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Chopoorian AH, Wahba A, Celedonio J, Nwazue V, Smith EC, Garland EM, Paranjape S, Okamoto LE, Black BK, Biaggioni I, Raj SR, Gamboa A. Impaired Endothelial Function in Patients With Postural Tachycardia Syndrome. Hypertension 2021; 77:1001-1009. [PMID: 33486983 DOI: 10.1161/hypertensionaha.120.16238] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
The purpose of this study is to evaluate endothelial function in postural tachycardia syndrome (PoTS), a poorly understood chronic condition characterized by a state of consistent orthostatic tachycardia (delta heart rate ≥30 beats per minute) upon standing without orthostatic hypotension. Nineteen patients with PoTS and 9 healthy controls were studied after 3 days of a fixed, caffeine-free, normal sodium (150 milliequivalents/day) diet. All participants underwent autonomic function testing, including sinus arrhythmia, valsalva maneuver, hyperventilation, cold pressor, handgrip, and a standing test with catecholamine measurements, followed by endothelial function testing. We analyzed 3 measures of endothelial function: percent brachial flow-mediated dilation, digital pulsatile arterial tonometry, and postischemic percent leg blood flow. Flow-mediated dilation was significantly lower in patients with PoTS (6.23±3.54% for PoTS) than in healthy controls (10.6±4.37% for controls versus, P=0.014). PoTS and controls had similar digital pulsatile arterial tonometry (1.93±0.40 arbitrary units for controls versus 2.13±0.63 arbitrary units for PoTS). PoTS had similar but suggestive percent leg blood flow to controls (313±158% for PoTS versus 468±236% for controls, P=0.098). Patients with PoTS have significantly reduced flow-mediated dilation compared with healthy controls, suggesting that PoTS is characterized by endothelial dysfunction in conduit arteries. Registration: URL: https://www.clinicaltrials.gov. Unique identifier: NCT01308099.
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Affiliation(s)
- Abby H Chopoorian
- From the Vanderbilt University School of Medicine (A.H.C.), Vanderbilt University Medical Center, Nashville, TN
| | - Amr Wahba
- Vanderbilt Autonomic Dysfunction Center, Division of Clinical Pharmacology, Department of Medicine (A.W., J.C., V.N., E.C.S., E.M.G., S.P., L.E.O., B.K.B., I.B., A.G.), Vanderbilt University Medical Center, Nashville, TN
| | - Jorge Celedonio
- Vanderbilt Autonomic Dysfunction Center, Division of Clinical Pharmacology, Department of Medicine (A.W., J.C., V.N., E.C.S., E.M.G., S.P., L.E.O., B.K.B., I.B., A.G.), Vanderbilt University Medical Center, Nashville, TN
| | - Victor Nwazue
- Vanderbilt Autonomic Dysfunction Center, Division of Clinical Pharmacology, Department of Medicine (A.W., J.C., V.N., E.C.S., E.M.G., S.P., L.E.O., B.K.B., I.B., A.G.), Vanderbilt University Medical Center, Nashville, TN
| | - Emily C Smith
- Vanderbilt Autonomic Dysfunction Center, Division of Clinical Pharmacology, Department of Medicine (A.W., J.C., V.N., E.C.S., E.M.G., S.P., L.E.O., B.K.B., I.B., A.G.), Vanderbilt University Medical Center, Nashville, TN
| | - Emily M Garland
- Vanderbilt Autonomic Dysfunction Center, Division of Clinical Pharmacology, Department of Medicine (A.W., J.C., V.N., E.C.S., E.M.G., S.P., L.E.O., B.K.B., I.B., A.G.), Vanderbilt University Medical Center, Nashville, TN
| | - Sachin Paranjape
- Vanderbilt Autonomic Dysfunction Center, Division of Clinical Pharmacology, Department of Medicine (A.W., J.C., V.N., E.C.S., E.M.G., S.P., L.E.O., B.K.B., I.B., A.G.), Vanderbilt University Medical Center, Nashville, TN
| | - Luis E Okamoto
- Vanderbilt Autonomic Dysfunction Center, Division of Clinical Pharmacology, Department of Medicine (A.W., J.C., V.N., E.C.S., E.M.G., S.P., L.E.O., B.K.B., I.B., A.G.), Vanderbilt University Medical Center, Nashville, TN
| | - Bonnie K Black
- Vanderbilt Autonomic Dysfunction Center, Division of Clinical Pharmacology, Department of Medicine (A.W., J.C., V.N., E.C.S., E.M.G., S.P., L.E.O., B.K.B., I.B., A.G.), Vanderbilt University Medical Center, Nashville, TN
| | - Italo Biaggioni
- Vanderbilt Autonomic Dysfunction Center, Division of Clinical Pharmacology, Department of Medicine (A.W., J.C., V.N., E.C.S., E.M.G., S.P., L.E.O., B.K.B., I.B., A.G.), Vanderbilt University Medical Center, Nashville, TN.,Department of Pharmacology, Vanderbilt University, Nashville, TN (I.B.)
| | - Satish R Raj
- Department of Cardiac Sciences, Libin Cardiovascular Institute, Cumming School of Medicine, University of Calgary, Alberta, Canada (S.R.R.)
| | - Alfredo Gamboa
- Vanderbilt Autonomic Dysfunction Center, Division of Clinical Pharmacology, Department of Medicine (A.W., J.C., V.N., E.C.S., E.M.G., S.P., L.E.O., B.K.B., I.B., A.G.), Vanderbilt University Medical Center, Nashville, TN
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Szarka N, Pabbidi MR, Amrein K, Czeiter E, Berta G, Pohoczky K, Helyes Z, Ungvari Z, Koller A, Buki A, Toth P. Traumatic Brain Injury Impairs Myogenic Constriction of Cerebral Arteries: Role of Mitochondria-Derived H 2O 2 and TRPV4-Dependent Activation of BK ca Channels. J Neurotrauma 2018; 35:930-939. [PMID: 29179622 DOI: 10.1089/neu.2017.5056] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Traumatic brain injury (TBI) impairs autoregulation of cerebral blood flow, which contributes to the development of secondary brain injury, increasing mortality of patients. Impairment of pressure-induced myogenic constriction of cerebral arteries plays a critical role in autoregulatory dysfunction; however, the underlying cellular and molecular mechanisms are not well understood. To determine the role of mitochondria-derived H2O2 and large-conductance calcium-activated potassium channels (BKCa) in myogenic autoregulatory dysfunction, middle cerebral arteries (MCAs) were isolated from rats with severe weight drop-impact acceleration brain injury. We found that 24 h post-TBI MCAs exhibited impaired myogenic constriction, which was restored by treatment with a mitochondria-targeted antioxidant (mitoTEMPO), by scavenging of H2O2 (polyethylene glycol [PEG]-catalase) and by blocking both BKCa channels (paxilline) and transient receptor potential cation channel subfamily V member 4 (TRPV4) channels (HC 067047). Further, exogenous administration of H2O2 elicited significant dilation of MCAs, which was inhibited by blocking either BKCa or TRPV4 channels. Vasodilation induced by the TRPV4 agonist GSK1016790A was inhibited by paxilline. In cultured vascular smooth muscle cells H2O2 activated BKCa currents, which were inhibited by blockade of TRPV4 channels. Collectively, our results suggest that after TBI, excessive mitochondria-derived H2O2 activates BKCa channels via a TRPV4-dependent pathway in the vascular smooth muscle cells, which impairs pressure-induced constriction of cerebral arteries. Future studies should elucidate the therapeutic potential of pharmacological targeting of this pathway in TBI, to restore autoregulatory function in order to prevent secondary brain damage and decrease mortality.
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Affiliation(s)
- Nikolett Szarka
- Cerebrovascular Laboratory, Department of Neurosurgery, Medical School University of Pecs, Pecs. Hungary.,Neurotrauma Research Group, Janos Szentagothai Research Center, Medical School University of Pecs, Pecs. Hungary.,Department of Translational Medicine, Medical School University of Pecs, Pecs. Hungary
| | - Mallikarjuna R Pabbidi
- Department of Pharmacology and Toxicology, University of Mississippi Medical Center, Jackson, Mississippi
| | - Krisztina Amrein
- Cerebrovascular Laboratory, Department of Neurosurgery, Medical School University of Pecs, Pecs. Hungary.,Neurotrauma Research Group, Janos Szentagothai Research Center, Medical School University of Pecs, Pecs. Hungary
| | - Endre Czeiter
- Cerebrovascular Laboratory, Department of Neurosurgery, Medical School University of Pecs, Pecs. Hungary.,Neurotrauma Research Group, Janos Szentagothai Research Center, Medical School University of Pecs, Pecs. Hungary.,MTA-PTE Clinical Neuroscience MR Research Group, Pecs, Hungary
| | - Gergely Berta
- Department of Medical Biology, Medical School University of Pecs, Pecs. Hungary
| | - Krisztina Pohoczky
- Department of Pharmacology and Pharmacotherapy, Medical School University of Pecs, Pecs. Hungary.,MTA-PTE NAP B Chronic Pain Research Group, Pecs, Hungary
| | - Zsuzsanna Helyes
- Department of Pharmacology and Pharmacotherapy, Medical School University of Pecs, Pecs. Hungary.,MTA-PTE NAP B Chronic Pain Research Group, Pecs, Hungary
| | - Zoltan Ungvari
- Reynolds Oklahoma Center on Aging, Donald W. Reynolds Department of Geriatric Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma
| | - Akos Koller
- Cerebrovascular Laboratory, Department of Neurosurgery, Medical School University of Pecs, Pecs. Hungary.,Institute of Natural Sciences, University of Physical Education, Budapest, Hungary.,Department of Physiology, New York Medical College, Valhalla, New York
| | - Andras Buki
- Cerebrovascular Laboratory, Department of Neurosurgery, Medical School University of Pecs, Pecs. Hungary.,Neurotrauma Research Group, Janos Szentagothai Research Center, Medical School University of Pecs, Pecs. Hungary
| | - Peter Toth
- Cerebrovascular Laboratory, Department of Neurosurgery, Medical School University of Pecs, Pecs. Hungary.,Neurotrauma Research Group, Janos Szentagothai Research Center, Medical School University of Pecs, Pecs. Hungary.,Department of Translational Medicine, Medical School University of Pecs, Pecs. Hungary.,MTA-PTE Clinical Neuroscience MR Research Group, Pecs, Hungary.,Reynolds Oklahoma Center on Aging, Donald W. Reynolds Department of Geriatric Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma
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Treu C, de Souza MDGC, Lupi O, Sicuro FL, Maranhão PA, Kraemer-Aguiar LG, Bouskela E. Structural and functional changes in the microcirculation of lepromatous leprosy patients - Observation using orthogonal polarization spectral imaging and laser Doppler flowmetry iontophoresis. PLoS One 2017; 12:e0175743. [PMID: 28419120 PMCID: PMC5395185 DOI: 10.1371/journal.pone.0175743] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2016] [Accepted: 03/30/2017] [Indexed: 01/22/2023] Open
Abstract
Leprosy is a chronic granulomatous infection of skin and peripheral nerves caused by Mycobacterium leprae and is considered the main infectious cause of disability worldwide. Despite the several studies regarding leprosy, little is known about its effects on microvascular structure and function in vivo. Thus, we have aimed to compare skin capillary structure and functional density, cutaneous vasomotion (spontaneous oscillations of arteriolar diameter), which ensures optimal blood flow distribution to skin capillaries) and cutaneous microvascular blood flow and reactivity between ten men with lepromatous leprosy (without any other comorbidity) and ten age- and gender-matched healthy controls. Orthogonal polarization spectral imaging was used to evaluate skin capillary morphology and functional density and laser Doppler flowmetry to evaluate blood flow, vasomotion and spectral analysis of flowmotion (oscillations of blood flow generated by vasomotion) and microvascular reactivity, in response to iontophoresis of acetylcholine and sodium nitroprusside. The contribution of different frequency components of flowmotion (endothelial, neurogenic, myogenic, respiratory and cardiac) was not statistically different between groups. However, endothelial-dependent and -independent vasodilatations elicited by acetylcholine and sodium nitroprusside iontophoresis, respectively, were significantly reduced in lepromatous leprosy patients compared to controls, characterizing the existence of microvascular dysfunction. These patients also presented a significant increase in the number of capillaries with morphological abnormalities and in the diameters of the dermal papilla and capillary bulk when compared to controls. Our results suggest that lepromatous leprosy causes severe microvascular dysfunction and significant alterations in capillary structure. These structural and functional changes are probably induced by exposure of the microvascular bed to chronic inflammation evoked by the Mycobacterium leprae.
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Affiliation(s)
- Curt Treu
- Laboratório de Pesquisas Clínicas e Experimentais em Biologia Vascular, Centro Biomédico, Universidade do Estado do Rio de Janeiro (UERJ), Rio de Janeiro, Rio de Janeiro, Brazil
| | - Maria das Graças Coelho de Souza
- Laboratório de Pesquisas Clínicas e Experimentais em Biologia Vascular, Centro Biomédico, Universidade do Estado do Rio de Janeiro (UERJ), Rio de Janeiro, Rio de Janeiro, Brazil
- * E-mail:
| | - Omar Lupi
- Departamento de Dermatologia, Universidade Federal do Estado do Rio de Janeiro (Uni-Rio), Rio de Janeiro, Rio de Janeiro, Brazil
| | - Fernando Lencastre Sicuro
- Laboratório de Pesquisas Clínicas e Experimentais em Biologia Vascular, Centro Biomédico, Universidade do Estado do Rio de Janeiro (UERJ), Rio de Janeiro, Rio de Janeiro, Brazil
| | - Priscila Alves Maranhão
- Laboratório de Pesquisas Clínicas e Experimentais em Biologia Vascular, Centro Biomédico, Universidade do Estado do Rio de Janeiro (UERJ), Rio de Janeiro, Rio de Janeiro, Brazil
| | - Luiz Guilherme Kraemer-Aguiar
- Laboratório de Pesquisas Clínicas e Experimentais em Biologia Vascular, Centro Biomédico, Universidade do Estado do Rio de Janeiro (UERJ), Rio de Janeiro, Rio de Janeiro, Brazil
- Ambulatório de Obesidade, Policlínica Piquet Carneiro, Departamento de Medicina Interna, Faculdade de Ciências Médicas, Centro Biomédico, Universidade do Estado do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Eliete Bouskela
- Laboratório de Pesquisas Clínicas e Experimentais em Biologia Vascular, Centro Biomédico, Universidade do Estado do Rio de Janeiro (UERJ), Rio de Janeiro, Rio de Janeiro, Brazil
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Toth P, Szarka N, Farkas E, Ezer E, Czeiter E, Amrein K, Ungvari Z, Hartings JA, Buki A, Koller A. Traumatic brain injury-induced autoregulatory dysfunction and spreading depression-related neurovascular uncoupling: Pathomechanisms, perspectives, and therapeutic implications. Am J Physiol Heart Circ Physiol 2016; 311:H1118-H1131. [PMID: 27614225 PMCID: PMC5504422 DOI: 10.1152/ajpheart.00267.2016] [Citation(s) in RCA: 62] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/31/2016] [Accepted: 08/19/2016] [Indexed: 01/17/2023]
Abstract
Traumatic brain injury (TBI) is a major health problem worldwide. In addition to its high mortality (35-40%), survivors are left with cognitive, behavioral, and communicative disabilities. While little can be done to reverse initial primary brain damage caused by trauma, the secondary injury of cerebral tissue due to cerebromicrovascular alterations and dysregulation of cerebral blood flow (CBF) is potentially preventable. This review focuses on functional, cellular, and molecular changes of autoregulatory function of CBF (with special focus on cerebrovascular myogenic response) that occur in cerebral circulation after TBI and explores the links between autoregulatory dysfunction, impaired myogenic response, microvascular impairment, and the development of secondary brain damage. We further provide a synthesized translational view of molecular and cellular mechanisms involved in cortical spreading depolarization-related neurovascular dysfunction, which could be targeted for the prevention or amelioration of TBI-induced secondary brain damage.
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Affiliation(s)
- Peter Toth
- Department of Neurosurgery, University of Pecs, Pecs, Hungary;
- Janos Szentagothai Research Centre, University of Pecs, Pecs, Hungary
- Department of Geriatric Medicine, Reynolds Oklahoma Center on Aging, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma
| | - Nikolett Szarka
- Department of Neurosurgery, University of Pecs, Pecs, Hungary
- Department of Translational Medicine, University of Pecs, Pecs, Hungary
| | - Eszter Farkas
- Faculty of Medicine and Faculty of Science and Informatics, Department of Medical Physics and Informatics, University of Szeged, Szeged, Hungary
| | - Erzsebet Ezer
- Department of Neurosurgery, University of Pecs, Pecs, Hungary
| | - Endre Czeiter
- Department of Neurosurgery, University of Pecs, Pecs, Hungary
- Janos Szentagothai Research Centre, University of Pecs, Pecs, Hungary
- MTA-PTE Clinical Neuroscience MR Research Group, Pecs, Hungary
| | - Krisztina Amrein
- Department of Neurosurgery, University of Pecs, Pecs, Hungary
- Janos Szentagothai Research Centre, University of Pecs, Pecs, Hungary
- MTA-PTE Clinical Neuroscience MR Research Group, Pecs, Hungary
| | - Zoltan Ungvari
- Department of Geriatric Medicine, Reynolds Oklahoma Center on Aging, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma
| | - Jed A Hartings
- Department of Neurosurgery, University of Cincinnati College of Medicine, Cincinnati, Ohio
| | - Andras Buki
- Department of Neurosurgery, University of Pecs, Pecs, Hungary
- Janos Szentagothai Research Centre, University of Pecs, Pecs, Hungary
- MTA-PTE Clinical Neuroscience MR Research Group, Pecs, Hungary
| | - Akos Koller
- Department of Neurosurgery, University of Pecs, Pecs, Hungary
- Janos Szentagothai Research Centre, University of Pecs, Pecs, Hungary
- Institute of Natural Sciences, University of Physical Education, Budapest, Hungary; and
- Department of Physiology, New York Medical College, Valhalla, New York
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Abstract
Intrarenal autoregulatory mechanisms maintain renal blood flow (RBF) and glomerular filtration rate (GFR) independent of renal perfusion pressure (RPP) over a defined range (80-180 mmHg). Such autoregulation is mediated largely by the myogenic and the macula densa-tubuloglomerular feedback (MD-TGF) responses that regulate preglomerular vasomotor tone primarily of the afferent arteriole. Differences in response times allow separation of these mechanisms in the time and frequency domains. Mechanotransduction initiating the myogenic response requires a sensing mechanism activated by stretch of vascular smooth muscle cells (VSMCs) and coupled to intracellular signaling pathways eliciting plasma membrane depolarization and a rise in cytosolic free calcium concentration ([Ca(2+)]i). Proposed mechanosensors include epithelial sodium channels (ENaC), integrins, and/or transient receptor potential (TRP) channels. Increased [Ca(2+)]i occurs predominantly by Ca(2+) influx through L-type voltage-operated Ca(2+) channels (VOCC). Increased [Ca(2+)]i activates inositol trisphosphate receptors (IP3R) and ryanodine receptors (RyR) to mobilize Ca(2+) from sarcoplasmic reticular stores. Myogenic vasoconstriction is sustained by increased Ca(2+) sensitivity, mediated by protein kinase C and Rho/Rho-kinase that favors a positive balance between myosin light-chain kinase and phosphatase. Increased RPP activates MD-TGF by transducing a signal of epithelial MD salt reabsorption to adjust afferent arteriolar vasoconstriction. A combination of vascular and tubular mechanisms, novel to the kidney, provides for high autoregulatory efficiency that maintains RBF and GFR, stabilizes sodium excretion, and buffers transmission of RPP to sensitive glomerular capillaries, thereby protecting against hypertensive barotrauma. A unique aspect of the myogenic response in the renal vasculature is modulation of its strength and speed by the MD-TGF and by a connecting tubule glomerular feedback (CT-GF) mechanism. Reactive oxygen species and nitric oxide are modulators of myogenic and MD-TGF mechanisms. Attenuated renal autoregulation contributes to renal damage in many, but not all, models of renal, diabetic, and hypertensive diseases. This review provides a summary of our current knowledge regarding underlying mechanisms enabling renal autoregulation in health and disease and methods used for its study.
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Affiliation(s)
- Mattias Carlström
- Department of Medicine, Division of Nephrology and Hypertension and Hypertension, Kidney and Vascular Research Center, Georgetown University, Washington, District of Columbia; Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden; and Department of Cell Biology and Physiology, UNC Kidney Center, and McAllister Heart Institute, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Christopher S Wilcox
- Department of Medicine, Division of Nephrology and Hypertension and Hypertension, Kidney and Vascular Research Center, Georgetown University, Washington, District of Columbia; Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden; and Department of Cell Biology and Physiology, UNC Kidney Center, and McAllister Heart Institute, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - William J Arendshorst
- Department of Medicine, Division of Nephrology and Hypertension and Hypertension, Kidney and Vascular Research Center, Georgetown University, Washington, District of Columbia; Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden; and Department of Cell Biology and Physiology, UNC Kidney Center, and McAllister Heart Institute, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
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Toth P, Csiszar A, Tucsek Z, Sosnowska D, Gautam T, Koller A, Schwartzman ML, Sonntag WE, Ungvari Z. Role of 20-HETE, TRPC channels, and BKCa in dysregulation of pressure-induced Ca2+ signaling and myogenic constriction of cerebral arteries in aged hypertensive mice. Am J Physiol Heart Circ Physiol 2013; 305:H1698-708. [PMID: 24097425 DOI: 10.1152/ajpheart.00377.2013] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Hypertension in the elderly substantially increases the risk of stroke and vascular cognitive impairment in part due to an impaired functional adaptation of aged cerebral arteries to high blood pressure. To elucidate the mechanisms underlying impaired autoregulatory protection in aging, hypertension was induced in young (3 mo) and aged (24 mo) C57BL/6 mice by chronic infusion of angiotensin II and pressure-induced changes in smooth muscle cell (SMC) intracellular Ca(2+) concentration ([Ca(2+)]i) and myogenic constriction of middle cerebral arteries (MCA) were assessed. In MCAs from young hypertensive mice, pressure-induced increases in vascular SMC [Ca(2+)]i and myogenic tone were increased, and these adaptive responses were inhibited by the cytochrome P-450 ω-hydroxylase inhibitor HET0016 and the transient receptor potential (TRP) channel blocker SKF96365. Administration of 20- hydroxyeicosatetraenoic acid (HETE) increased SMC [Ca(2+)]i and constricted MCAs, and these responses were inhibited by SKF96365. MCAs from aged hypertensive mice did not show adaptive increases in pressure-induced calcium signal and myogenic tone and responses to HET0016 and SKF96365 were blunted. Inhibition of large-conductance Ca(2+)-activated K(+) (BK) channels by iberiotoxin enhanced SMC [Ca(2+)]i and myogenic constriction in MCAs of young normotensive animals, whereas it was without effect in MCAs of young hypertensive mice. Iberiotoxin did not restore myogenic adaptation in MCAs of aged hypertensive mice. Thus functional maladaptation of aged cerebral arteries to hypertension is due to the dysregulation of pressure-induced 20-HETE and TRP channel-mediated SMC calcium signaling, whereas overactivation of BK channels is unlikely to play a role in this phenomenon.
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Affiliation(s)
- Peter Toth
- Reynolds Oklahoma Center on Aging, Department of Geriatric Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma
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Nakabayashi S, Nagaoka T, Tani T, Sogawa K, Hein TW, Kuo L, Yoshida A. Retinal arteriolar responses to acute severe elevation in systemic blood pressure in cats: role of endothelium-derived factors. Exp Eye Res 2012; 103:63-70. [PMID: 22940370 DOI: 10.1016/j.exer.2012.08.007] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2012] [Revised: 08/15/2012] [Accepted: 08/17/2012] [Indexed: 11/24/2022]
Abstract
The purpose of this study was to investigate the roles of endothelium-derived factors in the retinal arteriolar responses to acute severe elevation in systemic blood pressure (BP) in cats. Acute elevation of mean arterial BP by 60% for 5 min was achieved by inflating a balloon-tipped catheter in the descending aorta. The retinal arteriolar diameter, flow velocity, wall shear rate (WSR) and blood flow (RBF) changes during BP elevation were assessed with laser Doppler velocimetry 2 h after intravitreal injections of nitric oxide (NO) synthase inhibitor l-NAME, cyclooxygenase inhibitor indomethacin, endothelin-1 receptor antagonists (BQ-123 for type A and BQ-788 for type B), or Rho kinase inhibitor fasudil. BP elevation caused a marked increase in retinal arteriolar flow velocity and WSR with slight vasoconstriction, resulting in an increase in RBF. The increases in velocity, WSR and RBF, but not diameter, were correlated with the increase in ocular perfusion pressure. With l-NAME or indomethacin, the increase in RBF upon BP elevation was significantly attenuated due to enhanced retinal arteriolar vasoconstriction. In contrast, BQ-123 and fasudil potentiated the increased RBF. BQ-788 had no effect on arteriolar diameter and hemodynamics. Our data suggest that acute elevation of BP by 60% leads to an increase in RBF due to the release of NO and prostanoids probably through a shear stress-induced vasodilation mechanism. The release of endothelin-1 and Rho kinase activation help to limit RBF augmentation by counteracting the vasodilation. It appears that the retinal endothelium, by releasing vasoactive substances, contributes to RBF regulation during acute severe elevation of systemic blood pressure.
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Affiliation(s)
- Seigo Nakabayashi
- Department of Ophthalmology, Asahikawa Medical University, Midorigaoka Higashi 2-1-1-1, Asahikawa 078-8510, Japan
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Koller A, Toth P. Contribution of flow-dependent vasomotor mechanisms to the autoregulation of cerebral blood flow. J Vasc Res 2012; 49:375-89. [PMID: 22739136 PMCID: PMC3586555 DOI: 10.1159/000338747] [Citation(s) in RCA: 85] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2011] [Accepted: 04/04/2012] [Indexed: 11/19/2022] Open
Abstract
Regulation of cerebral blood flow (CBF) is the result of multilevel mechanisms to maintain the appropriate blood supply to the brain while having to comply with the limited space available in the cranium. The latter requirement is ensured by the autoregulation of CBF, in which the pressure-sensitive myogenic response is known to play a pivotal role. However, in vivo increases in pressure are accompanied by increases in flow; yet the effects of flow on the vasomotor tone of cerebral vessels are less known. Earlier studies showed flow-sensitive dilation and/or constriction or both, but no clear picture emerged. Recently, the important role of flow-sensitive mechanism(s) eliciting the constriction of cerebral vessels has been demonstrated. This review focuses on the effect of hemodynamic forces (especially intraluminal flow) on the vasomotor tone of cerebral vessels and the underlying cellular and molecular mechanisms. A novel concept of autoregulation of CBF is proposed, suggesting that (in certain areas of the cerebrovascular tree) pressure- and flow-induced constrictions together maintain an effective autoregulation, and that alterations in these mechanisms may contribute to the development of cerebrovascular disorders. Future studies are warranted to explore the signals, the details of signaling processes and the in vivo importance of these mechanisms.
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Affiliation(s)
- Akos Koller
- Department of Pathophysiology and Gerontology, Medical School, University of Pécs, Pécs, Hungary.
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Satoh M, Haruna Y, Fujimoto S, Sasaki T, Kashihara N. Telmisartan improves endothelial dysfunction and renal autoregulation in Dahl salt-sensitive rats. Hypertens Res 2010; 33:135-42. [PMID: 19927153 DOI: 10.1038/hr.2009.190] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Hypertensive vascular disorders are characterized by endothelial dysfunction. Loss of renal autoregulation causes glomerular hypertension. However, the relationship between the autoregulatory response and glomerular damage has not been well examined. We examined the contributions of uncoupled endothelial nitric oxide synthase (eNOS) in hypertensive renal disease, and the relationship between the degree of autoregulation impairment and glomerular injury. We also investigated the effects of telmisartan on eNOS coupling and renal autoregulation. Male Dahl salt-sensitive hypertensive (DS) rats (14-week old) fed an 8% salt diet were used to examine endothelial dysfunction and impaired renal autoregulation caused by glomerular hypertension. Some DS rats were treated with telmisartan (3.0 mg kg(-1) day(-1)), an angiotensin receptor blocker, for 2 weeks. Increased superoxide production and decreased nitric oxide production, as detected by fluorescent indicator perfusion methods, were observed in the glomeruli and arterioles of hypertensive DS rats. Telmisartan improved the imbalance of superoxide and nitric oxide in the glomeruli and arterioles. Decreased serum tetrahydrobiopterin levels and coupled eNOS seen in the DS rat kidney were improved with telmisartan treatment. The endothelial relaxation reaction was impaired in DS rat aortic arteries. Autoregulatory capacity in response to step changes in perfusion pressure was also impaired in DS rat kidney. Treatment with telmisartan improved these abnormalities. Endothelial dysfunction in the glomeruli and impaired renal autoregulation, which may cause glomerular sclerosis, were observed in DS rat kidney. Telmisartan treatment improves these dysfunctions in hypertensive renal disease.
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Affiliation(s)
- Minoru Satoh
- Division of Nephrology, Department of Internal Medicine, Kawasaki Medical School, Kurashiki, Okayama, Japan.
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11
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Dreiza CM, Komalavilas P, Furnish EJ, Flynn CR, Sheller MR, Smoke CC, Lopes LB, Brophy CM. The small heat shock protein, HSPB6, in muscle function and disease. Cell Stress Chaperones 2010; 15:1-11. [PMID: 19568960 PMCID: PMC2866971 DOI: 10.1007/s12192-009-0127-8] [Citation(s) in RCA: 72] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2009] [Accepted: 06/05/2009] [Indexed: 10/20/2022] Open
Abstract
The small heat shock protein, HSPB6, is a 17-kDa protein that belongs to the small heat shock protein family. HSPB6 was identified in the mid-1990s when it was recognized as a by-product of the purification of HSPB1 and HSPB5. HSPB6 is highly and constitutively expressed in smooth, cardiac, and skeletal muscle and plays a role in muscle function. This review will focus on the physiologic and biochemical properties of HSPB6 in smooth, cardiac, and skeletal muscle; the putative mechanisms of action; and therapeutic implications.
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Ungvari Z, Wolin MS, Csiszar A. Mechanosensitive production of reactive oxygen species in endothelial and smooth muscle cells: role in microvascular remodeling? Antioxid Redox Signal 2006; 8:1121-9. [PMID: 16910760 DOI: 10.1089/ars.2006.8.1121] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Changes in the hemodynamic environment (e.g., hypertension, increased blood flow/shear stress) are known to lead to vascular remodeling; however, the underlying mechanisms by which hemodynamic forces control gene expression in vascular cells are not yet completely understood. This review considers how mechanosensitive generation of reactive oxygen species (ROS) by NAD(P)H oxidases and other sources interacts with downstream signaling systems [including activation of nuclear factor kappa B (NF-kappaB) and AP-1] that modulate the phenotype of endothelial and smooth muscle cells, leading to vascular remodeling. We propose a model for an interaction between direct mechanosensitive ROS signaling and pathways activated by pressure-induced upregulation of prooxidant paracrine signaling mechanisms [local renin-angiotensin system, TNF-alpha- converting enzyme (TACE)/tumor necrosis factor alpha (TNF-alpha) system, and endothelin signaling].
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Affiliation(s)
- Zoltan Ungvari
- Department of Physiology, New York Medical College, Valhalla, 10595, USA.
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14
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Abstract
BACKGROUND One variant of postural tachycardia syndrome (POTS), designated low-flow POTS, is associated with decreased peripheral blood flow related to impaired local vascular regulation. METHODS AND RESULTS To investigate the hypothesis that microvascular endothelial dysfunction produces decreased peripheral blood flow in low-flow POTS, we performed experiments using laser-Doppler flowmetry (LDF) combined with iontophoresis in 15 low-flow POTS patients, 17 normal-flow POTS patients, and 13 healthy reference volunteers varying in age from 14 to 22 years. We tested whether alpha-adrenergic vasoregulation was impaired using iontophoretic delivery of tyramine, phentolamine, and bretylium followed by a norepinephrine dose response. We tested endothelial-dependent and -independent receptor-mediated vasodilation by measuring acetylcholine and sodium nitroprusside dose responses. We tested whether nitric oxide-dependent vasodilation was different in these groups by testing the local thermal hyperemic response to saline used as a reference compared with the nitric oxide synthase inhibitor NG-nitro-L-arginine methyl ester (L-NAME). Adrenergic and receptor-dependent cutaneous vasoregulation was similar for low-flow POTS, normal-flow POTS, and reference subjects. Thermal hyperemia produced distinctly different findings: there was marked attenuation of the nitric oxide-sensitive plateau during prolonged heating, which was insensitive to L-NAME in low-flow POTS subjects. The pattern of thermal hyperemia response in low-flow POTS subjects during saline administration resembled the pattern in reference subjects during L-NAME administration and was minimally affected by L-NAME. CONCLUSIONS The data suggest that flow-dependent nitric oxide release is reduced in low-flow POTS. This may account for local flow regulation abnormalities.
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15
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Teixeira CE, Priviero FBM, Webb RC. Differential effects of the phosphodiesterase type 5 inhibitors sildenafil, vardenafil, and tadalafil in rat aorta. J Pharmacol Exp Ther 2005; 316:654-61. [PMID: 16204472 DOI: 10.1124/jpet.105.092544] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Presumably, the vasorelaxant properties of phosphodiesterase type 5 (PDE5) inhibitors are similar in isolated blood vessels. We aimed to explore the mechanisms underlying the vasorelaxation induced by the selective PDE5 inhibitors sildenafil, vardenafil, and tadalafil in the rat aorta. Aortic rings were mounted in 5-ml organ baths, and concentration-response curves for PDE5 inhibitors (0.0001-10 microM) were constructed in phenylephrine (PE)-precontracted endothelium-intact and -denuded rings. Cyclic nucleotides were measured using enzyme immunoassay kits. Sildenafil, vardenafil, and tadalafil concentration dependently relaxed aortic rings and increased cGMP, but not cAMP, concentrations. Endothelium denudation caused marked rightward shifts in the curves to sildenafil (45-fold), tadalafil (21-fold), and vardenafil (251-fold). Maximal responses to sildenafil and tadalafil were substantially reduced (38 +/- 1% and 53 +/- 2%, respectively), whereas that evoked by vardenafil was not affected. Likewise, inhibition of NO synthase (N(omega)-nitro-L-arginine methyl ester, 100 microM), guanylyl cyclase (1H-[1,2,4]oxadiazolo [4,3,-a]quinoxalin-1-one, 10 microM), or scavenging of NO ([carboxy-PTIO (2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide), 100 microM]) caused similar attenuation of the vasorelaxations evoked by PDE5 inhibitors. Sildenafil, tadalafil, and vardenafil significantly potentiated relaxations mediated by glyceryl trinitrate (0.0001-3 microM; 8-13-fold) and atrial natriuretic peptide (0.1-100 nM; 2-3-fold). Contractions evoked by CaCl(2) (0.01-5 mM) in PE-treated rings were significantly reduced (26 +/- 4%) by vardenafil, but not sildenafil or tadalafil, whereas phorbol 12,13-dibutyrate-induced contractions were not affected. Ouabain, cyclopiazonic acid, and calyculin A failed to affect vasorelaxations induced by the PDE5 inhibitors. These results suggest that vardenafil, but not sildenafil or tadalafil, affects Ca(2+) handling in the rat aorta in addition to increasing cGMP levels through inhibition of PDE5 to cause relaxation.
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Affiliation(s)
- Cleber E Teixeira
- Department of Physiology, Medical College of Georgia, Augusta, 30912-3000, USA.
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16
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Kim MH, Harris NR, Korzick DH, Tarbell JM. Control of the arteriolar myogenic response by transvascular fluid filtration. Microvasc Res 2004; 68:30-7. [PMID: 15219418 DOI: 10.1016/j.mvr.2004.03.002] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2003] [Indexed: 11/16/2022]
Abstract
Mechanisms of the myogenic response have not been completely established. We hypothesized that transvascular fluid filtration from plasma across smooth muscle cells (SMC) and into the surrounding interstitium helps regulate arteriolar myogenic tone. Arteriolar diameters in the rat mesentery were monitored before and following vascular occlusion with a glass micropipette. Arteriolar occlusion not only gave an increase in hydrostatic pressure that initiated myogenic constriction upstream of the pipette, but also allowed measurement of fluid filtration rate by monitoring the movement of vascular red blood cells. A statistically significant correlation (P < 0.001) existed between basal myogenic tone and fluid filtration. Additionally, the myogenic response was attenuated by 47% +/- 7% (N = 10) when an osmotic solution of albumin or albumin plus Ficoll was infused into the bloodstream to decrease fluid filtration by 53% +/- 3%. Moreover, the same inhibition of myogenic tone was found in isolated, cannulated rat soleus muscle arterioles when filtration was osmotically attenuated by intravascular dextran. Taken together, these results are consistent with the hypothesis that shear stress on arteriolar smooth muscle, induced by transvascular fluid filtration, is a contributing factor that helps control myogenic tone.
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Affiliation(s)
- Min-ho Kim
- Department of Bioengineering, Pennsylvania State University, University Park, PA 16802, USA
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Szekeres M, Nádasy GL, Kaley G, Koller A. Nitric Oxide and Prostaglandins Modulate Pressure-Induced Myogenic Responses of Intramural Coronary Arterioles. J Cardiovasc Pharmacol 2004; 43:242-9. [PMID: 14716212 DOI: 10.1097/00005344-200402000-00012] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
The myogenic response, an active constriction and dilation of vessels to changes in intravascular pressure, can play an important role in the regulation of coronary blood flow. The characteristics of the myogenic response and its modulation by endothelium-derived factors are organ and location specific and have not been studied extensively in intramural coronary arterioles. Thus, distal intramural branches (approximately 100 and approximately 170 microm active and passive diameter, respectively) of the left anterior descending coronary artery of rats were isolated and cannulated. Step increases in intraluminal pressure from 0 to 40 mm Hg elicited increases in diameter, whereas further increases in pressure from 50 to 150 mm Hg resulted in constrictions. In control, the pressure-induced myogenic tone of coronary arterioles was 67.3 +/- 2.7% of passive diameter (PD, obtained in Ca2+-free solution) at 60 mm Hg. Nomega-nitro-L-arginine (L-NNA, 10(-5) M), an inhibitor of nitric oxide synthase, reduced the initial arteriolar diameter (by 44.8 +/- 5.1 microm at 2 mm Hg, P < 0.05) and significantly mitigated increases in diameter to lower pressures and constrictions to higher pressures (41.1 +/- 5.6% of PD at 60 mm Hg). Administration of adenosine restored the initial diameter in the presence of l-NNA, but the increase in diameter to lower pressures and the decrease in diameter to higher pressures observed under control conditions remained greatly inhibited. Inhibition of prostaglandin synthesis, or PGH2/TxA2 receptors significantly reduced the constrictions to higher pressures as compared with control (indomethacin: from 57.9 +/- 4.8% of PD to 67.0 +/- 4.7% of PD at 150 mm Hg). Thus, because in isolated intramural coronary arterioles of rats a negative slope for the pressure-diameter curve develops only in the presence of nitric oxide and constrictor prostaglandins, they seem to be essential for the normal development of the myogenic response.
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Affiliation(s)
- Maria Szekeres
- Department of Physiology, New York Medical College, Valhalla, New York 10595, USA.
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Stewart JM, Medow MS, Montgomery LD. Local vascular responses affecting blood flow in postural tachycardia syndrome. Am J Physiol Heart Circ Physiol 2003; 285:H2749-56. [PMID: 12919934 DOI: 10.1152/ajpheart.00429.2003] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Postural tachycardia syndrome (POTS) is defined by orthostatic intolerance associated with abnormal upright tachycardia. Some patients have defective peripheral vasoconstriction and increased calf blood flow. Others have increased peripheral arterial resistance and decreased blood flow. In 14 POTS patients (13-19 yr) evenly subdivided among low-flow POTS (LFP) and high-flow POTS (HFP) we tested the hypothesis that myogenic, venoarteriolar, and reactive hyperemic responses are abnormal. We used venous occlusion plethysmography to measure calf venous pressure and blood flow in the supine position and when the calf was lowered by 40 cm to evoke myogenic and venoarteriolar responses and during venous hypertension by 40-mmHg occlusion to evoke the venoarteriolar response. We measured calf reactive hyperemia with plethysmography and cutaneous laser-Doppler flowmetry. Baseline blood flow in LFP was reduced compared with HFP and control subjects (0.8 +/- 0.2 vs. 4.4 +/- 0.5 and 2.7 +/- 0.4 ml.min-1.100 ml-1) but increased during leg lowering (1.2 +/- 0.5 ml.min-1. 100 ml-1) while decreasing in the others. Baseline peripheral arterial resistance was increased in LFP and decreased in HFP compared with control subjects (39 +/- 13 vs. 15 +/- 3 and 22 +/- 5 mmHg.ml-1. 100 ml. min) but decreased to 29 +/- 13 mmHg.ml-1.100 ml. min in LFP during venous hypertension. Resistance increased in the other groups. Maximum calf hyperemic flow and cutaneous flow were similar in all subjects. The duration of hyperemic blood flow was curtailed in LFP compared with either control or HFP subjects (plethysmographic time constant = 20 +/- 2 vs. 29 +/- 4 and 28 +/- 4 s; cutaneous time constant = 60 +/- 25 vs. 149 +/- 53 s in controls). Local blood flow regulation in low-flow POTS is impaired.
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Affiliation(s)
- Julian M Stewart
- Department of Pediatrics, Center for Pediatric Hypotension and Division of Pediatric Cardiology, Suite 618, Munger Pavilion, New York Medical College, Valhalla, NY 10595, USA.
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Frisbee JC, Maier KG, Falck JR, Roman RJ, Lombard JH. Integration of hypoxic dilation signaling pathways for skeletal muscle resistance arteries. Am J Physiol Regul Integr Comp Physiol 2002; 283:R309-19. [PMID: 12121842 DOI: 10.1152/ajpregu.00741.2001] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Mediator contributions to hypoxic dilation of rat gracilis muscle resistance arteries were determined by measuring dilation, vascular smooth muscle hyperpolarization, and metabolite production after incremental hypoxia. Nitric oxide (NO) synthase inhibition abolished responses to mild hypoxia, whereas COX inhibition impaired responses to more severe hypoxia by 77%. Blocking 20-hydroxyeicosatetraenoic acid (20-HETE) impaired responses to moderate hypoxia. With only NO systems intact, responses were maintained with mild hypoxia (88% normal) mediated via K(Ca) channels. When only COX pathways were intact, responses to moderate-severe hypoxia were largely retained (79% of normal) mediated via K(ATP) channels. Vessel responses to moderate hypoxia were retained with only 20-HETE systems intact mediated via K(Ca) channels. NO production increased 5.6-fold with mild hypoxia; greater hypoxia was without further effect. With increased hypoxia, 20-HETE levels fell to 40% of control values. 6-keto-PGF(1alpha) levels were not altered with mild hypoxia, but increased 4.6-fold with severe hypoxia. These results suggest vascular reactivity to progressive hypoxia represents an integration of NO production (mild hypoxia), PGI(2) production (severe hypoxia), and reduced 20-HETE levels (moderate hypoxia).
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Affiliation(s)
- Jefferson C Frisbee
- Department of Physiology, Medical College of Wisconsin, Milwaukee, Wisconsin 53226, USA.
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