.D.G., D.X.Z.), Department of Pharmacology and Toxicology (D.S.C., A.K.), Division of Biostatistics (R.S.), Medical College of Wisconsin, and Zablocki Veterans Affairs Medical Center (D.D.G.), Milwaukee, WI
| | - Sheng Cao
- From the Department of Medicine (Y.N., S.C., D.S.C., A.K., A.G., X.Z., D.D.G., D.X.Z.), Cardiovascular Center (Y.N., S.C., D.S.C., A.K., A.G., X.Z., D.D.G., D.X.Z.), Department of Pharmacology and Toxicology (D.S.C., A.K.), Division of Biostatistics (R.S.), Medical College of Wisconsin, and Zablocki Veterans Affairs Medical Center (D.D.G.), Milwaukee, WI
| | - Dawid S Chabowski
- From the Department of Medicine (Y.N., S.C., D.S.C., A.K., A.G., X.Z., D.D.G., D.X.Z.), Cardiovascular Center (Y.N., S.C., D.S.C., A.K., A.G., X.Z., D.D.G., D.X.Z.), Department of Pharmacology and Toxicology (D.S.C., A.K.), Division of Biostatistics (R.S.), Medical College of Wisconsin, and Zablocki Veterans Affairs Medical Center (D.D.G.), Milwaukee, WI
| | - Ankush Korishettar
- From the Department of Medicine (Y.N., S.C., D.S.C., A.K., A.G., X.Z., D.D.G., D.X.Z.), Cardiovascular Center (Y.N., S.C., D.S.C., A.K., A.G., X.Z., D.D.G., D.X.Z.), Department of Pharmacology and Toxicology (D.S.C., A.K.), Division of Biostatistics (R.S.), Medical College of Wisconsin, and Zablocki Veterans Affairs Medical Center (D.D.G.), Milwaukee, WI
| | - Alyce Ge
- From the Department of Medicine (Y.N., S.C., D.S.C., A.K., A.G., X.Z., D.D.G., D.X.Z.), Cardiovascular Center (Y.N., S.C., D.S.C., A.K., A.G., X.Z., D.D.G., D.X.Z.), Department of Pharmacology and Toxicology (D.S.C., A.K.), Division of Biostatistics (R.S.), Medical College of Wisconsin, and Zablocki Veterans Affairs Medical Center (D.D.G.), Milwaukee, WI
| | - Xiaodong Zheng
- From the Department of Medicine (Y.N., S.C., D.S.C., A.K., A.G., X.Z., D.D.G., D.X.Z.), Cardiovascular Center (Y.N., S.C., D.S.C., A.K., A.G., X.Z., D.D.G., D.X.Z.), Department of Pharmacology and Toxicology (D.S.C., A.K.), Division of Biostatistics (R.S.), Medical College of Wisconsin, and Zablocki Veterans Affairs Medical Center (D.D.G.), Milwaukee, WI
| | - Rodney Sparapani
- From the Department of Medicine (Y.N., S.C., D.S.C., A.K., A.G., X.Z., D.D.G., D.X.Z.), Cardiovascular Center (Y.N., S.C., D.S.C., A.K., A.G., X.Z., D.D.G., D.X.Z.), Department of Pharmacology and Toxicology (D.S.C., A.K.), Division of Biostatistics (R.S.), Medical College of Wisconsin, and Zablocki Veterans Affairs Medical Center (D.D.G.), Milwaukee, WI
| | - David D Gutterman
- From the Department of Medicine (Y.N., S.C., D.S.C., A.K., A.G., X.Z., D.D.G., D.X.Z.), Cardiovascular Center (Y.N., S.C., D.S.C., A.K., A.G., X.Z., D.D.G., D.X.Z.), Department of Pharmacology and Toxicology (D.S.C., A.K.), Division of Biostatistics (R.S.), Medical College of Wisconsin, and Zablocki Veterans Affairs Medical Center (D.D.G.), Milwaukee, WI
| | - David X Zhang
- From the Department of Medicine (Y.N., S.C., D.S.C., A.K., A.G., X.Z., D.D.G., D.X.Z.), Cardiovascular Center (Y.N., S.C., D.S.C., A.K., A.G., X.Z., D.D.G., D.X.Z.), Department of Pharmacology and Toxicology (D.S.C., A.K.), Division of Biostatistics (R.S.), Medical College of Wisconsin, and Zablocki Veterans Affairs Medical Center (D.D.G.), Milwaukee, WI.
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Santiago E, Martínez MP, Climent B, Muñoz M, Briones AM, Salaices M, García-Sacristán A, Rivera L, Prieto D. Augmented oxidative stress and preserved vasoconstriction induced by hydrogen peroxide in coronary arteries in obesity: role of COX-2. Br J Pharmacol 2016; 173:3176-3195. [PMID: 27535007 DOI: 10.1111/bph.13579] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2016] [Revised: 08/02/2016] [Accepted: 08/03/2016] [Indexed: 12/31/2022] Open
Abstract
BACKGROUND AND PURPOSE Oxidative stress plays a key role in the vascular and metabolic abnormalities associated with obesity. Herein, we assessed whether obesity can increase coronary vasoconstriction induced by hydrogen peroxide (H2 O2 ) and the signalling pathways involving COX-2 and superoxide (O2.- ) generation. EXPERIMENTAL APPROACH Contractile responses to H2 O2 and O2.- generation were measured in coronary arteries from genetically obese Zucker rats (OZR) and compared to lean Zucker rats (LZR). KEY RESULTS Both basal and H2 O2 -stimulated O2.- production were enhanced in coronary arteries from OZR, but H2 O2 -induced vasoconstriction was unchanged. The selective COX-2 inhibitor NS398 significantly reduced H2 O2 -induced contractions in endothelium-denuded arteries from LZR and OZR, but only in endothelium-intact arteries from LZR. PGI2 (IP) receptor antagonism modestly reduced the vasoconstrictor action of H2 O2 while antagonism of the PGE2 receptor 4 (EP4 ) enhanced H2 O2 contractions in arteries from OZR but not LZR. Basal release of COX-2-derived PGE2 was higher in coronary arteries from OZR where the selective agonist of EP4 receptors TCS 2519 evoked potent relaxations. COX-2 was up-regulated after acute exposure to H2 O2 in coronary endothelium and vascular smooth muscle (VSM) and inhibition of COX-2 markedly reduced H2 O2 -elicited O2.- generation in coronary arteries and myocardium. Expression of Nox subunits in VSM and NADPH-stimulated O2.- generation was enhanced and contributed to H2 O2 vasoconstriction in arteries from obese rats. CONCLUSION AND IMPLICATIONS COX-2 contributes to cardiac oxidative stress and to the endothelium-independent O2.- -mediated coronary vasoconstriction induced by H2 O2 in obesity, which is offset by the release of COX-2-derived endothelial PGE2 acting on EP4 vasodilator receptors.
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Affiliation(s)
- Elvira Santiago
- Departamento de Fisiología, Facultad de Farmacia, Universidad Complutense de Madrid, Madrid, Spain
| | - Maria Pilar Martínez
- Departamento de Anatomía and Anatomía Patológica Comparadas, Facultad de Veterinaria, Universidad Complutense de Madrid, Madrid, Spain
| | - Belén Climent
- Departamento de Fisiología, Facultad de Farmacia, Universidad Complutense de Madrid, Madrid, Spain
| | - Mercedes Muñoz
- Departamento de Fisiología, Facultad de Farmacia, Universidad Complutense de Madrid, Madrid, Spain
| | - Ana María Briones
- Departamento de Farmacología, Facultad de Medicina, Instituto de Investigación Hospital Universitario La Paz (IdiPAZ), Universidad Autónoma de Madrid, Madrid, Spain
| | - Mercedes Salaices
- Departamento de Farmacología, Facultad de Medicina, Instituto de Investigación Hospital Universitario La Paz (IdiPAZ), Universidad Autónoma de Madrid, Madrid, Spain
| | - Albino García-Sacristán
- Departamento de Fisiología, Facultad de Farmacia, Universidad Complutense de Madrid, Madrid, Spain
| | - Luis Rivera
- Departamento de Fisiología, Facultad de Farmacia, Universidad Complutense de Madrid, Madrid, Spain
| | - Dolores Prieto
- Departamento de Fisiología, Facultad de Farmacia, Universidad Complutense de Madrid, Madrid, Spain.
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Chidgey J, Fraser PA, Aaronson PI. Reactive oxygen species facilitate the EDH response in arterioles by potentiating intracellular endothelial Ca(2+) release. Free Radic Biol Med 2016; 97:274-284. [PMID: 27320188 PMCID: PMC5005039 DOI: 10.1016/j.freeradbiomed.2016.06.010] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/17/2016] [Revised: 06/14/2016] [Accepted: 06/15/2016] [Indexed: 11/17/2022]
Abstract
There is abundant evidence that H2O2 can act as an endothelium-derived hyperpolarizing factor in the resistance vasculature. However, whilst scavenging H2O2 can abolish endothelial dependent hyperpolarization (EDH) and the associated vascular relaxation in some arteries, EDH-dependent vasorelaxation can often be mimicked only by using relatively high concentrations of H2O2. We have examined the role of H2O2 in EDH-dependent vasodilatation by simultaneously measuring vascular diameter and changes in endothelial cell (EC) [Ca(2+)]i during the application of H2O2 or carbachol, which triggers EDH. Carbachol (10µM) induced dilatation of phenylephrine-preconstricted rat cremaster arterioles was largely (73%) preserved in the presence of indomethacin (3µM) and l-NAME (300µM). This residual NO- and prostacyclin-independent dilatation was reduced by 89% upon addition of apamin (0.5µM) and TRAM-34 (10µM), and by 74% when an extracellular ROS scavenging mixture of SOD and catalase (S&C; 100Uml(-1) each) was present. S&C also reduced the carbachol-induced EC [Ca(2+)]i increase by 74%. When applied in Ca(2+)-free external medium, carbachol caused a transient increase in EC [Ca(2+)]i. This was reduced by catalase, and was enhanced when 1µM H2O2 was present in the bath. H2O2 -induced dilatation, which occurred only at concentrations ≥100µM, was reduced by a blocking antibody to TRPM2, which had no effect on carbachol-induced responses. Similarly, iberotoxin and Rp-8bromo cGMP reduced the vasodilatation induced by H2O2, but not by carbachol. Inhibiting PLC, PLA2 or CYP450 2C9 each greatly reduced the carbachol-induced increase in EC [Ca(2+)]i and vasodilatation, but adding 10µM H2O2 during PLA2 or CYP450 2C9 inhibition completely restored both responses. The nature of the effective ROS species was investigated by using Fe(2+) chelators to block the formation of ∙OH. A cell permeant chelator was able to inhibit EC Ca(2+) store release, but cell impermeant chelators reduced both the vasodilatation and EC Ca(2+) influx, implying that ∙OH is required for these responses. The results indicate that rather than mediating EDH by acting directly on smooth muscle, H2O2 promotes EDH by acting within EC to enhance Ca(2+) release.
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Affiliation(s)
- James Chidgey
- King's College London, Faculty of Life Sciences and Medicine, Division of Asthma, Allergy & Lung Biology, London, United Kingdom
| | - Paul A Fraser
- King's College London, Faculty of Life Sciences and Medicine, Cardiovascular Division, London, United Kingdom
| | - Philip I Aaronson
- King's College London, Faculty of Life Sciences and Medicine, Division of Asthma, Allergy & Lung Biology, London, United Kingdom.
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Differential regulation of TRPV1 channels by H2O2: implications for diabetic microvascular dysfunction. Basic Res Cardiol 2016; 111:21. [PMID: 26907473 DOI: 10.1007/s00395-016-0539-4] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/18/2015] [Accepted: 02/11/2016] [Indexed: 12/21/2022]
Abstract
We demonstrated previously that TRPV1-dependent coupling of coronary blood flow (CBF) to metabolism is disrupted in diabetes. A critical amount of H2O2 contributes to CBF regulation; however, excessive H2O2 impairs responses. We sought to determine the extent to which differential regulation of TRPV1 by H2O2 modulates CBF and vascular reactivity in diabetes. We used contrast echocardiography to study TRPV1 knockout (V1KO), db/db diabetic, and wild type C57BKS/J (WT) mice. H2O2 dose-dependently increased CBF in WT mice, a response blocked by the TRPV1 antagonist SB366791. H2O2-induced vasodilation was significantly inhibited in db/db and V1KO mice. H2O2 caused robust SB366791-sensitive dilation in WT coronary microvessels; however, this response was attenuated in vessels from db/db and V1KO mice, suggesting H2O2-induced vasodilation occurs, in part, via TRPV1. Acute H2O2 exposure potentiated capsaicin-induced CBF responses and capsaicin-mediated vasodilation in WT mice, whereas prolonged luminal H2O2 exposure blunted capsaicin-induced vasodilation. Electrophysiology studies re-confirms acute H2O2 exposure activated TRPV1 in HEK293A and bovine aortic endothelial cells while establishing that H2O2 potentiate capsaicin-activated TRPV1 currents, whereas prolonged H2O2 exposure attenuated TRPV1 currents. Verification of H2O2-mediated activation of intrinsic TRPV1 specific currents were found in isolated mouse coronary endothelial cells from WT mice and decreased in endothelial cells from V1KO mice. These data suggest prolonged H2O2 exposure impairs TRPV1-dependent coronary vascular signaling. This may contribute to microvascular dysfunction and tissue perfusion deficits characteristic of diabetes.
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Santiago E, Climent B, Muñoz M, García-Sacristán A, Rivera L, Prieto D. Hydrogen peroxide activates store-operated Ca(2+) entry in coronary arteries. Br J Pharmacol 2015; 172:5318-32. [PMID: 26478127 DOI: 10.1111/bph.13322] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2015] [Revised: 08/20/2015] [Accepted: 09/06/2015] [Indexed: 12/27/2022] Open
Abstract
BACKGROUND AND PURPOSE Abnormal Ca(2+) metabolism has been involved in the pathogenesis of vascular dysfunction associated with oxidative stress. Here, we have investigated the actions of H2 O2 on store-operated Ca(2+) (SOC) entry in coronary arteries and assessed whether it is impaired in arteries from a rat model of metabolic syndrome. EXPERIMENTAL APPROACH Simultaneous measurements of intracellular Ca(2+) concentration and contractile responses were made in coronary arteries from Wistar and obese Zucker rats, mounted in microvascular myographs, and the effects of H2 O2 were assessed. KEY RESULTS H2 O2 raised intracellular Ca(2+) concentrations, accompanied by simultaneous vasoconstriction that was markedly reduced in a Ca(2+) -free medium. Upon Ca(2+) re-addition, a nifedipine-resistant sustained Ca(2+) entry, not coupled to contraction, was obtained in endothelium-denuded coronary arteries. The effect of H2 O2 on this voltage-independent Ca(2+) influx was concentration-dependent, and high micromolar H2 O2 concentrations were inhibitory and reduced SOC entry evoked by inhibition of the sarcoplasmic reticulum ATPase (SERCA). H2 O2 -induced increases in Fura signals were mimicked by Ba(2+) and reduced by heparin, Gd(3+) ions and by Pyr6, a selective inhibitor of the Orai1-mediated Ca(2+) entry,. In coronary arteries from obese Zucker rats, intracellular Ca(2+) mobilization and SOC entry activated by acute exposure to H2 O2 were augmented and associated with local oxidative stress. CONCLUSION AND IMPLICATIONS H2 O2 exerted dual concentration-dependent stimulatory/inhibitory effects on store-operated, IP3 receptor-mediated and Orai1-mediated Ca(2+) entry, not coupled to vasoconstriction in coronary vascular smooth muscle. SOC entry activated by H2 O2 was enhanced and associated with vascular oxidative stress in coronary arteries in metabolic syndrome.
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Affiliation(s)
- Elvira Santiago
- Departamento de Fisiología, Facultad de Farmacia, Universidad Complutense de Madrid, Madrid, Spain
| | - Belén Climent
- Departamento de Fisiología, Facultad de Farmacia, Universidad Complutense de Madrid, Madrid, Spain
| | - Mercedes Muñoz
- Departamento de Fisiología, Facultad de Farmacia, Universidad Complutense de Madrid, Madrid, Spain
| | - Albino García-Sacristán
- Departamento de Fisiología, Facultad de Farmacia, Universidad Complutense de Madrid, Madrid, Spain
| | - Luis Rivera
- Departamento de Fisiología, Facultad de Farmacia, Universidad Complutense de Madrid, Madrid, Spain
| | - Dolores Prieto
- Departamento de Fisiología, Facultad de Farmacia, Universidad Complutense de Madrid, Madrid, Spain
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Chabowski D, Gutterman D. Unveiling the Mechanism of Coronary Metabolic Vasodilation: Voltage-Gated Potassium Channels and Hydrogen Peroxide. Circ Res 2015; 117:589-91. [PMID: 26358107 DOI: 10.1161/circresaha.115.307281] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Affiliation(s)
- Dawid Chabowski
- From the Departments of Medicine (D.G.) and Pharmacology and Toxicology (D.C., D.G.), Cardiovascular Center, Medical College of Wisconsin, Milwaukee
| | - David Gutterman
- From the Departments of Medicine (D.G.) and Pharmacology and Toxicology (D.C., D.G.), Cardiovascular Center, Medical College of Wisconsin, Milwaukee.
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Hermann A, Sitdikova GF, Weiger TM. Oxidative Stress and Maxi Calcium-Activated Potassium (BK) Channels. Biomolecules 2015; 5:1870-911. [PMID: 26287261 PMCID: PMC4598779 DOI: 10.3390/biom5031870] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2015] [Revised: 07/17/2015] [Accepted: 07/20/2015] [Indexed: 01/13/2023] Open
Abstract
All cells contain ion channels in their outer (plasma) and inner (organelle) membranes. Ion channels, similar to other proteins, are targets of oxidative impact, which modulates ion fluxes across membranes. Subsequently, these ion currents affect electrical excitability, such as action potential discharge (in neurons, muscle, and receptor cells), alteration of the membrane resting potential, synaptic transmission, hormone secretion, muscle contraction or coordination of the cell cycle. In this chapter we summarize effects of oxidative stress and redox mechanisms on some ion channels, in particular on maxi calcium-activated potassium (BK) channels which play an outstanding role in a plethora of physiological and pathophysiological functions in almost all cells and tissues. We first elaborate on some general features of ion channel structure and function and then summarize effects of oxidative alterations of ion channels and their functional consequences.
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Affiliation(s)
- Anton Hermann
- Department of Cell Biology, Division of Cellular and Molecular Neurobiology, University of Salzburg, Salzburg 5020, Austria.
| | - Guzel F Sitdikova
- Department of Physiology of Man and Animals, Kazan Federal University, Kazan 420008, Russia.
| | - Thomas M Weiger
- Department of Cell Biology, Division of Cellular and Molecular Neurobiology, University of Salzburg, Salzburg 5020, Austria.
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Csató V, Pető A, Koller Á, Édes I, Tóth A, Papp Z. Hydrogen peroxide elicits constriction of skeletal muscle arterioles by activating the arachidonic acid pathway. PLoS One 2014; 9:e103858. [PMID: 25093847 PMCID: PMC4122381 DOI: 10.1371/journal.pone.0103858] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2014] [Accepted: 07/02/2014] [Indexed: 02/07/2023] Open
Abstract
Aims The molecular mechanisms of the vasoconstrictor responses evoked by hydrogen peroxide (H2O2) have not been clearly elucidated in skeletal muscle arterioles. Methods and Results Changes in diameter of isolated, cannulated and pressurized gracilis muscle arterioles (GAs) of Wistar-Kyoto rats were determined under various test conditions. H2O2 (10–100 µM) evoked concentration-dependent constrictions in the GAs, which were inhibited by endothelium removal, or by antagonists of phospholipase A (PLA; 100 µM 7,7-dimethyl-(5Z,8Z)-eicosadienoic acid), protein kinase C (PKC; 10 µM chelerythrine), phospholipase C (PLC; 10 µM U-73122), or Src family tyrosine kinase (Src kinase; 1 µM Src Inhibitor-1). Antagonists of thromboxane A2 (TXA2; 1 µM SQ-29548) or the non-specific cyclooxygenase (COX) inhibitor indomethacin (10 µM) converted constrictions to dilations. The COX-1 inhibitor (SC-560, 1 µM) demonstrated a greater reduction in constriction and conversion to dilation than that of COX-2 (celecoxib, 3 µM). H2O2 did not elicit significant changes in arteriolar Ca2+ levels measured with Fura-2. Conclusions These data suggest that H2O2 activates the endothelial Src kinase/PLC/PKC/PLA pathway, ultimately leading to the synthesis and release of TXA2 by COX-1, thereby increasing the Ca2+ sensitivity of the vascular smooth muscle cells and eliciting constriction in rat skeletal muscle arterioles.
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Affiliation(s)
- Viktória Csató
- Division of Clinical Physiology, Institute of Cardiology, University of Debrecen, Debrecen, Hungary
- Research Centre for Molecular Medicine, University of Debrecen, Debrecen, Hungary
| | - Attila Pető
- Division of Clinical Physiology, Institute of Cardiology, University of Debrecen, Debrecen, Hungary
- Research Centre for Molecular Medicine, University of Debrecen, Debrecen, Hungary
| | - Ákos Koller
- Department of Pathophysiology and Gerontology, University of Pécs, Pécs, Hungary
- Department of Pathophysiology, Semmelweis University, Budapest, Hungary
- Department of Physiology, New York Medical College, Valhalla, New York, United States of America
| | - István Édes
- Division of Clinical Physiology, Institute of Cardiology, University of Debrecen, Debrecen, Hungary
- Research Centre for Molecular Medicine, University of Debrecen, Debrecen, Hungary
| | - Attila Tóth
- Division of Clinical Physiology, Institute of Cardiology, University of Debrecen, Debrecen, Hungary
- Research Centre for Molecular Medicine, University of Debrecen, Debrecen, Hungary
| | - Zoltán Papp
- Division of Clinical Physiology, Institute of Cardiology, University of Debrecen, Debrecen, Hungary
- Research Centre for Molecular Medicine, University of Debrecen, Debrecen, Hungary
- * E-mail:
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Kalogeris T, Bao Y, Korthuis RJ. Mitochondrial reactive oxygen species: a double edged sword in ischemia/reperfusion vs preconditioning. Redox Biol 2014; 2:702-14. [PMID: 24944913 PMCID: PMC4060303 DOI: 10.1016/j.redox.2014.05.006] [Citation(s) in RCA: 512] [Impact Index Per Article: 51.2] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2014] [Revised: 05/23/2014] [Accepted: 05/27/2014] [Indexed: 02/06/2023] Open
Abstract
Reductions in the blood supply produce considerable injury if the duration of ischemia is prolonged. Paradoxically, restoration of perfusion to ischemic organs can exacerbate tissue damage and extend the size of an evolving infarct. Being highly metabolic organs, the heart and brain are particularly vulnerable to the deleterious effects of ischemia/reperfusion (I/R). While the pathogenetic mechanisms contributing to I/R-induced tissue injury and infarction are multifactorial, the relative importance of each contributing factor remains unclear. However, an emerging body of evidence indicates that the generation of reactive oxygen species (ROS) by mitochondria plays a critical role in damaging cellular components and initiating cell death. In this review, we summarize our current understanding of the mechanisms whereby mitochondrial ROS generation occurs in I/R and contributes to myocardial infarction and stroke. In addition, mitochondrial ROS have been shown to participate in preconditioning by several pharmacologic agents that target potassium channels (e.g., ATP-sensitive potassium (mKATP) channels or large conductance, calcium-activated potassium (mBKCa) channels) to activate cell survival programs that render tissues and organs more resistant to the deleterious effects of I/R. Finally, we review novel therapeutic approaches that selectively target mROS production to reduce postischemic tissue injury, which may prove efficacious in limiting myocardial dysfunction and infarction and abrogating neurocognitive deficits and neuronal cell death in stroke.
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Affiliation(s)
- Theodore Kalogeris
- Department of Medical Pharmacology and Physiology, School of Medicine, Dalton Cardiovascular Research Center, University of Missouri, 1 Hospital Drive, Columbia, MO 65212-0001, United States of America
| | - Yimin Bao
- Department of Medical Pharmacology and Physiology, School of Medicine, Dalton Cardiovascular Research Center, University of Missouri, 1 Hospital Drive, Columbia, MO 65212-0001, United States of America
| | - Ronald J Korthuis
- Department of Medical Pharmacology and Physiology, School of Medicine, Dalton Cardiovascular Research Center, University of Missouri, 1 Hospital Drive, Columbia, MO 65212-0001, United States of America
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Hydrogen peroxide induces vasorelaxation by enhancing 4-aminopyridine-sensitive Kv currents through S-glutathionylation. Pflugers Arch 2014; 467:285-97. [PMID: 24756196 PMCID: PMC4293500 DOI: 10.1007/s00424-014-1513-3] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2013] [Revised: 01/04/2014] [Accepted: 04/02/2014] [Indexed: 12/04/2022]
Abstract
Hydrogen peroxide (H2O2) is an endothelium-derived hyperpolarizing factor. Since opposing vasoactive effects have been reported for H2O2 depending on the vascular bed and experimental conditions, this study was performed to assess whether H2O2 acts as a vasodilator in the rat mesenteric artery and, if so, to determine the underlying mechanisms. H2O2 elicited concentration-dependent relaxation in mesenteric arteries precontracted with norepinephrine. The vasodilatory effect of H2O2 was reversed by treatment with dithiothreitol. H2O2-elicited vasodilation was significantly reduced by blocking 4-aminopyridine (4-AP)-sensitive Kv channels, but it was resistant to blockers of big-conductance Ca2+-activated K+ channels and inward rectifier K+ channels. A patch-clamp study in mesenteric arterial smooth muscle cells (MASMCs) showed that H2O2 increased Kv currents in a concentration-dependent manner. H2O2 speeded up Kv channel activation and shifted steady state activation to hyperpolarizing potentials. Similar channel activation was seen with oxidized glutathione (GSSG). The H2O2-mediated channel activation was prevented by glutathione reductase. Consistent with S-glutathionylation, streptavidin pull-down assays with biotinylated glutathione ethyl ester showed incorporation of glutathione (GSH) in the Kv channel proteins in the presence of H2O2. Interestingly, conditions of increased oxidative stress within MASMCs impaired the capacity of H2O2 to stimulate Kv channels. Not only was the H2O2 stimulatory effect much weaker, but the inhibitory effect of H2O2 was unmasked. These data suggest that H2O2 activates 4-AP-sensitive Kv channels, possibly through S-glutathionylation, which elicits smooth muscle relaxation in rat mesenteric arteries. Furthermore, our results support the idea that the basal redox status of MASMCs determines the response of Kv currents to H2O2.
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25
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Fujii N, Brunt VE, Minson CT. Tempol improves cutaneous thermal hyperemia through increasing nitric oxide bioavailability in young smokers. Am J Physiol Heart Circ Physiol 2014; 306:H1507-11. [PMID: 24682395 DOI: 10.1152/ajpheart.00886.2013] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
We recently found that young cigarette smokers display cutaneous vascular dysfunction relative to nonsmokers, which is partially due to reduced nitric oxide (NO) synthase (NOS)-dependent vasodilation. In this study, we tested the hypothesis that reducing oxidative stress improves NO bioavailability, enhancing cutaneous vascular function in young smokers. Ten healthy young male smokers, who had smoked for 6.3 ± 0.7 yr with an average daily consumption of 9.1 ± 0.7 cigarettes, were tested. Cutaneous vascular conductance (CVC) during local heating to 42°C at a rate of 0.1°C/s was evaluated as laser-Doppler flux divided by mean arterial blood pressure and normalized to maximal CVC, induced by local heating to 44°C plus sodium nitroprusside administration. We evaluated plateau CVC during local heating, which is known to be highly dependent on NO, at four intradermal microdialysis sites with 1) Ringer solution (control); 2) 10 μM 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl (tempol), a superoxide dismutase mimetic; 3) 10 mM N(ω)-nitro-l-arginine (l-NNA), a nonspecific NOS inhibitor; and 4) a combination of 10 μM tempol and 10 mM l-NNA. Tempol increased plateau CVC compared with the Ringer solution site (90.0 ± 2.3 vs. 77.6 ± 3.9%maximum, P = 0.028). Plateau CVC at the combination site (56.8 ± 4.5%maximum) was lower than the Ringer solution site (P < 0.001) and was not different from the l-NNA site (55.1 ± 4.6%maximum, P = 0.978), indicating the tempol effect was exclusively NO dependent. These data suggest that in young smokers, reducing oxidative stress improves cutaneous thermal hyperemia to local heating by enhancing NO production.
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Affiliation(s)
- Naoto Fujii
- Department of Human Physiology, The University of Oregon, Eugene, Oregon
| | - Vienna E Brunt
- Department of Human Physiology, The University of Oregon, Eugene, Oregon
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26
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Xie W, Parker JL, Heaps CL. Exercise training-enhanced, endothelium-dependent dilation mediated by altered regulation of BK(Ca) channels in collateral-dependent porcine coronary arterioles. Microcirculation 2013; 20:170-82. [PMID: 23002811 DOI: 10.1111/micc.12016] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2012] [Accepted: 09/19/2012] [Indexed: 12/21/2022]
Abstract
OBJECTIVE Test the hypothesis that exercise training increases the contribution of BK(Ca) channels to endothelium-mediated dilation in coronary arterioles from collateral-dependent myocardial regions of chronically occluded pig hearts and may function downstream of H2O2. METHODS An ameroid constrictor was placed around the proximal left circumflex coronary artery to induce gradual occlusion in Yucatan miniature swine. Eight weeks postoperatively, pigs were randomly assigned to sedentary or exercise training (treadmill; 14 week) regimens. RESULTS Exercise training significantly enhanced bradykinin-mediated dilation in collateral-dependent arterioles (~125 μm diameter) compared with sedentary pigs. The BK(Ca) -channel blocker, iberiotoxin alone or in combination with the H2O2 scavenger, polyethylene glycol catalase, reversed exercise training-enhanced dilation in collateral-dependent arterioles. Iberiotoxin-sensitive whole-cell K+ currents (i.e., BK(Ca)-channel currents) were not different between smooth muscle cells of nonoccluded and collateral-dependent arterioles of sedentary and exercise trained groups. CONCLUSIONS These data provide evidence that BK(Ca)-channel activity contributes to exercise training-enhanced endothelium-dependent dilation in collateral-dependent coronary arterioles despite no change in smooth muscle BK(Ca)-channel current. Taken together, our findings suggest that a component of the bradykinin signaling pathway, which stimulates BK(Ca) channels, is enhanced by exercise training in collateral-dependent arterioles and suggest a potential role for H2O2 as the mediator.
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Affiliation(s)
- Wei Xie
- Department of Veterinary Physiology & Pharmacology, Texas A&M University, College Station, Texas, USA
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27
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Choi S, Na HY, Kim JA, Cho SE, Suh SH. Contradictory Effects of Superoxide and Hydrogen Peroxide on KCa3.1 in Human Endothelial Cells. THE KOREAN JOURNAL OF PHYSIOLOGY & PHARMACOLOGY : OFFICIAL JOURNAL OF THE KOREAN PHYSIOLOGICAL SOCIETY AND THE KOREAN SOCIETY OF PHARMACOLOGY 2013; 17:181-7. [PMID: 23776393 PMCID: PMC3682077 DOI: 10.4196/kjpp.2013.17.3.181] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/14/2013] [Revised: 05/15/2013] [Accepted: 05/20/2013] [Indexed: 01/18/2023]
Abstract
Reactive oxygen species (ROS) are generated in various cells, including vascular smooth muscle and endothelial cells, and regulate ion channel functions. KCa3.1 plays an important role in endothelial functions. However, the effects of superoxide and hydrogen peroxide radicals on the expression of this ion channel in the endothelium remain unclear. In this study, we examined the effects of ROS donors on KCa3.1 expression and the K+ current in primary cultured human umbilical vein endothelial cells (HUVECs). The hydrogen peroxide donor, tert-butyl hydroperoxide (TBHP), upregulated KCa3.1 expression, while the superoxide donors, xanthine/xanthine oxidase mixture (X/XO) and lysopho-sphatidylcholine (LPC), downregulated its expression, in a concentration-dependent manner. These ROS donor effects were prevented by antioxidants or superoxide dismustase. Phosphorylated extracellular signal-regulated kinase (pERK) was upregulated by TBHP and downregulated by X/XO. In addition, repressor element-1-silencing transcription factor (REST) was downregulated by TBHP, and upregulated by X/XO. Furthermore, KCa3.1 current, which was activated by clamping cells with 1 µM Ca2+ and applying the KCa3.1 activator 1-ethyl-2-benzimidazolinone, was further augmented by TBHP, and inhibited by X/XO. These effects were prevented by antioxidants. The results suggest that hydrogen peroxide increases KCa3.1 expression by upregulating pERK and downregulating REST, and augments the K+ current. On the other hand, superoxide reduces KCa3.1 expression by downregulating pERK and upregulating REST, and inhibits the K+ current. ROS thereby play a key role in both physiological and pathological processes in endothelial cells by regulating KCa3.1 and endothelial function.
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Affiliation(s)
- Shinkyu Choi
- Department of Physiology and Medical Research Institute, School of Medicine, Ewha Womans University, Seoul 158-710, Korea
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28
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Sharifi-Sanjani M, Zhou X, Asano S, Tilley S, Ledent C, Teng B, Dick GM, Mustafa SJ. Interactions between A(2A) adenosine receptors, hydrogen peroxide, and KATP channels in coronary reactive hyperemia. Am J Physiol Heart Circ Physiol 2013; 304:H1294-301. [PMID: 23525711 DOI: 10.1152/ajpheart.00637.2012] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Myocardial metabolites such as adenosine mediate reactive hyperemia, in part, by activating ATP-dependent K(+) (K(ATP)) channels in coronary smooth muscle. In this study, we investigated the role of adenosine A(2A) and A(2B) receptors and their signaling mechanisms in reactive hyperemia. We hypothesized that coronary reactive hyperemia involves A(2A) receptors, hydrogen peroxide (H(2)O(2)), and KATP channels. We used A(2A) and A(2B) knockout (KO) and A(2A/2B) double KO (DKO) mouse hearts for Langendorff experiments. Flow debt for a 15-s occlusion was repaid 128 ± 8% in hearts from wild-type (WT) mice; this was reduced in hearts from A(2A) KO and A(2A)/(2B) DKO mice (98 ± 9 and 105 ± 6%; P < 0.05), but not A(2B) KO mice (123 ± 13%). Patch-clamp experiments demonstrated that adenosine activated glibenclamide-sensitive KATP current in smooth muscle cells from WT and A(2B) KO mice (90 ± 23% of WT) but not A(2A) KO or A(2A)/A(2B) DKO mice (30 ± 4 and 35 ± 8% of WT; P < 0.05). Additionally, H(2)O(2) activated KATP current in smooth muscle cells (358 ± 99%; P < 0.05). Catalase, an enzyme that breaks down H(2)O(2), attenuated adenosine-induced coronary vasodilation, reducing the percent increase in flow from 284 ± 53 to 89 ± 13% (P < 0.05). Catalase reduced the repayment of flow debt in hearts from WT mice (84 ± 9%; P < 0.05) but had no effect on the already diminished repayment in hearts from A(2A) KO mice (98 ± 7%). Our findings suggest that adenosine A(2A) receptors are coupled to smooth muscle KATP channels in reactive hyperemia via the production of H(2)O(2) as a signaling intermediate.
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Affiliation(s)
- Maryam Sharifi-Sanjani
- Department of Physiology and Pharmacology, West Virginia University, Morgantown, WV 26506, USA
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29
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Ko EA, Wan J, Yamamura A, Zimnicka AM, Yamamura H, Yoo HY, Tang H, Smith KA, Sundivakkam PC, Zeifman A, Ayon RJ, Makino A, Yuan JXJ. Functional characterization of voltage-dependent Ca(2+) channels in mouse pulmonary arterial smooth muscle cells: divergent effect of ROS. Am J Physiol Cell Physiol 2013; 304:C1042-52. [PMID: 23426966 DOI: 10.1152/ajpcell.00304.2012] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Electromechanical coupling via membrane depolarization-mediated activation of voltage-dependent Ca(2+) channels (VDCC) is an important mechanism in regulating pulmonary vascular tone, while mouse is an animal model often used to study pathogenic mechanisms of pulmonary vascular disease. The function of VDCC in mouse pulmonary artery (PA) smooth muscle cells (PASMC), however, has not been characterized, and their functional role in reactive oxygen species (ROS)-mediated regulation of vascular function remains unclear. In this study, we characterized the electrophysiological and pharmacological properties of VDCC in PASMC and the divergent effects of ROS produced by xanthine oxidase (XO) and hypoxanthine (HX) on VDCC in PA and mesenteric artery (MA). Our data show that removal of extracellular Ca(2+) or application of nifedipine, a dihydropyridine VDCC blocker, both significantly inhibited 80 mM K(+)-mediated PA contraction. In freshly dissociated PASMC, the maximum inward Ca(2+) currents were -2.6 ± 0.2 pA/pF at +10 mV (with a holding potential of -70 mV). Window currents were between -40 and +10 mV with a peak at -15.4 mV. Nifedipine inhibited currents with an IC(50) of 0.023 μM, and 1 μM Bay K8644, a dihydropyridine VDCC agonist, increased the inward currents by 61%. XO/HX attenuated 60 mM K(+)-mediated increase in cytosolic free Ca(2+) concentration ([Ca(2+)](cyt)) due to Ca(2+) influx through VDCC in PASMC. Exposure to XO/HX caused relaxation in PA preconstricted by 80 mM K(+) but not in aorta and MA. In contrast, H(2)O(2) inhibited high K(+)-mediated increase in [Ca(2+)](cyt) and caused relaxation in both PA and MA. Indeed, RT-PCR and Western blot analysis revealed significantly lower expression of Ca(V)1.3 in MA compared with PA. Thus our study characterized the properties of VDCC and demonstrates that ROS differentially regulate vascular contraction by regulating VDCC in PA and systemic arteries.
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Affiliation(s)
- Eun A Ko
- Department of Medicine, Section of Pulmonary, Critical Care, Sleep and Allergy Medicine, University of Illinois at Chicago, Chicago, IL 60612, USA
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30
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Puri N, Zhang F, Monu SR, Sodhi K, Bellner L, Lamon BD, Zhang Y, Abraham NG, Nasjletti A. Antioxidants condition pleiotropic vascular responses to exogenous H(2)O(2): role of modulation of vascular TP receptors and the heme oxygenase system. Antioxid Redox Signal 2013; 18:471-80. [PMID: 22867102 PMCID: PMC3545357 DOI: 10.1089/ars.2012.4587] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/27/2012] [Revised: 08/06/2012] [Accepted: 08/07/2012] [Indexed: 11/13/2022]
Abstract
AIMS Hydrogen peroxide (H(2)O(2)), a nonradical oxidant, is employed to ascertain the role of redox mechanisms in regulation of vascular tone. Where both dilation and constriction have been reported, we examined the hypothesis that the ability of H(2)O(2) to effect vasoconstriction or dilation is conditioned by redox mechanisms and may be modulated by antioxidants. RESULTS Exogenous H(2)O(2) (0.1-10.0 μM), dose-dependently reduced the internal diameter of rat renal interlobular and 3rd-order mesenteric arteries (p<0.05). This response was obliterated in arteries pretreated with antioxidants, including tempol, pegylated superoxide dismutase (PEG-SOD), butylated hydroxytoluene (BHT), and biliverdin (BV). However, as opposed to tempol or PEG-SOD, BHT & BV, antioxidants targeting radicals downstream of H(2)O(2), also uncovered vasodilation. INNOVATIONS Redox-dependent vasoconstriction to H(2)O(2) was blocked by inhibitors of cyclooxygenase (COX) (indomethacin-10 μM), thromboxane (TP) synthase (CGS13080-10 μM), and TP receptor antagonist (SQ29548-1 μM). However, H(2)O(2) did not increase vascular thromboxane B(2) release; instead, it sensitized the vasculature to a TP agonist, U46619, an effect reversed by PEG-SOD. Antioxidant-conditioned dilatory response to H(2)O(2) was accompanied by enhanced vascular heme oxygenase (HO)-dependent carbon monoxide generation and was abolished by HO inhibitors or by HO-1 & 2 antisense oligodeoxynucleotides treatment of SD rats. CONCLUSION These results demonstrate that H(2)O(2) has antioxidant-modifiable pleiotropic vascular effects, where constriction and dilation are brought about in the same vascular segment. H(2)O(2)-induced oxidative stress increases vascular TP sensitivity and predisposes these arterial segments to constrictor prostanoids. Conversely, vasodilation is reliant upon HO-derived products whose synthesis is stimulated only in the presence of antioxidants targeting radicals downstream of H(2)O(2).
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Affiliation(s)
- Nitin Puri
- Department of Pharmacology, New York Medical College, Valhalla, New York, USA.
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31
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Muller-Delp JM, Gurovich AN, Christou DD, Leeuwenburgh C. Redox balance in the aging microcirculation: new friends, new foes, and new clinical directions. Microcirculation 2012; 19:19-28. [PMID: 21954960 DOI: 10.1111/j.1549-8719.2011.00139.x] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Cardiovascular aging is associated with a decline in the function of the vascular endothelium. Considerable evidence indicates that age-induced impairment of endothelium-dependent vasodilation results from a reduction in the availability of nitric oxide (NO(•) ). NO(•) can be scavenged by reactive oxygen species (ROS), in particular by superoxide radical (O(2) (•-) ), and age-related increases in ROS have been demonstrated to contribute to reduced endothelium-dependent vasodilation in numerous large artery preparations. In contrast, emerging data suggest that ROS may play a compensatory role in endothelial function of the aging microvasculature. The primary goal of this review is to discuss reports in the literature which indicate that ROS function as important signaling molecules in the aging microvasculature. Emphasis is placed upon discussion of the emerging roles of hydrogen peroxide (H(2) O(2) ) and peroxynitrite (ONOO(•-) ) in the aging microcirculation. Overall, existing data in animal models suggest that maintenance in the balance of ROS is critical to successful microvascular aging. The limited work that has been performed to investigate the role of ROS in human microvascular aging is also discussed, and the need for future investigations of ROS signaling in older humans is considered.
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Affiliation(s)
- Judy M Muller-Delp
- Department of Physiology and Functional Genomics, University of Florida, Gainesville, Florida 32610, USA.
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32
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Dou D, Zheng X, Liu J, Xu X, Ye L, Gao Y. Hydrogen peroxide enhances vasodilatation by increasing dimerization of cGMP-dependent protein kinase type Iα. Circ J 2012; 76:1792-8. [PMID: 22498562 DOI: 10.1253/circj.cj-11-1368] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
BACKGROUND cGMP-dependent protein kinase type I (PKG I) plays a key role in vasodilatation caused by cGMP-elevating agents. It is a homodimer in mammalian cells, existing as 2 isoforms, Iα and Iβ. The aim of the present study was both to determine whether PKG I dimerization and activity are modulated by hydrogen peroxide (H(2)O(2)) and its influence on vasodilatation. METHODS AND RESULTS The dimers and monomers of total PKG I and PKG Iβ were analyzed by Western blotting. PKG I activity was assayed by measuring the incorporation of (32)P into BPDEtide. Changes in vessels tension were determined by organ chamber technique. In isolated porcine coronary arteries, H(2)O(2) increased the dimers of total PKG I in a concentration-dependent manner, but had no effect on dimerization of PKG Iβ. The dimerization of PKG I caused by H(2)O(2) was prevented by catalase but not by deferoxamine and tiron. H(2)O(2) promoted the translocation of PKG I from cytoplasm to membrane. H(2)O(2) enhanced the activity of PKG I and relaxations of porcine coronary arteries to the nitric oxide donor and 8-Br-cGMP. Inhibition of catalase under in vivo conditions significantly decreased rat mean arterial pressure, which was associated with increased dimerization of PKG I. CONCLUSIONS The present study suggests that H(2)O(2) may enhance the activity of PKG Iα-and PKG I-dependent vasodilatation via increased dimerization of the enzyme.
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Affiliation(s)
- Dou Dou
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Peking University Health Science Center, Beijing, China
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Goto K, Kansui Y, Oniki H, Ohtsubo T, Matsumura K, Kitazono T. Upregulation of endothelium-derived hyperpolarizing factor compensates for the loss of nitric oxide in mesenteric arteries of dahl salt-sensitive hypertensive rats. Hypertens Res 2012; 35:849-54. [DOI: 10.1038/hr.2012.36] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
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Zhang DX, Borbouse L, Gebremedhin D, Mendoza SA, Zinkevich NS, Li R, Gutterman DD. H2O2-induced dilation in human coronary arterioles: role of protein kinase G dimerization and large-conductance Ca2+-activated K+ channel activation. Circ Res 2011; 110:471-80. [PMID: 22158710 DOI: 10.1161/circresaha.111.258871] [Citation(s) in RCA: 127] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
RATIONALE Hydrogen peroxide (H(2)O(2)) serves as a key endothelium-derived hyperpolarizing factor mediating flow-induced dilation in human coronary arterioles (HCAs). The precise mechanisms by which H(2)O(2) elicits smooth muscle hyperpolarization are not well understood. An important mode of action of H(2)O(2) involves the oxidation of cysteine residues in its target proteins, including protein kinase G (PKG)-Iα, thereby modulating their activities. OBJECTIVE Here we hypothesize that H(2)O(2) dilates HCAs through direct oxidation and activation of PKG-Iα leading to the opening of the large-conductance Ca(2+)-activated K(+) (BK(Ca)) channel and subsequent smooth muscle hyperpolarization. METHODS AND RESULTS Flow and H(2)O(2) induced pressure gradient/concentration-dependent vasodilation in isolated endothelium-intact and -denuded HCAs, respectively. The dilation was largely abolished by iberiotoxin, a BK(Ca) channel blocker. The PKG inhibitor Rp-8-Br-PET-cGMP also markedly inhibited flow- and H(2)O(2)-induced dilation, whereas the soluble guanylate cyclase inhibitor ODQ had no effect. Treatment of coronary smooth muscle cells (SMCs) with H(2)O(2) elicited dose-dependent, reversible dimerization of PKG-Iα, and induced its translocation to the plasma membrane. Patch-clamp analysis identified a paxilline-sensitive single-channel K(+) current with a unitary conductance of 246-pS in freshly isolated coronary SMCs. Addition of H(2)O(2) into the bath solution significantly increased the probability of BK(Ca) single-channel openings recorded from cell-attached patches, an effect that was blocked by the PKG-Iα inhibitor DT-2. H(2)O(2) exhibited an attenuated stimulatory effect on BK(Ca) channel open probability in inside-out membrane patches. CONCLUSIONS H(2)O(2) dilates HCAs through a novel mechanism involving protein dimerization and activation of PKG-Iα and subsequent opening of smooth muscle BK(Ca) channels.
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Affiliation(s)
- David X Zhang
- Department of Medicine, Cardiovascular Center, Medical College of Wisconsin, Milwaukee, 53226, USA.
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35
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Rocha JT, Hipólito UV, Callera GE, Yogi A, Neto Filho MDA, Bendhack LM, Touyz RM, Tirapelli CR. Ethanol induces vascular relaxation via redox-sensitive and nitric oxide-dependent pathways. Vascul Pharmacol 2011; 56:74-83. [PMID: 22155162 DOI: 10.1016/j.vph.2011.11.006] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2011] [Revised: 08/24/2011] [Accepted: 11/28/2011] [Indexed: 11/15/2022]
Abstract
We investigated the role of reactive oxygen species (ROS) and nitric oxide (NO) in ethanol-induced relaxation. Vascular reactivity experiments showed that ethanol (0.03-200 mmol/L) induced relaxation in endothelium-intact and denuded rat aortic rings isolated from male Wistar rats. Pre-incubation of intact or denuded rings with l-NAME (non selective NOS inhibitor, 100 μmol/L), 7-nitroindazole (selective nNOS inhibitor, 100 μmol/L), ODQ (selective inhibitor of guanylyl cyclase enzyme, 1 μmol/L), glibenclamide (selective blocker of ATP-sensitive K(+) channels, 3 μmol/L) and 4-aminopyridine (selective blocker of voltage-dependent K(+) channels, 4-AP, 1 mmol/L) reduced ethanol-induced relaxation. Similarly, tiron (superoxide anion (O(2)(-)) scavenger, 1 mmol/L) and catalase (hydrogen peroxide (H(2)O(2)) scavenger, 300 U/mL) reduced ethanol-induced relaxation to a similar extent in both endothelium-intact and denuded rings. Finally, prodifen (non-selective cytochrome P450 enzymes inhibitor, 10 μmol/L) and 4-methylpyrazole (selective alcohol dehydrogenase inhibitor, 10 μmol/L) reduced ethanol-induced relaxation. In cultured aortic vascular smooth muscle cells (VSMCs), ethanol stimulated generation of NO, which was significantly inhibited by l-NAME. In endothelial cells, flow cytometry studies showed that ethanol increased cytosolic Ca(2+) concentration ([Ca(2+)]c), O(2)(-) and cytosolic NO concentration ([NO]c). Tiron inhibited ethanol-induced increase in [Ca(2+)]c and [NO]c. The major new finding of this work is that ethanol induces relaxation via redox-sensitive and NO-cGMP-dependent pathways through direct effects on ROS production and NO signaling. These findings identify putative molecular mechanisms whereby ethanol, at pharmacological concentrations, influences vascular reactivity.
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MESH Headings
- Animals
- Aorta/drug effects
- Aorta/metabolism
- Cells, Cultured
- Cyclic GMP/metabolism
- Endothelial Cells/drug effects
- Endothelial Cells/metabolism
- Endothelium, Vascular/drug effects
- Endothelium, Vascular/metabolism
- Ethanol/pharmacology
- Male
- Muscle, Smooth, Vascular/drug effects
- Muscle, Smooth, Vascular/metabolism
- Myocytes, Smooth Muscle/drug effects
- Myocytes, Smooth Muscle/metabolism
- Nitric Oxide/metabolism
- Oxidation-Reduction
- Rats
- Rats, Wistar
- Reactive Oxygen Species/metabolism
- Signal Transduction/drug effects
- Vasodilation/drug effects
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Affiliation(s)
- Juliana T Rocha
- Department of Psychiatric Nursing and Human Sciences, Laboratory of Pharmacology, College of Nursing of Ribeirão Preto, University of São Paulo, Ribeirão Preto, SP, Brazil
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Ozkor MA, Quyyumi AA. Endothelium-derived hyperpolarizing factor and vascular function. Cardiol Res Pract 2011; 2011:156146. [PMID: 21876822 PMCID: PMC3157651 DOI: 10.4061/2011/156146] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/07/2011] [Revised: 05/27/2011] [Accepted: 05/27/2011] [Indexed: 01/20/2023] Open
Abstract
Endothelial function refers to a multitude of physiological processes that maintain healthy homeostasis of the vascular wall. Exposure of the endothelium to cardiac risk factors results in endothelial dysfunction and is associated with an alteration in the balance of vasoactive substances produced by endothelial cells. These include a reduction in nitric oxide (NO), an increase in generation of potential vasoconstrictor substances and a potential compensatory increase in other mediators of vasodilation. The latter has been surmised from data demonstrating persistent endothelium-dependent vasodilatation despite complete inhibition of NO and prostaglandins. This remaining non-NO, non-prostaglandin mediated endothelium-dependent vasodilator response has been attributed to endothelium-derived hyperpolarizing factor/s (EDHF). Endothelial hyperpolarization is likely due to several factors that appear to be site and species specific. Experimental studies suggest that the contribution of the EDHFs increase as the vessel size decreases, with a predominance of EDHF activity in the resistance vessels, and a compensatory up-regulation of hyperpolarization in states characterized by reduced NO availability. Since endothelial dysfunction is a precursor for atherosclerosis development and its magnitude is a reflection of future risk, then the mechanisms underlying endothelial dysfunction need to be fully understood, so that adequate therapeutic interventions can be designed.
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Affiliation(s)
- Muhiddin A Ozkor
- The Heart Hospital, University College London, London WIG 8PH, UK
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Qi M, Hang C, Zhu L, Shi J. Involvement of endothelial-derived relaxing factors in the regulation of cerebral blood flow. Neurol Sci 2011; 32:551-7. [PMID: 21584736 DOI: 10.1007/s10072-011-0622-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2011] [Accepted: 05/05/2011] [Indexed: 11/30/2022]
Abstract
Despite numerous researches and advances in the present times, delayed cerebral vasospasm remains a severe complication leading to a high mortality and morbidity in patients with subarachnoid hemorrhage (SAH). Since the discovery of endothelium-derived relaxing factor (EDRF) in 1980, its role in delayed cerebral vasospasm after SAH has been widely investigated as well as in regulation of basic cerebral blood flow, pathophysiology of vasoconstriction and application on prevention and treatment of cerebral vasospasm. Among all the EDRFs, nitric oxide has caught the most attention, and the other substances which display similar properties with characteristics of EDRF such as carbon monoxide (CO), hydrogen sulfide (H(2)S), hydrogen peroxide (H(2)O(2)), potassium ion (K(+)) and methane (CH(4)) have also evoked great interest in the research field. This review provides an overview of recent advances in investigations on the involvement of EDRFs in the regulation of cerebral blood flow, especially in cerebral vasospasm after SAH. Possible therapeutic measures and potential clinical implications for cerebral vasospasm are also summarized.
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Affiliation(s)
- Meng Qi
- Department of Neurosurgery, Jinling Hospital, Nanjing University Medical School, Nanjing, 210002, Jiangsu, China.
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38
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Liu B, Sun X, Zhu Y, Gan L, Xu H, Yang X. Biphasic effects of H(2)O(2) on BK(Ca) channels. Free Radic Res 2011; 44:1004-12. [PMID: 20560834 DOI: 10.3109/10715762.2010.495126] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
The inhibitory or activating effect of H(2)O(2) on large conductance calcium and voltage-dependent potassium (BK(Ca)) channels has been reported. However, the mechanism by which this occurs is unclear. In this paper, BK(Ca) channels encoded by mouse Slo were expressed in HEK 293 cells and BK(Ca) channel activity was measured by electrophysiology. The results showed that H(2)O(2) inhibited BK(Ca) channel activity in inside-out patches but enhanced BK(Ca) channel activity in cell-attached patches. The inhibition by H(2)O(2) in inside-out patches may be due to oxidative modification of cysteine residues in BK(Ca) channels or other membrane proteins that regulate BK(Ca) channel function. PI3K/AKT signaling modulates the H(2)O(2)-induced BK(Ca) channel activation in cell-attached patches. BK(Ca) channels and PI3K signaling pathway were involved in H(2)O(2)-induced vasodilation and H(2)O(2)-induced vasodilation by PI3K pathway was mainly due to modulation of BK(Ca) channel activity.
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Affiliation(s)
- Bo Liu
- Huazhong University of Science and Technology, Wuhan, PR China
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39
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Liu Y, Bubolz AH, Mendoza S, Zhang DX, Gutterman DD. H2O2 is the transferrable factor mediating flow-induced dilation in human coronary arterioles. Circ Res 2011; 108:566-73. [PMID: 21233456 DOI: 10.1161/circresaha.110.237636] [Citation(s) in RCA: 140] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
RATIONALE Endothelial derived hydrogen peroxide (H(2)O(2)) is a necessary component of the pathway regulating flow-mediated dilation (FMD) in human coronary arterioles (HCAs). However, H(2)O(2) has never been shown to be the endothelium-dependent transferrable hyperpolarization factor (EDHF) in response to shear stress. OBJECTIVE We examined the hypothesis that H(2)O(2) serves as the EDHF in HCAs to shear stress. METHODS AND RESULTS Two HCAs were cannulated in series (a donor intact vessel upstream and endothelium-denuded detector vessel downstream). Diameter changes to flow were examined in the absence and presence of polyethylene glycol catalase (PEG-CAT). The open state probability of large conductance Ca(2+)-activated K(+) (BK(Ca)) channels in smooth muscle cells downstream from the perfusate from an endothelium-intact arteriole was examined by patch clamping. In some experiments, a cyanogen bromide-activated resin column bound with CAT was used to remove H(2)O(2) from the donor vessel. When flow proceeds from donor to detector, both vessels dilate (donor:68±7%; detector: 45±11%). With flow in the opposite direction, only the donor vessel dilates. PEG-CAT contacting only the detector vessel blocked FMD in that vessel (6±4%) but not in donor vessel (61±13%). Paxilline inhibited dilation of endothelium-denuded HCAs to H(2)O(2). Effluent from donor vessels elicited K(+) channel opening in an iberiotoxin- or PEG-CAT-sensitive fashion in cell-attached patches but had little effect on channel opening on inside-out patches. Vasodilation of detector vessels was diminished when exposed to effluent from CAT-column. CONCLUSIONS Flow induced endothelial production of H(2)O(2), which acts as the transferrable EDHF activating BK(Ca) channels on the smooth muscle cells.
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Affiliation(s)
- Yanping Liu
- Office of Research, Medical College of Wisconsin, 8701 Watertown Plank Rd, Milwaukee, WI 53226, USA
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40
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Snetkov VA, Smirnov SV, Kua J, Aaronson PI, Ward JPT, Knock GA. Superoxide differentially controls pulmonary and systemic vascular tone through multiple signalling pathways. Cardiovasc Res 2010; 89:214-24. [PMID: 20805095 PMCID: PMC3002873 DOI: 10.1093/cvr/cvq275] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Aims The aim of this study was to determine the relative importance of Ca2+ sensitization, ion channels, and intracellular Ca2+ ([Ca2+]i) in the mixed constrictor/relaxation actions of superoxide anion on systemic and pulmonary arteries. Methods and results Pulmonary and mesenteric arteries were obtained from rat. Superoxide was generated in arteries and cells with 6-anilino-5,8-quinolinequinone (LY83583). Following pre-constriction with U46619, 10 μmol/L LY83583 caused constriction in pulmonary and relaxation in mesenteric arteries. Both constrictor and relaxant actions of LY83583 were inhibited by superoxide dismutase and catalase. LY83583 caused Rho-kinase-dependent constriction in α-toxin-permeabilized pulmonary but not mesenteric arteries. Phosphorylation of myosin phosphatase-targeting subunit-1 (MYPT-1; as determined by western blot), was enhanced by LY83583 in pulmonary artery only. However, in both artery types, changes in tension were closely correlated with changes in phosphorylation of the 20 kDa myosin light chain as well as changes in [Ca2+]i (as measured with Fura PE-3), with LY83583 causing increases in pulmonary and decreases in mesenteric arteries. When U46619 was replaced by 30 mmol/L K+, all changes in [Ca2+]i were abolished and LY83583 constricted both artery types. The KV channel inhibitor 4-aminopyridine abolished the LY83583-induced relaxation in mesenteric artery without affecting constriction in pulmonary artery. However, LY83583 caused a similar hyperpolarizing shift in the steady-state activation of KV current in isolated smooth muscle cells of both artery types. Conclusions Superoxide only causes Rho-kinase-dependent Ca2+ sensitization in pulmonary artery, resulting in constriction, and whilst it opens KV channels in both artery types, this only results in relaxation in mesenteric.
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Affiliation(s)
- Vladimir A Snetkov
- Division of Asthma, Allergy and Lung Biology, School of Medicine, King's College London, Room 3.20, Franklin Wilkins Building, Stamford Street, London SE1 9NH, UK
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Relative contribution of eNOS and nNOS to endothelium-dependent vasodilation in the mouse aorta. Eur J Pharmacol 2010; 643:260-6. [PMID: 20624383 DOI: 10.1016/j.ejphar.2010.06.066] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2010] [Revised: 06/07/2010] [Accepted: 06/24/2010] [Indexed: 11/22/2022]
Abstract
In large vessels, endothelium-dependent vasodilation is mainly attributed to endothelial nitric oxide synthase (eNOS)-derived NO production. However, we have recently shown that neuronal nitric oxide synthase (nNOS)-derived H(2)O(2) is also an endothelium-dependent relaxing factor in the mouse aorta. The relative contribution of nNOS/eNOS, H(2)O(2)/NO remains to be characterized. This work was undertaken to determine the relative contribution of NO versus H(2)O(2), and eNOS versus nNOS to endothelium-dependent vasodilation in the mouse aorta. We used carbon microsensors placed next to the lumen of the vessels to simultaneously measure NO, H(2)O(2) and vascular tone. Acetylcholine produced a concentration-dependent increase in NO and H(2)O(2) production with a good coefficient of linearity with acetylcholine-induced relaxation (R(2)=0.93 and 0.96 for NO and H(2)O(2), respectively). L-NAME, a non-selective inhibitor of nitric oxide synthase, abolished NO and H(2)O(2) production, and impaired vasodilation. Selective pharmacological inhibition of nNOS with L-Arg(NO2)-L-Dbu-NH(2) 2TFA and specific knock-down of nNOS abrogated H(2)O(2) and decreased by half acetylcholine-induced vasodilation. Catalase, which specifically decomposes H(2)O(2), did not interfere with NO, but impaired H(2)O(2) and decreased vasodilation to the same level as those obtained with nNOS inhibition or knocking down. Specific knocking down of eNOS had no effect on H(2)O(2) production but greatly reduced NO and decreased vasodilation to levels similar to those found with nNOS inhibition. In eNOS knocked-down mice, pharmacological nNOS inhibition dramatically reduced H(2)O(2) production and further reduced the residual acetylcholine-induced vasodilation. It is concluded that nNOS/eNOS and H(2)O(2)/NO both contribute in a significant way to relaxation in the mouse aorta.
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42
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Hydrogen peroxide as an endothelium-derived hyperpolarizing factor. Pflugers Arch 2010; 459:915-22. [PMID: 20140449 DOI: 10.1007/s00424-010-0790-8] [Citation(s) in RCA: 88] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2009] [Revised: 01/08/2010] [Accepted: 01/13/2010] [Indexed: 10/19/2022]
Abstract
The endothelium plays an important role in maintaining cardiovascular homeostasis by synthesizing and releasing several vasodilating substances, including vasodilator prostaglandins, nitric oxide (NO), and endothelium-derived hyperpolarizing factor (EDHF). Since the first report on the existence of EDHF, several substances/mechanisms have been proposed for the nature of EDHF, including epoxyeicosatrienoic acids (metabolites of arachidonic P450 epoxygenase pathway), K ions, and electrical communications through myoendothelial gap junctions. We have demonstrated that endothelium-derived hydrogen peroxide (H(2)O(2)) is an EDHF in animals and humans. For the synthesis of H(2)O(2)/EDHF, endothelial NO synthase system that is functionally coupled with Cu,Zn-superoxide dismutase plays a crucial role. Importantly, endothelium-derived H(2)O(2) plays important protective roles in the coronary circulation, including coronary autoregulation, protection against myocardial ischemia/reperfusion injury, and metabolic coronary vasodilatation. Indeed, our H(2)O(2)/EDHF theory demonstrates that endothelium-derived H(2)O(2), another reactive oxygen species in addition to NO, plays important roles as a redox-signaling molecule to cause vasodilatation as well as cardioprotection. In this review, we summarize our current knowledge on H(2)O(2)/EDHF regarding its identification and mechanisms of synthesis and actions.
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Gao Y, Yang Y, Guan Q, Pang X, Zhang H, Zeng D. IL-1beta modulate the Ca(2+)-activated big-conductance K channels (BK) via reactive oxygen species in cultured rat aorta smooth muscle cells. Mol Cell Biochem 2009; 338:59-68. [PMID: 19949838 DOI: 10.1007/s11010-009-0338-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2009] [Accepted: 11/19/2009] [Indexed: 10/20/2022]
Abstract
The large conductance Ca(2+)-activated K(+) (BK) channel, abundantly expressed in vascular smooth muscle cells, plays a critical role in controlling vascular tone. Activation of BK channels leads to membrane hyperpolarization and promotes vasorelaxation. BK channels are activated either by elevation of the intracellular Ca(2+) concentration or by membrane depolarization. It is also regulated by a diversity of vasodilators and vasoconstrictors. Interleukin-1beta (IL-1beta) is one of the cytokines that play important roles in the development and progression of a variety of cardiovascular diseases. The effects of IL-1beta on vascular reactivity are controversial, and little is known about the modulation of BK channel function by IL-1beta. In this study, we investigated how IL-1beta modulates BK channel function in cultured arterial smooth muscle cells (ASMCs), and examined the role of H(2)O(2) in the process. We demonstrated that IL-1beta had biphasic effects on BK channel function and membrane potential of ASMCs, that is both concentration and time dependent. IL-1beta increased BK channel-dependent K(+) current and hyperpolarized ASMCs when applied for 30 min. While long-term (24-48 h) treatment of IL-1beta resulted in decreased expression of alpha-subunit of BK channel, suppressed BK channel activity, decreased BK channel-dependent K(+) current and depolarization of the cells. H(2)O(2) scavenger catalase completely abolished the early effect of IL-1beta, while it only partly diminished the long-term effect of IL-1beta. These results may provide important molecular mechanisms for therapeutic strategies targeting BK channel in inflammation-related diseases.
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Affiliation(s)
- Yuan Gao
- Department of Cardiology, the First Affiliated Hospital, China Medical University, Heping District, Shengyang, People's Republic of China
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44
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Kumar S, Sud N, Fonseca FV, Hou Y, Black SM. Shear stress stimulates nitric oxide signaling in pulmonary arterial endothelial cells via a reduction in catalase activity: role of protein kinase C delta. Am J Physiol Lung Cell Mol Physiol 2009; 298:L105-16. [PMID: 19897742 DOI: 10.1152/ajplung.00290.2009] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Previous studies have indicated that acute increases in shear stress can stimulate endothelial nitric oxide synthase (eNOS) activity through increased PI3 kinase/Akt signaling and phosphorylation of Ser1177. However, the mechanism by which shear stress activates this pathway has not been adequately resolved nor has the potential role of reactive oxygen species (ROS) been evaluated. Thus, the purpose of this study was to determine if shear-mediated increases in ROS play a role in stimulating Ser1177 phosphorylation and NO signaling in pulmonary arterial endothelial cells (PAEC) exposed to acute increases in shear stress. Our initial studies demonstrated that although shear stress did not increase superoxide levels in PAEC, there was an increase in H2O2 levels. The increases in H2O2 were associated with a decrease in catalase activity but not protein levels. In addition, we found that acute shear stress caused an increase in eNOS phosphorylation at Ser1177 phosphorylation and a decrease in phosphorylation at Thr495. We also found that the overexpression of catalase significantly attenuated the shear-mediated increases in H2O2, phospho-Ser1177 eNOS, and NO generation. Further investigation identified a decrease in PKCdelta activity in response to shear stress, and the overexpression of PKCdelta attenuated the shear-mediated decrease in Thr495 phosphorylation and the increase in NO generation, and this led to increased eNOS uncoupling. PKCdelta overexpression also attenuated Ser1177 phosphorylation through a posttranslational increase in catalase activity, mediated via a serine phosphorylation event, reducing shear-mediated increases in H2O2. Together, our data indicate that shear stress decreases PKCdelta activity, altering the phosphorylation pattern catalase, leading to decreased catalase activity and increased H2O2 signaling, and this in turn leads to increases in phosphorylation of eNOS at Ser1177 and NO generation.
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Affiliation(s)
- Sanjiv Kumar
- Vascular Biology Center: CB-3210B, Medical College of Georgia, 1459 Laney Walker Blvd., Augusta, GA 30912, USA
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45
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Liu B, Gan L, Sun X, Zhu Y, Tong Z, Xu H, Yang X. Enhancement of BK(Ca) channel activity induced by hydrogen peroxide: involvement of lipid phosphatase activity of PTEN. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2009; 1788:2174-82. [PMID: 19646416 DOI: 10.1016/j.bbamem.2009.07.016] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/27/2009] [Revised: 07/01/2009] [Accepted: 07/22/2009] [Indexed: 02/06/2023]
Abstract
Large-conductance calcium and voltage-dependent potassium (BK(Ca)) channel is an important determinant of vascular tone. It is activated by hydrogen peroxide (H(2)O(2)) which occurs in various physiological and pathological processes. However, the regulation mechanism is not fully understood. In the present study, the mSlo in the presence or absence of hbeta1 were cotransfected with the PTEN(wt), PTEN(C124S), PTEN(G129E) in HEK 293 cells. Typical BK(Ca) channel currents could be recorded in cell-attached configurations. We found that PTEN(wt) reduced the H(2)O(2)-induced BK(Ca) channel activation during the initial 10 min treatment. In contrast, coexpression with catalytically inactive PTEN(C124S)/PTEN(G129E) mutants that lack lipid phosphatase activity produced no regulation on the H(2)O(2)-induced BK(Ca) channel activation. These results demonstrated that PTEN regulated the H(2)O(2)-induced BK(Ca) channel activation through phosphatidylinositol 3-phosphatse. However, the inhibitory effect of PTEN on the H(2)O(2)-induced BK(Ca) channel activation was attenuated when cells were treated with H(2)O(2) at concentrations higher than 100 microM or at 100 microM for long-term treatment. In addition, the p-AKT expression level in PTEN(wt) overexpressing cells was lower than that in control cells, and the increase of cytoplasmic free calcium concentration ([Ca(2+)](i)) induced by H(2)O(2) was also inhibited. These findings may elucidate a new mechanism for H(2)O(2)-induced BK(Ca) channel activation and provide some evidences for the role of PTEN on vasodilation induced by H(2)O(2).
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Affiliation(s)
- Bo Liu
- College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, 430074, China
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46
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Ellis A, Goto K, Chaston DJ, Brackenbury TD, Meaney KR, Falck JR, Wojcikiewicz RJH, Hill CE. Enalapril treatment alters the contribution of epoxyeicosatrienoic acids but not gap junctions to endothelium-derived hyperpolarizing factor activity in mesenteric arteries of spontaneously hypertensive rats. J Pharmacol Exp Ther 2009; 330:413-22. [PMID: 19411610 DOI: 10.1124/jpet.109.152116] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Reduction in endothelium-derived hyperpolarizing factor (EDHF)-mediated dilatory function in large, elastic arteries during hypertension is reversed after blood pressure normalization. We investigated whether similar mechanisms occurred in smaller mesenteric resistance arteries from aged Wistar-Kyoto (WKY) rats, spontaneously hypertensive rats (SHRs), and SHRs treated with the angiotensin-converting enzyme inhibitor, enalapril, using immunohistochemistry, serial-section electron microscopy, electrophysiology and wire myography. Unlike the superior mesenteric artery, EDHF relaxations in muscular mesenteric arteries were not reduced in SHRs, although morphological differences were found in the endothelium and smooth muscle. In WKY rats, SHRs and enalapril-treated SHRs, relaxations were mediated by small-, large-, and intermediate-conductance calcium-activated potassium channels, which were distributed in the endothelium, smooth muscle, and both layers, respectively. However, only WKY hyperpolarizations and relaxations were sensitive to gap junction blockers, and these arteries expressed more endothelial and myoendothelial gap junctions than arteries from SHRs. Responses in WKY rats, but not SHRs, were also reduced by inhibitors of epoxyeicosatrienoic acids (EETs), 14,15-epoxyeicosa-5(Z)-enoic acid (14,15-EEZE) and miconazole, although sensitivity to EET regioisomers was endothelium-independent in all rats. Enalapril treatment of SHRs reduced blood pressure and restored sensitivity to 14,15-EEZE, but not to gap junction blockers, and failed to reverse the morphological changes. In conclusion, the mechanisms underlying EDHF in muscular mesenteric arteries differ between WKY rats and SHRs, with gap junctions and EETs involved only in WKY rats. However, reduction of blood pressure in SHRs with enalapril restored a role for EETs, but not gap junctions, without reversing morphological changes, suggesting a differential control of chemical and structural alterations.
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Affiliation(s)
- Anthie Ellis
- Division of Neuroscience, John Curtin School of Medical Research, Australian National University, Canberra ACT 0200, Australia
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47
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Garrido AM, Griendling KK. NADPH oxidases and angiotensin II receptor signaling. Mol Cell Endocrinol 2009; 302:148-58. [PMID: 19059306 PMCID: PMC2835147 DOI: 10.1016/j.mce.2008.11.003] [Citation(s) in RCA: 287] [Impact Index Per Article: 19.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/26/2008] [Revised: 10/17/2008] [Accepted: 11/03/2008] [Indexed: 02/07/2023]
Abstract
Over the last decade many studies have demonstrated the importance of reactive oxygen species (ROS) production by NADPH oxidases in angiotensin II (Ang II) signaling, as well as a role for ROS in the development of different diseases in which Ang II is a central component. In this review, we summarize the mechanism of activation of NADPH oxidases by Ang II and describe the molecular targets of ROS in Ang II signaling in the vasculature, kidney and brain. We also discuss the effects of genetic manipulation of NADPH oxidase function on the physiology and pathophysiology of the renin-angiotensin system.
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48
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Hou S, Heinemann SH, Hoshi T. Modulation of BKCa channel gating by endogenous signaling molecules. Physiology (Bethesda) 2009; 24:26-35. [PMID: 19196649 DOI: 10.1152/physiol.00032.2008] [Citation(s) in RCA: 109] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Large-conductance Ca(2+)- and voltage-activated K(+) (BK(Ca), MaxiK, or Slo1) channels are expressed in almost every tissue in our body and participate in many critical functions such as neuronal excitability, vascular tone regulation, and neurotransmitter release. The functional versatility of BK(Ca) channels owes in part to the availability of a spectacularly wide array of biological modulators of the channel function. In this review, we focus on modulation of BK(Ca) channels by small endogenous molecules, emphasizing their molecular mechanisms. The mechanistic information available from studies on the small naturally occurring modulators is expected to contribute to our understanding of the physiological and pathophysiological roles of BK(Ca) channels.
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Affiliation(s)
- Shangwei Hou
- Department of Physiology, University of Pennsylvania, Philadelphia, Pennsylvania, USA
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49
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Capettini LSA, Cortes SF, Gomes MA, Silva GAB, Pesquero JL, Lopes MJ, Teixeira MM, Lemos VS. Neuronal nitric oxide synthase-derived hydrogen peroxide is a major endothelium-dependent relaxing factor. Am J Physiol Heart Circ Physiol 2008; 295:H2503-11. [PMID: 18952716 DOI: 10.1152/ajpheart.00731.2008] [Citation(s) in RCA: 75] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Endothelium-dependent vasorelaxation in large vessels is mainly attributed to Nomega-nitro-L-arginine methyl ester (L-NAME)-sensitive endothelial nitric oxide (NO) synthase (eNOS)-derived NO production. Endothelium-derived hyperpolarizing factor (EDHF) is the component of endothelium-dependent relaxations that resists full blockade of NO synthases (NOS) and cyclooxygenases. H2O2 has been proposed as an EDHF in resistance vessels. In this work we propose that in mice aorta neuronal (n)NOS-derived H2O2 accounts for a large proportion of endothelium-dependent ACh-induced relaxation. In mice aorta rings, ACh-induced relaxation was inhibited by L-NAME and Nomega-nitro-L-arginine (L-NNA), two nonselective inhibitors of NOS, and attenuated by selective inhibition of nNOS with L-ArgNO2-L-Dbu-NH2 2TFA (L-ArgNO2-L-Dbu) and 1-(2-trifluoromethylphehyl)imidazole (TRIM). The relaxation induced by ACh was associated with enhanced H2O2 production in endothelial cells that was prevented by the addition of L-NAME, L-NNA, L-ArgNO2-L-Dbu, TRIM, and removal of the endothelium. The addition of catalase, an enzyme that degrades H2O2, reduced ACh-dependent relaxation and abolished ACh-induced H2O2 production. RT-PCR experiments showed the presence of mRNA for eNOS and nNOS but not inducible NOS in mice aorta. The constitutive expression of nNOS was confirmed by Western blot analysis in endothelium-containing vessels but not in endothelium-denuded vessels. Immunohistochemistry data confirmed the localization of nNOS in the vascular endothelium. Antisense knockdown of nNOS decreased both ACh-dependent relaxation and ACh-induced H2O2 production. Antisense knockdown of eNOS decreased ACh-induced relaxation but not H2O2 production. Residual relaxation in eNOS knockdown mouse aorta was further inhibited by the selective inhibition of nNOS with L-ArgNO2-L-Dbu. In conclusion, these results show that nNOS is constitutively expressed in the endothelium of mouse aorta and that nNOS-derived H2O2 is a major endothelium-dependent relaxing factor. Hence, in the mouse aorta, the effects of nonselective NOS inhibitors cannot be solely ascribed to NO release and action without considering the coparticipation of H2O2 in mediating vasodilatation.
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Affiliation(s)
- L S A Capettini
- Department of Physiology and Biophysics, ICB, Federal University of Minas Gerais. Av. Antônio Carlos, 6627, Pampulha 31270-901, Belo Horizonte, MG, Brazil
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50
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Dong DL, Yue P, Yang BF, Wang WH. Hydrogen peroxide stimulates the Ca(2+)-activated big-conductance K channels (BK) through cGMP signaling pathway in cultured human endothelial cells. Cell Physiol Biochem 2008; 22:119-26. [PMID: 18769038 DOI: 10.1159/000149789] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/17/2008] [Indexed: 01/22/2023] Open
Abstract
We used the whole cell patch-clamp technique to examine the effect of hydrogen peroxide (H(2)O(2)) on the Ca2(+)-activated BK channels in human endothelial cells. We confirmed the previous finding that a 200 pS BK channel activity was detected when the cell membrane potential was clamped at 50 mV. Application of H(2)O(2) or adding glucose oxidase (GO) stimulated BK channels. The stimulatory effect of H(2)O(2) and GO was absent in cells treated with ebselen, a scavenger of reactive oxygen species (ROS). To determine whether the stimulatory effect of H(2)O(2) and GO on BK channels is the result of increasing NO production in the endothelial cells, we examined the effect of H(2)O(2) and GO on BK channels in the presence of 0.1 mM L-NAME which inhibits NO synthase (NOS). Inhibition of NOS completely abolished the stimulatory effect of H(2)O(2) on BK channels. In contrast, treatment of endothelial cells with D-NAME did not block the effect of H(2)O(2) on BK channels. Moreover, inhibiting soluble guanylate cyclase (sGC) with ODQ mimicked the effect of L-NAME and abolished the effect of H(2)O(2). Addition of 8-bromo-cGMP stimulated BK channels and further application of H(2)O(2) did not increase BK channel activity in the presence of cGMP analog. The notion that the effect of H(2)O(2) on BK channels was the result of stimulating NO-cGMP pathway is further indicated by the observation that inhibition of PKG with KT5823 also abolished the stimulatory effect of H(2)O(2) on BK channels. We conclude that H(2)O(2) stimulates the Ca2(+) BK channels through NO/sGC/cGMP pathway in cultured human endothelial cells.
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Affiliation(s)
- De-Li Dong
- Department of Pharmacology, Harbin Medical University
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