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Chilakala SK, Parfenova H, Pourcyrous M. The effects of sodium bicarbonate infusion on cerebrovascular function in newborn pigs. Pediatr Res 2022; 92:729-736. [PMID: 34862458 PMCID: PMC9163205 DOI: 10.1038/s41390-021-01876-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/11/2021] [Revised: 11/11/2021] [Accepted: 11/13/2021] [Indexed: 11/09/2022]
Abstract
BACKGROUND Sodium bicarbonate (NaHCO3) is no longer recommended by the Neonatal Resuscitation Program (NRP), but is still being used by some neonatologists. The effects of NaHCO3 on cerebral hemodynamics are unclear. Therefore, we investigated the effects of NaHCO3 on cerebral blood flow (CBF) and cerebrovascular function using a newborn piglet model. METHODS Newborn pigs were anesthetized, intubated, and ventilated. Cranial windows were implanted to evaluate changes in pial arteriolar diameters (PADs) as a surrogate for CBF during a 4-h intravenous infusion of 3% NaHCO3. Cerebrovascular reactivity to vasodilators and vasoconstrictors was investigated during vehicle control and during NaHCO3 infusion. RESULTS NaHCO3 infusion caused significant and progressive pial arteriolar vasoconstrictions. During NaHCO3 infusion, cerebrovascular reactivity was preserved. Adding vasodilators decreased cerebral vasoconstriction, while adding vasoconstrictors exaggerated cerebral vasoconstriction. CONCLUSIONS Intravenous infusion of NaHCO3 over 4 h caused progressive vasoconstriction of pial arterioles. Cerebrovascular function evaluated by the responses of pial arterioles to physiologically relevant vasoconstrictors and vasodilators was preserved during NaHCO3 infusion. A notable additional reduction of PADs was observed during NaHCO3 infusion in the presence of vasoconstrictors. Extrapolating our findings to human neonates should alarm the clinicians that using NaHCO3 in neonates may cause cerebral hypoperfusion. IMPACT Cerebral vasoconstriction occurs during slow infusion of 3% diluted NaHCO3. Cerebral vasoconstriction is exaggerated when another vasoconstrictor is added during NaHCO3 infusion. Cerebrovascular function is preserved during NaHCO3 infusion. Clinicians should be aware of the risk of cerebral hypoperfusion with NaHCO3 infusion in vulnerable neonates.
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Affiliation(s)
- Sandeep K Chilakala
- Department of Pediatrics, University of Tennessee Health Science Center (UTHSC), Memphis, Tennessee
| | - Helena Parfenova
- Department of Physiology, University of Tennessee Health Science Center (UTHSC), Memphis, Tennessee
| | - Massroor Pourcyrous
- Department of Pediatrics, University of Tennessee Health Science Center (UTHSC), Memphis, TN, USA. .,Department of Physiology, University of Tennessee Health Science Center (UTHSC), Memphis, TN, USA. .,Department of Obstetrics/Gynecology, University of Tennessee Health Science Center (UTHSC), Memphis, TN, USA.
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Zhang R, Liu J, Parfenova H. The Cold Receptor TRPM8 Mediates the Antioxidant and Cytoprotective Effects of Mild Hypothermia in Cerebral Endothelial Cells During Inflammation. FASEB J 2022. [PMID: 35554295 DOI: 10.1096/fasebj.2022.36.s1.r5241] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Cerebral vascular endothelium, the key component of the neurovascular unit, is most vulnerable to oxidative stress injury. Our previous reports in newborn pigs indicated that brain hypothermia prevents cerebral endothelial injury by oxidative stress caused by neonatal seizures and asphyxia. We used primary cerebral vascular endothelial cells (CVEC) from newborn pigs as an in vitro model of oxidative stress condition in the brain caused by inflammation. During normothermia (37˚C), CVEC respond to a pro-inflammatory cytokine TNF-alpha (30 ng/ml) by excessive formation of reactive oxygen species (ROS) leading to cell death by apoptosis (caspase-3 activation, DNA fragmentation, loss of cell-cell contacts). Remarkably, mild hypothermia (24.5°C) reduced ROS and prevented apoptosis in CVEC exposed to TNF-alpha. We tested the hypothesis that the cold sensing menthol receptor TRPM8 mediates the cytoprotective effects of mild hypothermia in cerebral endothelium. TRPM8 (mRNA and protein) is expressed in CVEC. The TRPM8 agonist icilin (5 µM) reduced ROS and prevented apoptosis in CVEC exposed to TNF-alpha at 37˚C, thus mimicking the cytoprotective effects of mild cooling. The TRPM8 antagonist AMTB (20 µM) reversed the icilin-mediated cytoprotective effects during inflammation. The cell surface biotinylation technique suggested that mild hypothermia and icilin (at 37˚C) promote a time-dependent TRPM8 translocation from an intracellular compartment to the plasma membrane concomitantly with the receptor activation. We used the in vitro model of the blood-brain barrier (BBB) to test the functional consequences of TRPM8-mediated cytoprotection. Confluent monolayers of CVEC cultured on transwell inserts with semipermeable membranes were exposed to TNF-alpha during normothermia and mild hypothermia conditions. The BBB properties were detected by transendothelial electrical resistance (TEER) and the permeability to 3 kDa fluorescent Dextran. During a 2-6 h exposure to TNF-alpha at 37°C, TEER was time-dependently reduced, and the Dextran permeability was elevated indicating the BBB opening. Mild hypothermia (24.5°C) and icilin (at 37˚C) largely preserved the BBB properties during inflammatory conditions. Overall, our findings demonstrate that mild hypothermia, via a TRPM8-mediated mechanism, reduces oxidative stress, promotes cell survival, and prevents BBB damage during inflammation. The TRPM8 targeting approaches may provide a promising therapeutic strategy for cerebrovascular disease caused by brain inflammation.
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Affiliation(s)
- Rong Zhang
- Physiology, University of Tennessee Health Science Center, Memphis, TN
| | - Jianxiong Liu
- Physiology, University of Tennessee Health Science Center, Memphis, TN
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Liu J, Zhang R, Fedinec AL, Parfenova H. Acute Antioxidant and Cytoprotective Effects of Caffeine in the Model of Neurovascular Injury by Oxidative Stress. FASEB J 2022. [DOI: 10.1096/fasebj.2022.36.s1.r5144] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Jianxiong Liu
- PhysiologyUniversity of Tennessee Health Science CenterMemphisTN
| | - Rong Zhang
- PhysiologyUniversity of Tennessee Health Science CenterMemphisTN
| | - Alex L. Fedinec
- PhysiologyUniversity of Tennessee Health Science CenterMemphisTN
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Fedinec AL, Liu J, Zhang R, Harsono M, Pourcyrous M, Parfenova H. The cold receptor TRPM8 activation leads to attenuation of endothelium-dependent cerebral vascular functions during head cooling. J Cereb Blood Flow Metab 2021; 41:2897-2906. [PMID: 34013806 PMCID: PMC8756482 DOI: 10.1177/0271678x211018035] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Using the cranial window technique, we investigated acute effects of head cooling on cerebral vascular functions in newborn pigs. Head cooling lowered the rectal and extradural brain temperatures to 34.3 ± 0.6°C and 26.1 ± 0.6°C, respectively. During the 3-h hypothermia period, responses of pial arterioles to endothelium-dependent dilators bradykinin and glutamate were reduced, whereas the responses to hypercapnia and an endothelium-independent dilator sodium nitroprusside (SNP) remained intact. All vasodilator responses were restored after rewarming, suggesting that head cooling did not produce endothelial injury. We tested the hypothesis that the cold-sensitive TRPM8 channel is involved in attenuation of cerebrovascular functions. TRPM8 is immunodetected in cerebral vessels and in the brain parenchyma. During normothermia, the TRPM8 agonist icilin produced constriction of pial arterioles that was antagonized by the channel blocker AMTB. Icilin reduced dilation of pial arterioles to bradykinin and glutamate but not to hypercapnia and SNP, thus mimicking the effects of head cooling on vascular functions. AMTB counteracted the impairment of endothelium-dependent vasodilation caused by hypothermia or icilin. Overall, mild hypothermia produced by head cooling leads to acute reversible reduction of selected endothelium-dependent cerebral vasodilator functions via TRPM8 activation, whereas cerebral arteriolar smooth muscle functions are largely preserved.
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Affiliation(s)
| | | | | | | | | | - Helena Parfenova
- Helena Parfenova, Department of Physiology, University of Tennessee Health Science Center, 956 Court Avenue, Suite E332, Memphis, TN 38163, USA.
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Parfenova H, Liu J, Hoover DT, Fedinec AL. Vasodilator effects of sulforaphane in cerebral circulation: A critical role of endogenously produced hydrogen sulfide and arteriolar smooth muscle K ATP and BK channels in the brain. J Cereb Blood Flow Metab 2020; 40:1987-1996. [PMID: 31594422 PMCID: PMC7786849 DOI: 10.1177/0271678x19878284] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
We investigated the effects of sulforaphane (SFN), an isothiocyanate from cruciferous vegetables, in the regulation of cerebral blood flow using cranial windows in newborn pigs. SFN administered topically (10 µM-1 mM) or systemically (0.4 mg/kg ip) caused immediate and sustained dilation of pial arterioles concomitantly with elevated H2S in periarachnoid cortical cerebrospinal fluid. H2S is a potent vasodilator of cerebral arterioles. SFN is not a H2S donor but it acts via stimulating H2S generation in the brain catalyzed by cystathionine γ-lyase (CSE) and cystathionine β-synthase (CBS). CSE/CBS inhibitors propargylglycine, β-cyano-L-alanine, and aminooxyacetic acid blocked brain H2S generation and cerebral vasodilation caused by SFN. The SFN-elicited vasodilation requires activation of potassium channels in cerebral arterioles. The inhibitors of KATP and BK channels glibenclamide, paxilline, and iberiotoxin blocked the vasodilator effects of topical and systemic SFN, supporting the concept that H2S is the mediator of the vasodilator properties of SFN in cerebral circulation. Overall, we provide first evidence that SFN is a brain permeable compound that increases cerebral blood flow via a non-genomic mechanism that is mediated via activation of CSE/CBS-catalyzed H2S formation in neurovascular cells followed by H2S-induced activation of KATP and BK channels in arteriolar smooth muscle.
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Affiliation(s)
- Helena Parfenova
- Department of Physiology, University of Tennessee Health Science Center, Memphis, TN, USA
| | - Jianxiong Liu
- Department of Physiology, University of Tennessee Health Science Center, Memphis, TN, USA
| | - Daniel T Hoover
- Department of Physiology, University of Tennessee Health Science Center, Memphis, TN, USA
| | - Alex L Fedinec
- Department of Physiology, University of Tennessee Health Science Center, Memphis, TN, USA
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Liu J, Chandaka GK, Zhang R, Parfenova H. Acute antioxidant and cytoprotective effects of sulforaphane in brain endothelial cells and astrocytes during inflammation and excitotoxicity. Pharmacol Res Perspect 2020; 8:e00630. [PMID: 32715644 PMCID: PMC7383090 DOI: 10.1002/prp2.630] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2020] [Revised: 06/29/2020] [Accepted: 06/30/2020] [Indexed: 01/01/2023] Open
Abstract
Sulforaphane (SFN), a bioactive phytochemical isothiocyanate, has a wide spectrum of cytoprotective effects that involve induction of antioxidant genes. Nongenomic antioxidant effects of SFN have not been investigated. Brain oxidative stress during inflammation and excitotoxicity leads to neurovascular injury. We tested the hypothesis that SNF exhibits acute antioxidant effects and prevents neurovascular injury during oxidative stress. In primary cultures of cerebral microvascular endothelial cells (CMVEC) and cortical astrocytes from the newborn pig brain, a pro-inflammatory cytokine TNF-α and an excitotoxic glutamate elevate reactive oxygen species (ROS) and cause cell death by apoptosis. Nox4 NADPH oxidase is the main Nox isoform in CMVEC and cortical astrocytes that is acutely activated by TNF-α and glutamate leading to ROS-mediated cell death by apoptosis. The Nox4 inhibitor GKT137831 blocked NADPH oxidase activity and overall ROS elevation, and prevented apoptosis of CMVEC and astrocytes exposed to TNF-α and glutamate, supporting the leading role of Nox4 in the neurovascular injury. Synthetic SFN (10-11 -10-6 mol/L) inhibited NADPH oxidase activity and reduced overall ROS production in CMVEC and astrocytes within 1-hour exposure to TNF-α and glutamate. Furthermore, in the presence of SFN, the ability of TNF-α and glutamate to produce apoptosis in CMVEC and cortical astrocytes was completely prevented. Overall, SFN at low concentrations exhibits antioxidant and antiapoptotic effects in cerebral endothelial cells and cortical astrocytes via a via a nongenomic mechanism that involves inhibition of Nox4 NADPH oxidase activity. SFN may prevent cerebrovascular injury during brain oxidative stress caused by inflammation and glutamate excitotoxicity.
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Affiliation(s)
- Jianxiong Liu
- Department of PhysiologyUniversity of Tennessee Health Science CenterMemphisTNUSA
| | - Giri K. Chandaka
- Department of PhysiologyUniversity of Tennessee Health Science CenterMemphisTNUSA
| | - Rong Zhang
- Department of PhysiologyUniversity of Tennessee Health Science CenterMemphisTNUSA
| | - Helena Parfenova
- Department of PhysiologyUniversity of Tennessee Health Science CenterMemphisTNUSA
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Liu J, Fedinec AL, Zhang R, Harsono M, Pourcyrous M, Parfenova H. The cold receptor TRPM8 activation in cerebral circulation leads to acute reversible impairment of endothelium‐dependent vasodilator function during selective head cooling. FASEB J 2020. [DOI: 10.1096/fasebj.2020.34.s1.03414] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Liu J, Hoover DT, Fedinec AL, Chandaka GK, Harsono M, Pourcyrous M, Leffler CW, Parfenova H. Phytochemical Sulforaphane Provides Cerebrovascular Protection in a Large Animal Model of Brain Oxidative Stress Injury Caused by Prolonged Neonatal Asphyxia. FASEB J 2019. [DOI: 10.1096/fasebj.2019.33.1_supplement.528.4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Patel S, Fedinec AL, Liu J, Weiss MA, Pourcyrous M, Harsono M, Parfenova H, Leffler CW. H 2S mediates the vasodilator effect of endothelin-1 in the cerebral circulation. Am J Physiol Heart Circ Physiol 2018; 315:H1759-H1764. [PMID: 30265150 DOI: 10.1152/ajpheart.00451.2018] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
H2S is an endogenous gasotransmitter that increases cerebral blood flow. In the cerebral vascular endothelium, H2S is produced by cystathionine δ-lyase (CSE). Endothelin-1 (ET-1) has constrictor and dilator influences on the cerebral circulation. The mechanism of the vasodilation caused by ET-1 may involve endothelium-derived factors. We hypothesize that ET-1-elicited dilation of pial arterioles requires an elevation of H2S production in the cerebral vascular endothelium. We investigated the effects of ET-1 on CSE-catalyzed brain H2S production and pial arteriolar diameter using cranial windows in newborn pigs in vivo. H2S was measured in periarachnoid cerebrospinal fluid. ET-1 (10-12-10-8 M) caused an elevation of H2S that was reduced by the CSE inhibitors propargylglycine (PPG) and β-cyano-l-alanine (BCA). Low doses of ET-1 (10-12-10-11 M) produced vasodilation of pial arterioles that was blocked PPG and BCA, suggesting the importance of H2S influences. The vasodilator effects of H2S may require activation of smooth muscle cell membrane ATP-sensitive K+ (KATP) channels and large-conductance Ca2+-activated K+ (BK) channels. The KATP inhibitor glibenclamide and the BK inhibitor paxilline blocked CSE/H2S-dependent dilation of pial arterioles to ET-1. In contrast, the vasoconstrictor response of pial arterioles to 10-8 M ET-1 was not modulated by PPG, BCA, glibenclamide, or paxilline and, therefore, was independent of CSE/H2S influences. Pial arteriolar constriction response to higher levels of ET-1 was independent of CSE/H2S and KATP/BKCa channel activation. These data suggest that H2S is an endothelium-derived factor that mediates the vasodilator effects of ET-1 in the cerebral circulation via a mechanism that involves activation of KATP and BK channels in vascular smooth muscle. NEW & NOTEWORTHY Disorders of the cerebral circulation in newborn infants may lead to lifelong neurological disabilities. We report that vasoactive peptide endothelin-1 exhibits vasodilator properties in the neonatal cerebral circulation by stimulating production of H2S, an endothelium-derived messenger with vasodilator properties. The ability of endothelin-1 to stimulate brain production of H2S may counteract the reduction in cerebral blood flow and prevent the cerebral vascular dysfunction caused by stroke, asphyxia, cerebral hypoxia, ischemia, and vasospasm.
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Affiliation(s)
- Shalinkumar Patel
- Division of Neonatology, Department of Pediatrics, University of Tennessee Health Science Center , Memphis, Tennessee
| | - Alexander L Fedinec
- Laboratory for Research in Neonatal Physiology, Departments of Physiology and Pediatrics, University of Tennessee Health Science Center , Memphis, Tennessee
| | - Jiangxiong Liu
- Laboratory for Research in Neonatal Physiology, Departments of Physiology and Pediatrics, University of Tennessee Health Science Center , Memphis, Tennessee
| | - Max A Weiss
- Laboratory for Research in Neonatal Physiology, Departments of Physiology and Pediatrics, University of Tennessee Health Science Center , Memphis, Tennessee
| | - Massroor Pourcyrous
- Division of Neonatology, Department of Pediatrics, University of Tennessee Health Science Center , Memphis, Tennessee.,Laboratory for Research in Neonatal Physiology, Departments of Physiology and Pediatrics, University of Tennessee Health Science Center , Memphis, Tennessee
| | - Mimily Harsono
- Division of Neonatology, Department of Pediatrics, University of Tennessee Health Science Center , Memphis, Tennessee
| | - Helena Parfenova
- Laboratory for Research in Neonatal Physiology, Departments of Physiology and Pediatrics, University of Tennessee Health Science Center , Memphis, Tennessee
| | - Charles W Leffler
- Division of Neonatology, Department of Pediatrics, University of Tennessee Health Science Center , Memphis, Tennessee.,Laboratory for Research in Neonatal Physiology, Departments of Physiology and Pediatrics, University of Tennessee Health Science Center , Memphis, Tennessee
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Parfenova H, Pourcyrous M, Fedinec AL, Liu J, Basuroy S, Leffler CW. Astrocyte-produced carbon monoxide and the carbon monoxide donor CORM-A1 protect against cerebrovascular dysfunction caused by prolonged neonatal asphyxia. Am J Physiol Heart Circ Physiol 2018; 315:H978-H988. [PMID: 30028198 DOI: 10.1152/ajpheart.00140.2018] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Neonatal asphyxia leads to cerebrovascular disease and neurological complications via a mechanism that may involve oxidative stress. Carbon monoxide (CO) is an antioxidant messenger produced via a heme oxygenase (HO)-catalyzed reaction. Cortical astrocytes are the major cells in the brain that express constitutive HO-2 isoform. We tested the hypothesis that CO, produced by astrocytes, has cerebroprotective properties during neonatal asphyxia. We developed a survival model of prolonged asphyxia in newborn pigs that combines insults of severe hypoxia, hypercapnia, and acidosis while avoiding extreme hypotension and cerebral blood flow reduction. During the 60-min asphyxia, CO production by brain and astrocytes was continuously elevated. Excessive formation of reactive oxygen species during asphyxia/reventilation was potentiated by the HO inhibitor tin protoporphyrin, suggesting that endogenous CO has antioxidant effects. Cerebral vascular outcomes tested 24 and 48 h after asphyxia demonstrated the sustained impairment of cerebral vascular responses to astrocyte- and endothelium-specific vasodilators. Postasphyxia cerebral vascular dysfunction was aggravated in newborn pigs pretreated with tin protoporphyrin to inhibit brain HO/CO. The CO donor CO-releasing molecule-A1 (CORM-A1) reduced brain oxidative stress during asphyxia/reventilation and prevented postasphyxia cerebrovascular dysfunction. The antioxidant and antiapoptotic effects of HO/CO and CORM-A1 were confirmed in primary cultures of astrocytes from the neonatal pig brain exposed to glutamate excitotoxicity. Overall, prolonged neonatal asphyxia leads to neurovascular injury via an oxidative stress-mediated mechanism that is counteracted by an astrocyte-based constitutive antioxidant HO/CO system. We propose that gaseous CO or CO donors can be used as novel approaches for prevention of neonatal brain injury caused by prolonged asphyxia. NEW & NOTEWORTHY Asphyxia in newborn infants may lead to lifelong neurological disabilities. Using the model of prolonged asphyxia in newborn piglets, we propose novel antioxidant therapy based on systemic administration of low doses of a carbon monoxide donor that prevent loss of cerebral blood flow regulation and may improve the neurological outcome of asphyxia.
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Affiliation(s)
- Helena Parfenova
- Departments of Physiology and Pediatrics, University of Tennessee Health Science Center , Memphis, Tennessee
| | - Massroor Pourcyrous
- Departments of Physiology and Pediatrics, University of Tennessee Health Science Center , Memphis, Tennessee
| | - Alex L Fedinec
- Departments of Physiology and Pediatrics, University of Tennessee Health Science Center , Memphis, Tennessee
| | - Jianxiong Liu
- Departments of Physiology and Pediatrics, University of Tennessee Health Science Center , Memphis, Tennessee
| | - Shyamali Basuroy
- Departments of Physiology and Pediatrics, University of Tennessee Health Science Center , Memphis, Tennessee
| | - Charles W Leffler
- Departments of Physiology and Pediatrics, University of Tennessee Health Science Center , Memphis, Tennessee
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Liu J, Leffler CW, Fedinec AL, Pourcyrous M, Parfenova H. Antioxidant and Cerebroprotective Roles of Carbon Monoxide (CO) Against Cerebrovascular Injury Caused by Prolonged Neonatal Asphyxia. FASEB J 2018. [DOI: 10.1096/fasebj.2018.32.1_supplement.712.4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Liu J, Pourcyrous M, Fedinec AL, Leffler CW, Parfenova H. Preventing harmful effects of epileptic seizures on cerebrovascular functions in newborn pigs: does sex matter? Pediatr Res 2017; 82:881-887. [PMID: 28665933 PMCID: PMC5645245 DOI: 10.1038/pr.2017.152] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/21/2017] [Accepted: 04/26/2017] [Indexed: 12/31/2022]
Abstract
BackgroundThe potential contribution of sex-related variables to cerebrovascular functions in neonates remains elusive. Newborn piglets provide a translationally relevant model for studying the effects of seizures in the neonatal brain. The present study investigated whether sex differences contribute to cerebrovascular functions in healthy and epileptic newborn pigs.MethodsEpileptic seizures were induced in female and male newborn pigs by bicuculline. An antioxidant drug, the carbon monoxide-releasing molecule CORM-A1, was administered enterally before or during seizures. The responses of pial arterioles to endothelium-, astrocyte-, and vascular smooth muscle-dependent vasodilators were tested in intact and 48-h postictal piglets using the cranial window technique.ResultsIn intact newborn pigs, we did not observe any sex-related differences in cerebrovascular functions. In the postictal male and female newborn pigs, a marked reduction in responses of pial arterioles to endothelium- and astrocyte-dependent vasodilators was detected. CORM-A1, administered before or during seizures, greatly improved the outcome of seizures on cerebrovascular functions in both male and female piglets.ConclusionWe found no evidence of sex-related differences in cerebral vasodilator functions in control and epileptic newborn pigs. In both male and female newborns, epileptic seizures lead to prolonged cerebral vascular dysfunction that is effectively prevented by CORM-A1 therapy.
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Affiliation(s)
| | | | | | | | - Helena Parfenova
- Correspondence: Helena Parfenova Ph.D., Department of Physiology, 956 Court Avenue Suite E332, Memphis TN 38164, Phone: 901-448-8318, Fax: 901-448-7126,
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Myers MH, Jolly E, Li Y, de Jongh Curry A, Parfenova H. Power Spectral Density Analysis of Electrocorticogram Recordings during Cerebral Hypothermia in Neonatal Seizures. Ann Neurosci 2017; 24:12-19. [PMID: 28596673 PMCID: PMC5460947 DOI: 10.1159/000464418] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2016] [Accepted: 09/11/2016] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Neonatal seizures (NS) are the most common form of neurological dysfunction observed in newborns. PURPOSE The purpose of this study in newborn piglets was to determine the effect of cerebral hypothermia (CH) on neural activity during pharmacologically induced NS. We hypothesized that the neuroprotective effects of CH would preserve higher frequencies observed in electrocorticogram (ECoG) recordings. METHODS Power spectral density was employed to determine the levels of brain activity in ECoGs to quantitatively assess the power of each frequency observed in neurological brain states of delta, theta, alpha, and beta-gamma frequencies. RESULT The most significant reduction of power occurs in the lower frequency band of delta-theta-alpha of CH cohorts, while t score probabilities imply that high-frequency brain activity in the beta-gamma range is preserved in the CH population. CONCLUSION While the overall power density decreases over time in both groups, the decrease is to a lesser degree in the CH population.
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Affiliation(s)
- Mark H. Myers
- Department of Anatomy and Neurobiology, University of Tennessee Health Science Center Memphis, Memphis, TN, USA
| | - Elliott Jolly
- Department of Biomedical Engineering, University of Memphis, Memphis, TN, USA
| | - Yaqin Li
- Department of Ophthalmology, University of Tennessee Health Science Center, Memphis, TN, USA
| | - Amy de Jongh Curry
- Department of Biomedical Engineering, University of Memphis, Memphis, TN, USA
| | - Helena Parfenova
- Department of Physiology, University of Tennessee Health Science Center, Memphis, TN, USA
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Harsono M, Pourcyrous M, Jolly EJ, de Jongh Curry A, Fedinec AL, Liu J, Basuroy S, Zhuang D, Leffler CW, Parfenova H. Selective head cooling during neonatal seizures prevents postictal cerebral vascular dysfunction without reducing epileptiform activity. Am J Physiol Heart Circ Physiol 2016; 311:H1202-H1213. [PMID: 27591217 DOI: 10.1152/ajpheart.00227.2016] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/11/2016] [Accepted: 08/22/2016] [Indexed: 01/12/2023]
Abstract
Epileptic seizures in neonates cause cerebrovascular injury and impairment of cerebral blood flow (CBF) regulation. In the bicuculline model of seizures in newborn pigs, we tested the hypothesis that selective head cooling prevents deleterious effects of seizures on cerebral vascular functions. Preventive or therapeutic ictal head cooling was achieved by placing two head ice packs during the preictal and/or ictal states, respectively, for the ∼2-h period of seizures. Head cooling lowered the brain and core temperatures to 25.6 ± 0.3 and 33.5 ± 0.1°C, respectively. Head cooling had no anticonvulsant effects, as it did not affect the bicuculline-evoked electroencephalogram parameters, including amplitude, duration, spectral power, and spike frequency distribution. Acute and long-term cerebral vascular effects of seizures in the normothermic and head-cooled groups were tested during the immediate (2-4 h) and delayed (48 h) postictal periods. Seizure-induced cerebral vascular injury during the immediate postictal period was detected as terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling-positive staining of cerebral arterioles and a surge of brain-derived circulating endothelial cells in peripheral blood in the normothermic group, but not in the head-cooled groups. During the delayed postictal period, endothelium-dependent cerebral vasodilator responses were greatly reduced in the normothermic group, indicating impaired CBF regulation. Preventive or therapeutic ictal head cooling mitigated the endothelial injury and greatly reduced loss of postictal cerebral vasodilator functions. Overall, head cooling during seizures is a clinically relevant approach to protecting the neonatal brain by preventing cerebrovascular injury and the loss of the endothelium-dependent control of CBF without reducing epileptiform activity.
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Affiliation(s)
- Mimily Harsono
- Department of Physiology, University of Tennessee Health Science Center, Memphis, Tennessee; and
| | - Massroor Pourcyrous
- Department of Physiology, University of Tennessee Health Science Center, Memphis, Tennessee; and
| | - Elliott J Jolly
- Department of Biomedical Engineering, University of Memphis, Memphis, Tennessee
| | - Amy de Jongh Curry
- Department of Biomedical Engineering, University of Memphis, Memphis, Tennessee
| | - Alexander L Fedinec
- Department of Physiology, University of Tennessee Health Science Center, Memphis, Tennessee; and
| | - Jianxiong Liu
- Department of Physiology, University of Tennessee Health Science Center, Memphis, Tennessee; and
| | - Shyamali Basuroy
- Department of Physiology, University of Tennessee Health Science Center, Memphis, Tennessee; and
| | - Daming Zhuang
- Department of Physiology, University of Tennessee Health Science Center, Memphis, Tennessee; and
| | - Charles W Leffler
- Department of Physiology, University of Tennessee Health Science Center, Memphis, Tennessee; and
| | - Helena Parfenova
- Department of Physiology, University of Tennessee Health Science Center, Memphis, Tennessee; and
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15
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Liu J, Leffler C, Parfenova H. Hydrogen Sulfide Is An Endogenous Cytoprotective Gaseous Mediator in Cerebral Circulation. FASEB J 2015. [DOI: 10.1096/fasebj.29.1_supplement.645.4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Jianxiong Liu
- PhysiologyUniversity of Tennessee HSCMemphisTNUnited States
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16
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Pourcyrous M, Basuroy S, Tcheranova D, Arheart KL, Elabiad MT, Leffler CW, Parfenova H. Brain-derived circulating endothelial cells in peripheral blood of newborn infants with seizures: a potential biomarker for cerebrovascular injury. Physiol Rep 2015; 3:3/3/e12345. [PMID: 25804265 PMCID: PMC4393173 DOI: 10.14814/phy2.12345] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Neonatal seizures have been associated with cerebrovascular endothelial injury and neurological disabilities. In a piglet model, the long-term loss of endothelial regulation of cerebral blood flow coincides with the surge of brain-derived circulating endothelial cells (BCECs) in blood. We hypothesized that BCECs could serve as a noninvasive biomarker of cerebrovascular injury in neonates with seizures. In a prospective pilot feasibility study, we enrolled newborn infants with confirmed diagnoses of perinatal asphyxia and intraventricular hemorrhage (IVH); both are commonly associated with seizures. Infants without clinical evidence of cerebrovascular injuries were representative of the control group. BCECs were detected in the CD45-negative fraction of peripheral blood mononuclear cells by coexpression of CD31 (common endothelial antigen) and GLUT1 (blood-brain barrier antigen) via automated flow cytometry method. In Infants with asphyxia (n = 12) and those with IVH grade III/IV (n = 5), the BCEC levels were 9.9 ± 0.9% and 19.0 ± 2.0%, respectively. These levels were significantly higher than the control group (n = 27), 0.9 ± 0.2%, P < 0.001. BCECs in infants with cerebrovascular insults with documented clinical seizures (n = 10; 16.8 ± 1.3%) were significantly higher than infants with cerebrovascular insults with subclinical or no seizures (n = 7; 9.5 ± 1.2%); P < 0.001. BCEC levels decreased with seizure control. BCECs levels were elevated in infants with seizures caused by severe IVH and perinatal asphyxia. We suggest that monitoring BCEC levels in peripheral blood can potentially offer a biological marker that reflects cerebrovascular insult and recovery. Further studies with a larger number of patients are required to support these findings.
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Affiliation(s)
- Massroor Pourcyrous
- Department of Pediatrics, The University of Tennessee Health Science Center (UTHSC), Memphis, Tennessee Department of Physiology, The University of Tennessee Health Science Center (UTHSC), Memphis, Tennessee Department of Neuroscience Institute, The University of Tennessee Health Science Center (UTHSC), Memphis, Tennessee Department of Obstetrics and Gynecology, The University of Tennessee Health Science Center (UTHSC), Memphis, Tennessee
| | - Shyamali Basuroy
- Department of Physiology, The University of Tennessee Health Science Center (UTHSC), Memphis, Tennessee
| | - Dilyara Tcheranova
- Department of Physiology, The University of Tennessee Health Science Center (UTHSC), Memphis, Tennessee
| | - Kristopher L Arheart
- Division of Biostatistics and Pediatrics, Department of Public Health Sciences, Miller School of Medicine University of Miami, Coral Gables, Florida
| | - Mohamad T Elabiad
- Department of Pediatrics, The University of Tennessee Health Science Center (UTHSC), Memphis, Tennessee
| | - Charles W Leffler
- Department of Pediatrics, The University of Tennessee Health Science Center (UTHSC), Memphis, Tennessee Department of Physiology, The University of Tennessee Health Science Center (UTHSC), Memphis, Tennessee Department of Neuroscience Institute, The University of Tennessee Health Science Center (UTHSC), Memphis, Tennessee
| | - Helena Parfenova
- Department of Physiology, The University of Tennessee Health Science Center (UTHSC), Memphis, Tennessee Department of Neuroscience Institute, The University of Tennessee Health Science Center (UTHSC), Memphis, Tennessee
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17
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Liu J, Fedinec AL, Leffler CW, Parfenova H. Enteral supplements of a carbon monoxide donor CORM-A1 protect against cerebrovascular dysfunction caused by neonatal seizures. J Cereb Blood Flow Metab 2015; 35:193-9. [PMID: 25370858 PMCID: PMC4426744 DOI: 10.1038/jcbfm.2014.196] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/12/2014] [Revised: 10/02/2014] [Accepted: 10/15/2014] [Indexed: 11/09/2022]
Abstract
Cerebral blood flow dysregulation caused by oxidative stress contributes to adverse neurologic outcome of seizures. A carbon monoxide (CO) donor CORM-A1 has antioxidant and cytoprotective properties. We investigated whether enteral supplements of CORM-A1 can improve cerebrovascular outcome of bicuculline-induced seizures in newborn piglets. CORM-A1 (2 mg/kg) was given to piglets via an oral gastric tube 10 minutes before or 20 minutes after seizure onset. Enteral CORM-A1 elevated CO in periarachnoid cerebrospinal fluid and produced a dilation of pial arterioles. Postictal cerebral vascular responses to endothelium-, astrocyte-, and vascular smooth muscle-dependent vasodilators were tested 48 hours after seizures by intravital microscopy. The postictal responses of pial arterioles to bradykinin, glutamate, the AMPA receptor agonist quisqualic acid, ADP, and heme were greatly reduced, suggesting that seizures cause injury to endothelial and astrocyte components of the neurovascular unit. In contrast, in the two groups of piglets receiving enteral CORM-A1, the postictal cerebral vascular responsiveness to these dilators was improved. Overall, enteral supplements of CORM-A1 before or during seizures offer a novel effective therapeutic option to deliver cytoprotective mediator CO to the brain, reduce injury to endothelial and astrocyte components of cerebral blood flow regulation and to improve the cerebrovascular outcome of neonatal seizures.
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Affiliation(s)
- Jianxiong Liu
- Department of Physiology, University of Tennessee Health Science Center, Memphis, Tennessee, USA
| | - Alexander L Fedinec
- Department of Physiology, University of Tennessee Health Science Center, Memphis, Tennessee, USA
| | - Charles W Leffler
- Department of Physiology, University of Tennessee Health Science Center, Memphis, Tennessee, USA
| | - Helena Parfenova
- Department of Physiology, University of Tennessee Health Science Center, Memphis, Tennessee, USA
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18
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Nnorom CC, Davis C, Fedinec AL, Howell K, Jaggar JH, Parfenova H, Pourcyrous M, Leffler CW. Contributions of KATP and KCa channels to cerebral arteriolar dilation to hypercapnia in neonatal brain. Physiol Rep 2014; 2:2/8/e12127. [PMID: 25168876 PMCID: PMC4246596 DOI: 10.14814/phy2.12127] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Mechanisms by which Pco2 controls cerebral vascular tone remain uncertain. We hypothesize that potassium channel activation contributes to the neonatal cerebrovascular dilation in response to increases in Paco2. To test this hypothesis, experiments were performed on newborn pigs with surgically implanted, closed cranial windows. Hypercapnia was induced by ventilation with elevated Pco2 gas in the absence and presence of the KATP channel inhibitor, glibenclamide and/or the KCa channel inhibitor, paxillin. Dilations to pinacidil, a selective KATP channel activator, without and with glibenclamide, were used to evaluate the efficacy of KATP channel inhibition. Dilations to NS1619, a selective KCa channel activator, without and with paxillin, were used to evaluate the efficacy of KCa channel inhibition. Cerebrovascular responses to the KATP and KCa channel activators, pinacidil and NS1619, respectively, cAMP‐dependent dilator, isoproterenol, and cGMP‐dependent dilator, sodium nitroprusside (SNP), were used to evaluate the selectivity of glibenclamide and paxillin. Glibenclamide blocked dilation to pinacidil, but did not inhibit dilations to NS1619, isoproterenol, or SNP. Glibenclamide prior to hypercapnia decreased mean pial arteriole dilation ~60%. Glibenclamide treatment during hypercapnia constricted arterioles ~35%. The level of hypercapnia, Paco2 between 50 and 75 mmHg, did not appear to be involved in efficacy of glibenclamide in blocking dilation to Paco2. Similarly to glibenclamide and KATP channel inhibition, paxillin blocked dilation to the KCa channel agonist, NS1619, and attenuated, but did not block, arteriolar dilation to hypercapnia. Treatment with both glibenclamide and paxillin abolished dilation to hypercapnia. Therefore, either glibenclamide or paxillin that block dilation to their channel agonists, pinacidil or NS1619, respectively, only partially inhibit dilation to hypercapnia. Block of both KATP and KCa channels completely prevent dilation hypercapnia. These data suggest hypercapnia activates both KATP and KCa channels leading to cerebral arteriolar dilation in newborn pigs. Mechanisms by which Pco2 controls vascular tone remain uncertain. We hypothesize KATP and KCa channel activation contributes to the neonatal cerebrovascular dilation in response to increases in Paco2. Presented data support this hypothesis.
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Affiliation(s)
- Chukwuma C Nnorom
- Departments of Physiology and Pediatrics, University of Tennessee Health Science Center, Memphis, Tennessee
| | - Corinne Davis
- Departments of Physiology and Pediatrics, University of Tennessee Health Science Center, Memphis, Tennessee
| | - Alexander L Fedinec
- Departments of Physiology and Pediatrics, University of Tennessee Health Science Center, Memphis, Tennessee
| | - Khadesia Howell
- Departments of Physiology and Pediatrics, University of Tennessee Health Science Center, Memphis, Tennessee
| | - Jonathan H Jaggar
- Departments of Physiology and Pediatrics, University of Tennessee Health Science Center, Memphis, Tennessee
| | - Helena Parfenova
- Departments of Physiology and Pediatrics, University of Tennessee Health Science Center, Memphis, Tennessee
| | - Massroor Pourcyrous
- Departments of Physiology and Pediatrics, University of Tennessee Health Science Center, Memphis, Tennessee
| | - Charles W Leffler
- Departments of Physiology and Pediatrics, University of Tennessee Health Science Center, Memphis, Tennessee
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19
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Basuroy S, Leffler CW, Parfenova H. CORM-A1 prevents blood-brain barrier dysfunction caused by ionotropic glutamate receptor-mediated endothelial oxidative stress and apoptosis. Am J Physiol Cell Physiol 2013; 304:C1105-15. [PMID: 23576575 DOI: 10.1152/ajpcell.00023.2013] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
In cerebral microvascular endothelial cells (CMVEC) of newborn pigs, glutamate at excitotoxic concentrations (mM) causes apoptosis mediated by reactive oxygen species (ROS). Carbon monoxide (CO) produced by CMVEC or delivered by a CO-releasing molecule, CORM-A1, has antioxidant properties. We tested the hypothesis that CORM-A1 prevents cerebrovascular endothelial barrier dysfunction caused by glutamate excitotoxicity. First, we identified the glutamate receptors (GluRs) and enzymatic sources of ROS involved in the mechanism of endothelial apoptosis. In glutamate-exposed CMVEC, ROS formation and apoptosis were blocked by rotenone, 2-thenoyltrifluoroacetone (TTFA), and antimycin, indicating that mitochondrial complexes I, II, and III are the major sources of oxidative stress. Agonists of ionotropic GluRs (iGluRs) N-methyl-D-aspartate (NMDA), cis-ACPD, AMPA, and kainate increased ROS production and apoptosis, whereas iGluR antagonists exhibited antiapoptotic properties, suggesting that iGluRs mediate glutamate-induced endothelial apoptosis. The functional consequences of endothelial injury were tested in the model of blood-brain barrier (BBB) composed of CMVEC monolayer on semipermeable membranes. Glutamate and iGluR agonists reduced transendothelial electrical resistance and increased endothelial paracellular permeability to 3-kDa dextran. CORM-A1 exhibited potent antioxidant and antiapoptotic properties in CMVEC and completely prevented BBB dysfunction caused by glutamate and iGluR agonists. Overall, the endothelial component of the BBB is a cellular target for excitotoxic glutamate that, via a mechanism involving a iGluR-mediated activation of mitochondrial ROS production and apoptosis, leads to BBB opening that may be prevented by the antioxidant and antiapoptotic actions of CORMs. Antioxidant CORMs therapy may help preserve BBB functional integrity in neonatal cerebrovascular disease.
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Affiliation(s)
- Shyamali Basuroy
- Department of Physiology, University of Tennessee Health Science Center, Memphis, TN 38163, USA
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20
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Parfenova H, Harsono M, Liu J, Basuroy S, Jolly EJ, Jongh Curry A, Zhuang D, Leffler CW, Pourcyrous M. Cerebroprotective effects of selective head cooling during epileptic seizures. FASEB J 2013. [DOI: 10.1096/fasebj.27.1_supplement.700.1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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21
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Parfenova H, Pestina T, Persons D, Basuroy S. In vitro modeling of inflammation‐induced blood‐brain barrier dysfunction in sickle cell disease. FASEB J 2013. [DOI: 10.1096/fasebj.27.1_supplement.1121.1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
| | - Tamara Pestina
- HematologySt. Jude Children's Research HospitalMemphisTN
| | - Derek Persons
- HematologySt. Jude Children's Research HospitalMemphisTN
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22
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Parfenova H, Leffler CW, Basuroy S, Fedinec AL. Antioxidant roles of heme oxygenase, carbon monoxide and bilirubin in cerebral circulation during epileptic seizures. FASEB J 2012. [DOI: 10.1096/fasebj.26.1_supplement.685.24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Helena Parfenova
- PhysiologyUniversity of Tennessee Health Science CenterMemphisTN
| | | | - Shyamali Basuroy
- PhysiologyUniversity of Tennessee Health Science CenterMemphisTN
| | - Alex L. Fedinec
- PhysiologyUniversity of Tennessee Health Science CenterMemphisTN
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23
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Parfenova H, Tcheranova D, Basuroy S, Fedinec AL, Liu J, Leffler CW. Functional role of astrocyte glutamate receptors and carbon monoxide in cerebral vasodilation response to glutamate. Am J Physiol Heart Circ Physiol 2012; 302:H2257-66. [PMID: 22467311 DOI: 10.1152/ajpheart.01011.2011] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In newborn pigs, vasodilation of pial arterioles in response to glutamate is mediated via carbon monoxide (CO), a gaseous messenger endogenously produced from heme degradation by a heme oxygenase (HO)-catalyzed reaction. We addressed the hypothesis that ionotropic glutamate receptors (iGluRs), including N-methyl-D-aspartic acid (NMDA)- and 2-amino-3-(5-methyl-3-oxo-1,2-oxazol-4-yl) propanoic acid (AMPA)/kainate-type receptors, expressed in cortical astrocytes mediate glutamate-induced astrocyte HO activation that leads to cerebral vasodilation. Acute vasoactive effects of topical iGluR agonists were determined by intravital microscopy using closed cranial windows in anesthetized newborn pigs. iGluR agonists, including NMDA, (±)1-aminocyclopentane-cis-1,3-dicarboxylic acid (cis-ACPD), AMPA, and kainate, produced pial arteriolar dilation. Topical L-2-aminoadipic acid, a gliotoxin that selectively disrupts glia limitans, reduced vasodilation caused by iGluR agonists, but not by hypercapnia, bradykinin, or sodium nitroprusside. In freshly isolated and cultured cortical astrocytes constitutively expressing HO-2, iGluR agonists NMDA, cis-ACPD, AMPA, and kainate rapidly increased CO production two- to threefold. Astrocytes overexpressing inducible HO-1 had high baseline CO but were less sensitive to glutamate stimulation of CO production when compared with HO-2-expressing astrocytes. Glutamate-induced astrocyte HO-2-mediated CO production was inhibited by either the NMDA receptor antagonist (R)-3C4HPG or the AMPA/kainate receptor antagonist DNQX. Accordingly, either antagonist abolished pial arteriolar dilation in response to glutamate, NMDA, and AMPA, indicating functional interaction among various subtypes of astrocytic iGluRs in response to glutamate stimulation. Overall, these data indicate that the astrocyte component of the neurovascular unit is responsible for the vasodilation response of pial arterioles to topically applied glutamate via iGluRs that are functionally linked to activation of constitutive HO in newborn piglets.
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Affiliation(s)
- Helena Parfenova
- Department of Physiology, University of Tennessee Health Science Center, Memphis, 38163, USA.
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24
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Xi Q, Tcheranova D, Basuroy S, Parfenova H, Jaggar JH, Leffler CW. Glutamate-induced calcium signals stimulate CO production in piglet astrocytes. Am J Physiol Heart Circ Physiol 2011; 301:H428-33. [PMID: 21572018 DOI: 10.1152/ajpheart.01277.2010] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Glutamate-stimulated, astrocyte-derived carbon monoxide (CO) causes cerebral arteriole dilation by activating smooth muscle cell large-conductance Ca(2+)-activated K(+) channels. Here, we examined the hypothesis that glutamate activates heme oxygenase (HO)-2 and CO production via the intracellular Ca(2+) concentration ([Ca(2+)](i))/Ca(2+)-calmodulin signaling pathway in newborn pig astrocytes. The major findings are: 1) glutamate stimulated Ca(2+) transients and increased steady-state [Ca(2+)](i) in cerebral cortical astrocytes in primary culture, 2) in astrocytes permeabilized with ionomycin, elevation of [Ca(2+)](i) concentration-dependently increased CO production, 3) glutamate did not affect CO production at any [Ca(2+)](i) when the [Ca(2+)](i) was held constant, 4) thapsigargin, a sarco/endoplasmic reticulum Ca(2+)-ATPase blocker, decreased basal CO production and blocked glutamate-induced increases in CO, and 5) calmidazolium, a calmodulin inhibitor, blocked CO production induced by glutamate and by [Ca(2+)](i) elevation. Taken together, our data are consistent with the hypothesis that glutamate elevates [Ca(2+)](i) in astrocytes, leading to Ca(2+)- and calmodulin-dependent HO-2 activation, and CO production.
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Affiliation(s)
- Qi Xi
- Laboratory for Research in Neonatal Physiology, Department of Physiology, University of Tennessee Health Science Center, Memphis, Tennessee 38163, USA
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25
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Abstract
Carbon monoxide (CO) is produced by heme oxygenase (HO)-catalyzed heme degradation to CO, iron, and biliverdin. HO has two active isoforms, HO-1 (inducible) and HO-2 (constitutive). HO-2, but not HO-1, is highly expressed in endothelial and smooth muscle cells and in adjacent astrocytes in the brain. HO-1 is expressed basally only in the spleen and liver but can be induced to a varying extent in most tissues. Elevating heme, protein phosphorylation, Ca(2+) influx, and Ca(2+)/calmodulin-dependent processes increase HO-2 activity. CO dilates cerebral arterioles and may constrict or dilate skeletal muscle and renal arterioles. Selected vasodilatory stimuli, including seizures, glutamatergic stimulation, hypoxia, hypotension, and ADP, increase CO, and the inhibition of HO attenuates the dilation to these stimuli. Astrocytic HO-2-derived CO causes glutamatergic dilation of pial arterioles. CO dilates by activating smooth muscle cell large-conductance Ca(2+)-activated K(+) (BK(Ca)) channels. CO binds to BK(Ca) channel-bound heme, leading to an increase in Ca(2+) sparks-to-BK(Ca) channel coupling. Also, CO may bind directly to the BK(Ca) channel at several locations. Endothelial nitric oxide and prostacyclin interact with HO/CO in circulatory regulation. In cerebral arterioles in vivo, in contrast to dilation to acute CO, a prolonged exposure of cerebral arterioles to elevated CO produces progressive constriction by inhibiting nitric oxide synthase. The HO/CO system is highly protective to the vasculature. CO suppresses apoptosis and inhibits components of endogenous oxidant-generating pathways. Bilirubin is a potent reactive oxygen species scavenger. Still many questions remain about the physiology and biochemistry of HO/CO in the circulatory system and about the function and dysfunction of this gaseous mediator system.
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26
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Xi Q, Parfenova H, Jaggar JH, Leffler CW. BK
Ca
channels modulate cortical astrocytic CO production in newborn pigs. FASEB J 2011. [DOI: 10.1096/fasebj.25.1_supplement.1023.17] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Qi Xi
- Department of PhysiologyThe University of Tennessee Health Science CenterMemphisTN
| | - Helena Parfenova
- Department of PhysiologyThe University of Tennessee Health Science CenterMemphisTN
| | - Jonathan H. Jaggar
- Department of PhysiologyThe University of Tennessee Health Science CenterMemphisTN
| | - Charles W. Leffler
- Department of PhysiologyThe University of Tennessee Health Science CenterMemphisTN
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27
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Leffler CW, Parfenova H, Basuroy S, Jaggar JH, Umstot ES, Fedinec AL. Hydrogen sulfide and cerebral microvascular tone in newborn pigs. Am J Physiol Heart Circ Physiol 2011; 300:H440-7. [PMID: 21131483 PMCID: PMC3044062 DOI: 10.1152/ajpheart.00722.2010] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/21/2010] [Accepted: 11/22/2010] [Indexed: 11/22/2022]
Abstract
Hydrogen sulfide (H2S) is a gaseous signaling molecule that appears to be involved in numerous biological processes, including regulation of blood pressure and vascular tone. The present study is designed to address the hypothesis that H2S is a functionally significant, endogenous dilator in the newborn cerebrovascular circulation. In vivo experiments were conducted using newborn pigs with surgically implanted, closed, cranial windows. Topical application of H2S concentration-dependently (10(-6) to 2×10(-4) M) dilated pial arterioles. This dilation was blocked by glibenclamide (10(-6) M). L-cysteine, the substrate of the H2S-producing enzymes cystathionine γ-lyase (CSE) and cystathionine β-synthase (CBS), also dilated pial arterioles. The dilation to L-cysteine was blocked by the CSE inhibitor d,l-propargylglycine (PPG, 10 mM) but was unaffected by the CBS inhibitor amino-oxyacetate (AOA, 1 mM). Western blots detected CSE, but not CBS, in cerebral microvessels, whereas CBS is detected in brain parenchyma. Immunohistological CSE expression is predominantly vascular while CBS is expressed mainly in neurons and astrocytes. L-cysteine (5 mM) increased H2S concentration in cerebrospinal fluid (CSF), measured by GC-MS, from 561±205 to 2,783±818 nM before but not during treatment with PPG (1,030±70 to 622±78 nM). Dilation to hypercapnia was inhibited by PPG but not AOA. Hypercapnia increased CSF H2S concentration from 763±243 to 4,337±1789 nM before but not during PPG treatment (357±178 vs. 425±217 nM). These data show that H2S is a dilator of the newborn cerebral circulation and that endogenous CSE can produce sufficient H2S to decrease vascular tone. H2S appears to be a physiologically significant dilator in the cerebral circulation.
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Affiliation(s)
- Charles W Leffler
- Laboratory for Research in Neonatal Physiology, Department of Physiology, University of Tennessee Health Science Center, 894 Union Ave., Memphis, TN 38163, USA.
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28
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Basuroy S, Tcheranova D, Bhattacharya S, Leffler CW, Parfenova H. Nox4 NADPH oxidase-derived reactive oxygen species, via endogenous carbon monoxide, promote survival of brain endothelial cells during TNF-α-induced apoptosis. Am J Physiol Cell Physiol 2010; 300:C256-65. [PMID: 21123734 DOI: 10.1152/ajpcell.00272.2010] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
We investigated the role of reactive oxygen species (ROS) in promoting cell survival during oxidative stress induced by the inflammatory mediator tumor necrosis factor-α (TNF-α) in cerebral microvascular endothelial cells (CMVEC) from newborn piglets. Nox4 is the major isoform of NADPH oxidase responsible for TNF-α-induced oxidative stress and apoptosis in CMVEC. We present novel data that Nox4 NADPH oxidase-derived ROS also initiate a cell survival mechanism by increasing production of a gaseous antioxidant mediator carbon monoxide (CO) by constitutive heme oxygenase-2 (HO-2). TNF-α rapidly enhanced endogenous CO production in a superoxide- and NADPH oxidase-dependent manner in CMVEC with innate, but not with small interfering RNA (siRNA)-downregulated Nox4 activity. CORM-A1, a CO-releasing compound, inhibited Nox4-mediated ROS production and enhanced cell survival in TNF-α-challenged CMVEC. The ROS-induced CO-mediated survival mechanism requires functional interactions between the protein kinase B/Akt and extracellular signal-related kinase (ERK)/p38 MAPK signaling pathways activated by TNF-α. In Akt siRNA-transfected CMVEC and in cells with pharmacologically inhibited Akt, Erk1/2, and p38 mitogen-activated protein kinase (MAPK) activities, CORM-A1 was no longer capable of blocking Nox4 activation and apoptosis caused by TNF-α. Overall, Nox4 NADPH oxidase-derived ROS initiate both death and survival pathways in TNF-α-challenged CMVEC. The ROS-dependent cell survival pathway is mediated by an endogenous antioxidant CO, which inhibits Nox4 activation via a mechanism that includes Akt, ERK1/2, and p38 MAPK signaling pathways. The ability of CO to inhibit TNF-α-induced ERK1/2 and p38 MAPK activities in an Akt-dependent manner appears to be the key element in ROS-dependent survival of endothelial cells during TNF-α-mediated brain inflammatory disease.
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Affiliation(s)
- Shyamali Basuroy
- Dept. of Physiology, University of Tennessee Health Science Center, 894 Union Ave., Memphis, TN 38163, USA
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29
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Parfenova H, Leffler CW, Tcheranova D, Basuroy S, Zimmermann A. Epileptic seizures increase circulating endothelial cells in peripheral blood as early indicators of cerebral vascular damage. Am J Physiol Heart Circ Physiol 2010; 298:H1687-98. [PMID: 20363895 DOI: 10.1152/ajpheart.00032.2010] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Circulating endothelial cells (CECs) are nonhematopoetic mononuclear cells in peripheral blood that are dislodged from injured vessels during cardiovascular disease, systemic vascular disease, and inflammation. Their occurrence during cerebrovascular insults has not been previously described. Epileptic seizures cause the long-term loss of cerebrovascular endothelial dilator function. We hypothesized that seizures cause endothelial sloughing from cerebral vessels and the appearance of brain-derived CECs (BCECs), possible early indicators of cerebral vascular damage. Epileptic seizures were induced by bicuculline in newborn pigs; venous blood was then sampled during a 4-h period. CECs were identified in the fraction of peripheral blood mononuclear cells by the expression of endothelial antigens (CD146, CD31, and endothelial nitric oxide synthase) and by Ulex europeaus lectin binding. In control animals, few CECs were detected. Seizures caused a time-dependent increase in CECs 2-4 h after seizure onset. Seizure-induced CECs coexpress glucose transporter-1, a blood-brain barrier-specific glucose transporter, indicating that these cells originate in the brain vasculature and are thus BCECs. Seizure-induced BCECs cultured in EC media exhibited low proliferative potential and abnormal cell contacts. BCEC appearance during seizures was blocked by a CO-releasing molecule (CORM-A1) or cobalt protoporphyrin (heme oxygenase-1 inducer), which prevented apoptosis in cerebral arterioles and the loss of cerebral vascular endothelial function during the late postictal period. These findings suggest that seizure-induced BCECs are injured ECs dislodged from cerebral microvessels during seizures. The correlation between the appearance of BCECs in peripheral blood, apoptosis in cerebral vessels, and the loss of postictal cerebral vascular function suggests that BCECs are early indicators of late cerebral vascular damage.
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Affiliation(s)
- Helena Parfenova
- Dept. of Physiology, Univ. of Tennessee Health Science Center, 894 Union Ave., Memphis, TN 38163, USA.
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Xi Q, Tcheranova D, Basuroy S, Parfenova H, Jaggar JH, Leffler CW. Glutamate‐stimulated, astrocyte‐derived carbon monoxide production is intracellular calcium concentration‐dependent in piglets. FASEB J 2010. [DOI: 10.1096/fasebj.24.1_supplement.lb556] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Qi Xi
- PhysiologyThe University of Tennessee Health Science CenterMemphisTN
| | | | - Shyamali Basuroy
- PhysiologyThe University of Tennessee Health Science CenterMemphisTN
| | - Helena Parfenova
- PhysiologyThe University of Tennessee Health Science CenterMemphisTN
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Basuroy S, Bhattacharya S, Leffler CW, Parfenova H. Akt/Bcl‐2 signaling is critical for anti‐apoptotic effects of carbon monoxide (CO) against TNF‐alpha‐mediated inflammatory damage in cerebral vascular endothelial cells. FASEB J 2010. [DOI: 10.1096/fasebj.24.1_supplement.979.8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Shyamali Basuroy
- PhysiologyUniversity of Tennessee Health Science CenterMemphisTN
| | | | | | - Helena Parfenova
- PhysiologyUniversity of Tennessee Health Science CenterMemphisTN
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Parfenova H, Basuroy S, Fedinec A, Leffler CW. Carbon monoxide inhibits NADPH oxidase activation during seizures and prevents loss of postictal cerebral vascular function. FASEB J 2009. [DOI: 10.1096/fasebj.23.1_supplement.613.4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Basuroy S, Bhattacharya S, Leffler CW, Parfenova H. Nox4 NADPH oxidase mediates oxidative stress and apoptosis caused by TNF‐alpha in cerebral vascular endothelial cells. FASEB J 2009. [DOI: 10.1096/fasebj.23.1_supplement.613.2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Shyamali Basuroy
- PhysiologyUniversity of Tennessee Health Science CenterMemphisTN
| | | | | | - Helena Parfenova
- PhysiologyUniversity of Tennessee Health Science CenterMemphisTN
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Pourcyrous M, Tcheranova D, Basuroy S, Leffler CW, Parfenova H. Detection of brain‐derived circulating endothelial cells in peripheral blood of newborn infants with cerebrovascular disorders. FASEB J 2009. [DOI: 10.1096/fasebj.23.1_supplement.613.6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Basuroy S, Bhattacharya S, Leffler CW, Parfenova H. Nox4 NADPH oxidase mediates oxidative stress and apoptosis caused by TNF-alpha in cerebral vascular endothelial cells. Am J Physiol Cell Physiol 2008; 296:C422-32. [PMID: 19118162 DOI: 10.1152/ajpcell.00381.2008] [Citation(s) in RCA: 190] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Inflammatory brain disease may damage cerebral vascular endothelium leading to cerebral blood flow dysregulation. The proinflammatory cytokine TNF-alpha causes oxidative stress and apoptosis in cerebral microvascular endothelial cells (CMVEC) from newborn pigs. We investigated contribution of major cellular sources of reactive oxygen species to endothelial inflammatory response. Nitric oxide synthase and xanthine oxidase inhibitors (N(omega)-nitro-l-arginine and allopurinol) had no effect, while mitochondrial electron transport inhibitors (CCCP, 2-thenoyltrifluoroacetone, and rotenone) attenuated TNF-alpha-induced superoxide (O(2)(*-)) and apoptosis. NADPH oxidase inhibitors (diphenylene iodonium and apocynin) greatly reduced TNF-alpha-evoked O(2)(*-) generation and apoptosis. TNF-alpha rapidly increased NADPH oxidase activity in CMVEC. Nox4, the cell-specific catalytic subunit of NADPH oxidase, is highly expressed in CMVEC, contributes to basal O(2)(*-) production, and accounts for a burst of oxidative stress in response to TNF-alpha. Nox4 small interfering RNA, but not Nox2, knockdown prevented oxidative stress and apoptosis caused by TNF-alpha in CMVEC. Nox4 is colocalized with HO-2, the constitutive isoform of heme oxygenase (HO), which is critical for endothelial protection against TNF-alpha toxicity. The products of HO activity, bilirubin and carbon monoxide (CO, as a CO-releasing molecule, CORM-A1), inhibited Nox4-generated O(2)(*-) and apoptosis caused by TNF-alpha stimulation. We conclude that Nox4 is the primary source of inflammation- and TNF-alpha-induced oxidative stress leading to apoptosis in brain endothelial cells. The ability of CO and bilirubin to combat TNF-alpha-induced oxidative stress by inhibiting Nox4 activity and/or by O(2)(*-) scavenging, taken together with close intracellular compartmentalization of HO-2 and Nox4 in cerebral vascular endothelium, may contribute to HO-2 cytoprotection against inflammatory cerebrovascular disease.
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Affiliation(s)
- Shyamali Basuroy
- Dept. of Physiology, Univ. of Tennessee Health Science Center, 894 Union Ave., Memphis, TN 38163, USA.
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Tcheranova D, Parfenova H, Leffler CW. Ca
2+
signaling in glutamate‐stimulated CO production by newborn pig astrocytes. FASEB J 2008. [DOI: 10.1096/fasebj.22.1_supplement.1151.10] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Abstract
The constitutive isoform of heme oxygenase, HO-2, is highly expressed in the brain and in cerebral vessels. HO-2 functions in the brain have been evaluated using pharmacological inhibitors of the enzyme and HO-2 gene deletion in in vivo animal models and in cultured cells (neurons, astrocytes, cerebral vascular endothelial cells). Rapid activation of HO-2 via post-translational modifications without upregulation of HO-2 expression or HO-1 induction coincides with the increase in cerebral blood flow aimed at maintaining brain homeostasis and neuronal survival during seizures, hypoxia, and hypotension. Pharmacological inhibition or gene deletion of brain HO-2 exacerbates oxidative stress induced by seizures, glutamate, and inflammatory cytokines, and causes cerebral vascular injury. Carbon monoxide (CO) and bilirubin, the end products of HO-catalyzed heme degradation, have distinct cytoprotective functions. CO, by binding to a heme prosthetic group, regulates the key components of cell signaling, including BK(Ca) channels, guanylyl cyclase, NADPH oxidase, and the mitochondria respiratory chain. Cerebral vasodilator effects of CO are mediated via activation of BK(Ca) channels and guanylyl cyclase. CO, by inhibiting the major components of endogenous oxidant-generating machinery, NADPH oxidase and the cytochrome C oxidase of the mitochondrial respiratory chain, blocks formation of reactive oxygen species. Bilirubin, via redox cycling with biliverdin, is a potent oxidant scavenger that removes preformed oxidants. Overall, HO-2 has dual housekeeping cerebroprotective functions by maintaining autoregulation of cerebral blood flow aimed at improving neuronal survival in a changing environment, and by providing an effective defense mechanism that blocks oxidant formation and prevents cell death caused by oxidative stress.
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Affiliation(s)
- Helena Parfenova
- Laboratory for Research in Neonatal Physiology, Department of Physiology, University of Tennessee Health Science Center, Memphis, TN, USA.
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Zimmermann A, Leffler CW, Tcheranova D, Fedinec AL, Parfenova H. Cerebroprotective effects of the CO-releasing molecule CORM-A1 against seizure-induced neonatal vascular injury. Am J Physiol Heart Circ Physiol 2007; 293:H2501-7. [PMID: 17630349 DOI: 10.1152/ajpheart.00354.2007] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Endogenous CO, a product of heme oxygenase activity, has vasodilator and cytoprotective effects in the cerebral circulation of newborn pigs. CO-releasing molecule (CORM)-A1 (sodium boranocarbonate) is a novel, water-soluble, CO-releasing compound. We addressed the hypotheses that CORM-A1 1) can deliver CO to the brain and exert effects of CO on the cerebral microvasculature and 2) is cerebroprotective. Acute and delayed effects of topically and systemically administered CORM-A1 on cerebrovascular and systemic circulatory parameters were determined in anesthetized newborn pigs with implanted closed cranial windows. Topical application of CORM-A1 (10(-7)-10(-5) M) to the brain produced concentration-dependent CO release and pial arteriolar dilation. Systemically administered CORM-A1 (2 mg/kg ip or iv) caused pial arteriolar dilation and increased cortical cerebrospinal fluid CO concentration. Systemic CORM-A1 did not have acute or delayed effects on blood pressure, heart rate, or blood gases. Potential cerebroprotective vascular effects of CORM-A1 (2 mg/kg ip, 30 min before seizures) were tested 2 days after bicuculline-induced epileptic seizures (late postictal period). In control piglets, seizures reduced postictal cerebrovascular responsiveness to selective physiologically relevant vasodilators (bradykinin, hemin, and isoproterenol) indicative of cerebrovascular injury. In contrast, in CORM-A1-pretreated animals, no loss of postictal cerebrovascular reactivity was observed. We conclude that systemically administered CORM-A1 delivers CO to the brain, elicits the vasodilator and cytoprotective effects of CO in the cerebral circulation, and protects the neonatal brain from cerebrovascular injury caused by epileptic seizures.
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Affiliation(s)
- Aliz Zimmermann
- Laboratory for Research in Neonatal Physiology, Department of Physiology, Vascular Biology Center, University of Tennessee Health Science Center, Memphis, Tennessee 38163, USA
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Basuroy S, Leffler CW, Parfenova H. Signal‐specific contributions of NADPH oxidase and mitochondria to oxidative‐stress induced cerebral vascular endothelial injury. FASEB J 2007. [DOI: 10.1096/fasebj.21.6.a1383-b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Shyamali Basuroy
- PhysiologyUniversity of Tennessee Health Science Center894 Union Avenue, Memphis, TN, 38163MemphisTN38163
| | - Charles W. Leffler
- PhysiologyUniversity of Tennessee Health Science Center894 Union Avenue, Memphis, TN, 38163MemphisTN38163
| | - Helena Parfenova
- PhysiologyUniversity of Tennessee Health Science Center894 Union Avenue, Memphis, TN, 38163MemphisTN38163
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Basuroy S, Bhattacharya S, Tcheranova D, Qu Y, Regan RF, Leffler CW, Parfenova H. HO-2 provides endogenous protection against oxidative stress and apoptosis caused by TNF-α in cerebral vascular endothelial cells. Am J Physiol Cell Physiol 2006; 291:C897-908. [PMID: 16822952 DOI: 10.1152/ajpcell.00032.2006] [Citation(s) in RCA: 87] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Tumor necrosis factor-α (TNF-α) causes oxidative stress and apoptosis in a variety of cell types. Heme oxygenase (HO) degrades heme to bilirubin, an antioxidant, and carbon monoxide (CO), a cell cycle modulator, and a vasodilator. Newborn pig cerebral microvascular endothelial cells (CMVEC) highly express constitutive HO-2. We investigated the role of HO-2 in protection against TNF-α-induced apoptosis in cerebral vascular endothelium. In CMVEC from mice and newborn pigs, 15 ng/ml TNF-α alone, or with 10 μg/ml cycloheximide (CHX) caused apoptosis detected by nuclear translocation of p65 NF-κB, caspase-3 activation, DNA fragmentation, cell-cell contact destabilization, and cell detachment. TNF-α did not induce HO-1 expression in CMVEC. CMVEC from HO-2 knockout mice showed greater sensitivity to apoptosis caused by serum deprivation and TNF-α than did wild-type mice. TNF-α increased reactive oxygen species generation, including hydrogen peroxide and superoxide radicals, as detected by dihydrorhodamine-123 and dihydroethidium. The TNF-α response was inhibited by superoxide dismutase and catalase suggesting apoptosis is oxidative stress related. Inhibition of endogenous HO-2 in newborn pig CMVEC increased oxidative stress and exaggerated apoptosis caused by serum deprivation and TNF-α. In HO-1-overexpressing CMVEC (HO-1 selective induction by cobalt portophyrin), TNF-α did not cause apoptosis. A CO-releasing compound, CORM-A1, and bilirubin blocked TNF-α-induced reactive oxygen species accumulation and apoptosis consistent with the antioxidant and antiapoptotic roles of the end products of HO activity. We conclude that HO-2 is critical for protection of cerebrovascular endothelium against apoptotic changes induced by oxidative stress and cytokine-mediated inflammation.
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Affiliation(s)
- Shyamali Basuroy
- Dept. of Physiology, University of Tennessee Health Science Center, Memphis, TN 38163, USA.
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Leffler CW, Parfenova H, Fedinec AL, Basuroy S, Tcheranova D. Contributions of astrocytes and CO to pial arteriolar dilation to glutamate in newborn pigs. Am J Physiol Heart Circ Physiol 2006; 291:H2897-904. [PMID: 16891404 PMCID: PMC1676252 DOI: 10.1152/ajpheart.00722.2006] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Astrocytes can act as intermediaries between neurons and cerebral arterioles to regulate vascular tone in response to neuronal activity. Release of glutamate from presynaptic neurons increases blood flow to match metabolic demands. CO is a gasotransmitter that can be related to neural function and blood flow regulation in the brain. The present study addresses the hypothesis that glutamatergic stimulation promotes perivascular astrocyte CO production and pial arteriolar dilation in the newborn brain. Experiments used anesthetized newborn pigs with closed cranial windows, piglet astrocytes, and cerebrovascular endothelial cells in primary culture and immunocytochemical visualization of astrocytic markers. Pial arterioles and arteries of newborn pigs are ensheathed by astrocytes visualized by glial fibrillary acidic protein staining. Treatment (2 h) of astrocytes in culture with L-2-alpha-aminoadipic acid (L-AAA), followed by 14 h in toxin free medium, dose-dependently increased cell detachment, suggesting injury. Conversely, 16 h of continuous exposure to L-AAA caused no decrease in endothelial cell attachment. In vivo, topical L-AAA (2 mM, 5 h) disrupted the cortical glia limitans histologically. Such treatment also eliminated pial arteriolar dilation to the astrocyte-dependent dilator ADP and to glutamate but not to isoproterenol or CO. Glutamate stimulated CO production by the brain surface that also was abolished following L-AAA. In contrast, tetrodotoxin blocked dilation to N-methyl-D-aspartate but not to glutamate, isoproterenol, or CO or the glutamate-induced increase in CO. The concurrent loss of CO production and pial arteriolar dilation to glutamate following astrocyte injury suggests astrocytes may employ CO as a gasotransmitter for glutamatergic cerebrovascular dilation.
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Affiliation(s)
- Charles W Leffler
- Dept. of Physiology, University of Tennessee, Memphis, TN 38163, USA.
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Parfenova H, Basuroy S, Bhattacharya S, Tcheranova D, Qu Y, Regan RF, Leffler CW. Glutamate induces oxidative stress and apoptosis in cerebral vascular endothelial cells: contributions of HO-1 and HO-2 to cytoprotection. Am J Physiol Cell Physiol 2006; 290:C1399-410. [PMID: 16371440 DOI: 10.1152/ajpcell.00386.2005] [Citation(s) in RCA: 139] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In cerebral circulation, epileptic seizures associated with excessive release of the excitatory neurotransmitter glutamate cause endothelial injury. Heme oxygenase (HO), which metabolizes heme to a vasodilator, carbon monoxide (CO), and antioxidants, biliverdin/bilirubin, is highly expressed in cerebral microvessels as a constitutive isoform, HO-2, whereas the inducible form, HO-1, is not detectable. Using cerebral vascular endothelial cells from newborn pigs and HO-2-knockout mice, we addressed the hypotheses that 1) glutamate induces oxidative stress-related endothelial death by apoptosis, and 2) HO-1 and HO-2 are protective against glutamate cytotoxicity. In cerebral endothelial cells, glutamate (0.1–2.0 mM) increased formation of reactive oxygen species, including superoxide radicals, and induced major keystone events of apoptosis, such as NF-κB nuclear translocation, caspase-3 activation, DNA fragmentation, and cell detachment. Glutamate-induced apoptosis was greatly exacerbated in HO-2 gene-deleted murine cerebrovascular endothelial cells and in porcine cells with pharmacologically inhibited HO-2 activity. Glutamate toxicity was prevented by superoxide dismutase, suggesting apoptotic changes are oxidative stress related. When HO-1 was pharmacologically upregulated by cobalt protoporphyrin, apoptotic effects of glutamate in cerebral endothelial cells were completely prevented. Glutamate-induced reactive oxygen species production and apoptosis were blocked by a CO-releasing compound, CORM-A1 (50 μM), and by bilirubin (1 μM), consistent with the antioxidant and cytoprotective roles of the end products of HO activity. We conclude that both HO-1 and HO-2 have anti-apoptotic effects against oxidative stress-related glutamate toxicity in cerebral vascular endothelium. Although HO-1, when induced, provides powerful protection, HO-2 is an essential endogenous anti-apoptotic factor against glutamate toxicity in the cerebral vascular endothelium.
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Affiliation(s)
- Helena Parfenova
- Department of Physiology, University of Tennessee Health Science Center, 894 Union Ave., Memphis, TN 38163, USA.
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Basuroy S, Bhattacharya S, Qu Y, Regan RF, Leffler CW, Parfenova H. HO‐2 gene deletion increases NFkB activation and sensitizes cerebral microvascular endothelial cells to TNF‐alpha‐induced apoptosis. FASEB J 2006. [DOI: 10.1096/fasebj.20.4.a292-c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
| | | | - Yan Qu
- Emergency medicineThomas Jefferson University1020 Sansom StreetPhiladelphiaPennsylvania19107
| | - Raymond F Regan
- Emergency medicineThomas Jefferson University1020 Sansom StreetPhiladelphiaPennsylvania19107
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Parfenova H, Basuroy S, Tcheranova D, Bhattacharya S, Zimmermann A, Leffler CW. Carbon monoxide (CO) protects against apoptosis caused by seizure‐related excitotoxic and inflammatory factors in the cerebral vasculature. FASEB J 2006. [DOI: 10.1096/fasebj.20.4.a292-d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
| | | | | | | | - Aliz Zimmermann
- PhysiologyUniversity of Tennessee894 Union AvenueMemphisTN38163
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Affiliation(s)
- Dilyara Tcheranova
- Department of PhysiologyUniversity of Tennessee Health Science Center894 Union aveMemphisTN38163
| | - Shyamali Basuroy
- Department of PhysiologyUniversity of Tennessee Health Science Center894 Union aveMemphisTN38163
| | - Helena Parfenova
- Department of PhysiologyUniversity of Tennessee Health Science Center894 Union aveMemphisTN38163
| | - Charles W. Leffler
- Department of PhysiologyUniversity of Tennessee Health Science Center894 Union aveMemphisTN38163
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46
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Zimmermann A, Leffler CW, Parfenova H. Increase in circulating endothelial cells correlates with vascular dysfunction caused by epileptic seizures. FASEB J 2006. [DOI: 10.1096/fasebj.20.4.a732-b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Aliz Zimmermann
- Department of PhysiologyUniversity of Tennessee Health Science Center894 Union AvenueMemphisTN38163
| | - Charles W. Leffler
- Department of PhysiologyUniversity of Tennessee Health Science Center894 Union AvenueMemphisTN38163
| | - Helena Parfenova
- Department of PhysiologyUniversity of Tennessee Health Science Center894 Union AvenueMemphisTN38163
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Abstract
This review focuses on two gaseous cellular messenger molecules, CO and H2S, that are involved in cerebrovascular flow regulation. CO is a dilatory mediator in active hyperemia, autoregulation, hypoxic dilation, and counteracting vasoconstriction. It is produced from heme by a constitutively expressed enzyme [heme oxygenase (HO)-2] expressed highly in the brain and by an inducible enzyme (HO-1). CO production is regulated by controlling substrate availability, HO-2 catalytic activity, and HO-1 expression. CO dilates arterioles by binding to heme that is bound to large-conductance Ca2+-activated K+ channels. This binding elevates channel Ca2+ sensitivity, that increases coupling of Ca2+ sparks to large-conductance Ca2+-activated K+ channel openings and, thereby, hyperpolarizes the vascular smooth muscle. In addition to dilating blood vessels, CO can either inhibit or accentuate vascular cell proliferation and apoptosis, depending on conditions. H2S may also function as a cerebrovascular dilator. It is produced in vascular smooth muscle cells by hydrolysis of l-cysteine catalyzed by cystathione gamma-lyase (CSE). H2S dilates arterioles at physiologically relevant concentrations via activation of ATP-sensitive K+ channels. In addition to dilating blood vessels, H2S promotes apoptosis of vascular smooth muscle cells and inhibits proliferation-associated vascular remodeling. Thus both CO and H2S modulate the function and the structure of circulatory system. Both the HO-CO and CSE-H2S systems have potential to interact with NO and prostanoids in the cerebral circulation. Much of the physiology and biochemistry of HO-CO and CSE-H2S in the cerebral circulation remains open for exploration.
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Affiliation(s)
- Charles W Leffler
- Dept. of Physiology, University of Tennessee Health Science Center, 894 Union Ave., Memphis, TN 38163, USA.
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48
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Pourcyrous M, Parfenova H, Leffler CW. The effects of orally administered Sildenafil (Viagra) on cerebral circulation in newborn pigs. FASEB J 2006. [DOI: 10.1096/fasebj.20.4.a295-b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Massroor Pourcyrous
- PediatricsUniversity of Tennessee Health Science centerNewborn Center853 Jefferson Ave. Room 201MemphisTennessee38163
| | - Helena Parfenova
- PhysiologyUniversity of Tennessee Health Science Center894 Union Ave.MemphisTennessee38163
| | - Charles W Leffler
- PhysiologyUniversity of Tennessee Health Science Center894 Union Ave.MemphisTennessee38163
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Abstract
Carbon monoxide (CO) and nitric oxide (NO) can be involved in the regulation of cerebral circulation. Inhibition of production of either one of these gaseous intercellular messengers inhibits newborn pig cerebral arteriolar dilation to the excitatory amino acid glutamate. Glutamate can increase NO production. Therefore, the present study tests the hypothesis that NO, which is increased by glutamate, stimulates the production of CO by cerebral microvessels. Experiments used freshly isolated cerebral microvessels from piglets that express only heme oxygenase-2 (HO-2). CO production was measured by gas chromatography-mass spectrometry. Although inhibition of nitric oxide synthase (NOS) with N(omega)-nitro-l-arginine (l-NNA) did not alter basal HO-2 catalytic activity or CO production, l-NNA blocked glutamate stimulation of HO-2 activity and CO production. Furthermore, the NO donor sodium nitroprusside mimicked the actions of glutamate on HO-2 and CO production. The action of NO appears to be via cGMP because 8-bromo-cGMP mimics and 1H-[1,2,4]oxadiazole-[4,3-a]quinoxalin-1-one (ODQ) blocks glutamate stimulation of CO production and HO-2 catalytic activity. Inhibitors of neither casein kinase nor phosphotidylinositol 3-kinase altered HO-2 catalytic activity. Conversely, inhibition of calmodulin with calmidazolium chloride blocked glutamate stimulation of CO production and reduced HO-2 catalytic activity. These data suggest that glutamate may activate NOS producing NO that leads to CO synthesis via a cGMP-dependent elevation of HO-2 catalytic activity. These results are consistent with the findings in vivo that either HO or NOS inhibition blocks cerebrovascular dilation to glutamate in piglets.
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Affiliation(s)
- Charles W Leffler
- Department of Physiology, University of Tennessee Health Science Center, 894 Union Ave., Memphis, TN 38163, USA.
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50
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Abstract
Carbon monoxide (CO) is an endogenous paracrine and autocrine gaseous messenger that regulates physiological functions in a wide variety of tissues. CO induces vasodilation by activating arterial smooth muscle large-conductance Ca2+-activated potassium (BK(Ca)) channels. However, the mechanism by which CO activates BK(Ca) channels remains unclear. Here, we tested the hypothesis that CO activates BK(Ca) channels by binding to channel-bound heme, a BK(Ca) channel inhibitor, and altering the interaction between heme and the conserved heme-binding domain (HBD) of the channel alpha subunit C terminus. Data obtained using thin-layer chromatography, spectrophotometry, mass spectrometry (MS), and MS-MS indicate that CO modifies the binding of reduced heme to the alpha subunit HBD. In contrast, CO does not alter the interaction between the HBD and oxidized heme (hemin), to which CO cannot bind. Consistent with these findings, electrophysiological measurements of native and cloned (cbv) cerebral artery smooth muscle BK(Ca) channels show that CO reverses BK(Ca) channel inhibition by heme but not by hemin. Site-directed mutagenesis of the cbv HBD from CKACH to CKASR abolished both heme-induced channel inhibition and CO-induced activation. Furthermore, on binding CO, heme switches from being a channel inhibitor to an activator. These findings indicate that reduced heme is a functional CO receptor for BK(Ca) channels, introduce a unique mechanism by which CO regulates the activity of a target protein, and reveal a novel process by which a gaseous messenger regulates ion channel activity.
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Affiliation(s)
- Jonathan H Jaggar
- Department of Physiology, University of Tennessee Health Science Center, Memphis 38139, USA.
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