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Zhang D, Krause BM, Schmalz HG, Wohlfart P, Yard BA, Schubert R. ET-CORM Mediated Vasorelaxation of Small Mesenteric Arteries: Involvement of Kv7 Potassium Channels. Front Pharmacol 2021; 12:702392. [PMID: 34552483 PMCID: PMC8451721 DOI: 10.3389/fphar.2021.702392] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2021] [Accepted: 08/24/2021] [Indexed: 11/18/2022] Open
Abstract
Although the vasoactive properties of carbon monoxide (CO) have been extensively studied, the mechanism by which CO mediates vasodilation is not completely understood. Through-out published studies on CO mediated vasodilation there is inconsistency on the type of K+-channels that are activated by CO releasing molecules (CORMs). Since the vasorelaxation properties of enzyme triggered CORMs (ET-CORMs) have not been studied thus far, we first assessed if ET-CORMs can mediate vasodilation of small mesenteric arteries and subsequently addressed the role of soluble guanylate cyclase (sGC) and that of K-channels herein. To this end, 3 different types of ET-CORMs that either contain acetate (rac-1 and rac-4) or pivalate (rac-8) as ester functionality, were tested ex vivo on methoxamine pre-contracted small rat mesenteric arteries in a myograph setting. Pre-contracted mesenteric arteries strongly dilated upon treatment with both types of acetate containing ET-CORMs (rac-1 and rac-4), while treatment with the pivalate containing ET-CORM (rac-8) resulted in no vasodilation. Pre-treatment of mesenteric arteries with the sGC inhibitor ODQ abolished rac-4 mediated vasodilation, similar as for the known sGC activator SNP. Likewise, rac-4 mediated vasodilation did not occur in KCL pretreated mesenteric arteries. Although mesenteric arteries abundantly expressed a variety of K+-channels only Kv7 channels were found to be of functional relevance for rac-4 mediated vasodilation. In conclusion the current results identified Kv7 channels as the main channel by which rac-4 mediates vasodilation. In keeping with the central role of Kv7 in the control of vascular tone and peripheral resistance these promising ex-vivo data warrant further in vivo studies, particularly in models of primary hypertension or cardiac diseases, to assess the potential use of ET-CORMs in these diseases.
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Affiliation(s)
- Danfeng Zhang
- Department of Nephrology, Endocrinology and Rheumatology, Fifth Medical Department of Medicine, Medical Faculty Mannheim, University of Heidelberg, Mannheim, Germany.,Department of Nephrology, the Second Hospital of Anhui Medical University, Hefei, China
| | | | | | - Paulus Wohlfart
- Diabetes Research, Sanofi Aventis Deutschland GmbH, Frankfurt, Germany
| | - Benito A Yard
- Department of Nephrology, Endocrinology and Rheumatology, Fifth Medical Department of Medicine, Medical Faculty Mannheim, University of Heidelberg, Mannheim, Germany.,European Center of Angioscience (ECAS), Research Division Cardiovascular Physiology, Medical Faculty Mannheim, Heidelberg University, Frankfurt, Germany
| | - Rudolf Schubert
- European Center of Angioscience (ECAS), Research Division Cardiovascular Physiology, Medical Faculty Mannheim, Heidelberg University, Frankfurt, Germany.,Physiology, Institute of Theoretical Medicine, Medical Faculty, University of Augsburg, Augsburg, Germany
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Abstract
The cerebral microcirculation undergoes dynamic changes in parallel with the development of neurons, glia, and their energy metabolism throughout gestation and postnatally. Cerebral blood flow (CBF), oxygen consumption, and glucose consumption are as low as 20% of adult levels in humans born prematurely but eventually exceed adult levels at ages 3 to 11 years, which coincide with the period of continued brain growth, synapse formation, synapse pruning, and myelination. Neurovascular coupling to sensory activation is present but attenuated at birth. By 2 postnatal months, the increase in CBF often is disproportionately smaller than the increase in oxygen consumption, in contrast to the relative hyperemia seen in adults. Vascular smooth muscle myogenic tone increases in parallel with developmental increases in arterial pressure. CBF autoregulatory response to increased arterial pressure is intact at birth but has a more limited range with arterial hypotension. Hypoxia-induced vasodilation in preterm fetal sheep with low oxygen consumption does not sustain cerebral oxygen transport, but the response becomes better developed for sustaining oxygen transport by term. Nitric oxide tonically inhibits vasomotor tone, and glutamate receptor activation can evoke its release in lambs and piglets. In piglets, astrocyte-derived carbon monoxide plays a central role in vasodilation evoked by glutamate, ADP, and seizures, and prostanoids play a large role in endothelial-dependent and hypercapnic vasodilation. Overall, homeostatic mechanisms of CBF regulation in response to arterial pressure, neuronal activity, carbon dioxide, and oxygenation are present at birth but continue to develop postnatally as neurovascular signaling pathways are dynamically altered and integrated. © 2021 American Physiological Society. Compr Physiol 11:1-62, 2021.
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Dongó E, Kiss L. The Potential Role of Hydrogen Sulfide in the Regulation of Cerebrovascular Tone. Biomolecules 2020; 10:biom10121685. [PMID: 33339440 PMCID: PMC7766080 DOI: 10.3390/biom10121685] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2020] [Revised: 12/09/2020] [Accepted: 12/14/2020] [Indexed: 01/15/2023] Open
Abstract
A better understanding of the regulation of cerebrovascular circulation is of great importance because stroke and other cerebrovascular diseases represent a major concern in healthcare leading to millions of deaths yearly. The circulation of the central nervous system is regulated in a highly complex manner involving many local factors and hydrogen sulfide (H2S) is emerging as one such possible factor. Several lines of evidence support that H2S takes part in the regulation of vascular tone. Examinations using either exogenous treatment with H2S donor molecules or alterations to the enzymes that are endogenously producing this molecule revealed numerous important findings about its physiological and pathophysiological role. The great majority of these studies were performed on vessel segments derived from the systemic circulation but there are important observations made using cerebral vessels as well. The findings of these experimental works indicate that H2S is having a complex, pleiotropic effect on the vascular wall not only in the systemic circulation but in the cerebrovascular region as well. In this review, we summarize the most important experimental findings related to the potential role of H2S in the cerebral circulation.
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Affiliation(s)
- Eleni Dongó
- Department of Physiology, Semmelweis University, 1088 Budapest, Hungary
- Department of Neurology, Semmelweis University, 1088 Budapest, Hungary;
| | - Levente Kiss
- Department of Physiology, Semmelweis University, 1088 Budapest, Hungary
- Correspondence: ; Tel.: +36-20-384-5753
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Estrogen Receptors and Estrogen-Induced Uterine Vasodilation in Pregnancy. Int J Mol Sci 2020; 21:ijms21124349. [PMID: 32570961 PMCID: PMC7352873 DOI: 10.3390/ijms21124349] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2020] [Revised: 06/10/2020] [Accepted: 06/15/2020] [Indexed: 12/16/2022] Open
Abstract
Normal pregnancy is associated with dramatic increases in uterine blood flow to facilitate the bidirectional maternal–fetal exchanges of respiratory gases and to provide sole nutrient support for fetal growth and survival. The mechanism(s) underlying pregnancy-associated uterine vasodilation remain incompletely understood, but this is associated with elevated estrogens, which stimulate specific estrogen receptor (ER)-dependent vasodilator production in the uterine artery (UA). The classical ERs (ERα and ERβ) and the plasma-bound G protein-coupled ER (GPR30/GPER) are expressed in UA endothelial cells and smooth muscle cells, mediating the vasodilatory effects of estrogens through genomic and/or nongenomic pathways that are likely epigenetically modified. The activation of these three ERs by estrogens enhances the endothelial production of nitric oxide (NO), which has been shown to play a key role in uterine vasodilation during pregnancy. However, the local blockade of NO biosynthesis only partially attenuates estrogen-induced and pregnancy-associated uterine vasodilation, suggesting that mechanisms other than NO exist to mediate uterine vasodilation. In this review, we summarize the literature on the role of NO in ER-mediated mechanisms controlling estrogen-induced and pregnancy-associated uterine vasodilation and our recent work on a “new” UA vasodilator hydrogen sulfide (H2S) that has dramatically changed our view of how estrogens regulate uterine vasodilation in pregnancy.
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Liu T, Mukosera GT, Blood AB. The role of gasotransmitters in neonatal physiology. Nitric Oxide 2019; 95:29-44. [PMID: 31870965 DOI: 10.1016/j.niox.2019.12.002] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2019] [Revised: 11/07/2019] [Accepted: 12/17/2019] [Indexed: 12/12/2022]
Abstract
The gasotransmitters, nitric oxide (NO), hydrogen sulfide (H2S), and carbon monoxide (CO), are endogenously-produced volatile molecules that perform signaling functions throughout the body. In biological tissues, these small, lipid-permeable molecules exist in free gaseous form for only seconds or less, and thus they are ideal for paracrine signaling that can be controlled rapidly by changes in their rates of production or consumption. In addition, tissue concentrations of the gasotransmitters are influenced by fluctuations in the level of O2 and reactive oxygen species (ROS). The normal transition from fetus to newborn involves a several-fold increase in tissue O2 tensions and ROS, and requires rapid morphological and functional adaptations to the extrauterine environment. This review summarizes the role of gasotransmitters as it pertains to newborn physiology. Particular focus is given to the vasculature, ventilatory, and gastrointestinal systems, each of which uniquely illustrate the function of gasotransmitters in the birth transition and newborn periods. Moreover, given the relative lack of studies on the role that gasotransmitters play in the newborn, particularly that of H2S and CO, important gaps in knowledge are highlighted throughout the review.
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Affiliation(s)
- Taiming Liu
- Department of Pediatrics, Division of Neonatology, Loma Linda University School of Medicine, Loma Linda, CA, 92354, USA
| | - George T Mukosera
- Department of Pediatrics, Division of Neonatology, Loma Linda University School of Medicine, Loma Linda, CA, 92354, USA
| | - Arlin B Blood
- Department of Pediatrics, Division of Neonatology, Loma Linda University School of Medicine, Loma Linda, CA, 92354, USA; Lawrence D. Longo Center for Perinatal Biology, Loma Linda University School of Medicine, Loma Linda, CA, 92354, USA.
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Ahmed RF, Moussa RA, Eldemerdash RS, Zakaria MM, Abdel-Gaber SA. Ameliorative effects of silymarin on HCl-induced acute lung injury in rats; role of the Nrf-2/HO-1 pathway. IRANIAN JOURNAL OF BASIC MEDICAL SCIENCES 2019; 22:1483-1492. [PMID: 32133068 PMCID: PMC7043873 DOI: 10.22038/ijbms.2019.14069] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/29/2019] [Accepted: 07/03/2019] [Indexed: 12/25/2022]
Abstract
OBJECTIVES Aspiration is a common cause of acute lung injury (ALI), which lacks an effective treatment. Inflammation and oxidative stress play key roles in ALI development. Silymarin is an active extract of Silybum marianum plant seeds (milk thistle). Silymarin has potent anti-inflammatory and antioxidant effects; however its role in aspiration induced ALI has not been investigated. The aim of this study is to investigate the role of silymarin in the treatment of hydrochloric acid (HCl) aspiration induced ALI and explores its mechanisms of action. MATERIALS AND METHODS The study included three groups of rats: Control non-treated group, ALI group (intra-tracheal HCl injected), and silymarin treated ALI group. White blood cells (WBCs) with differential count, oxidative stress parameters, B-cell lymphoma 2 (Bcl-2), transforming growth factor-beta (TGF-β), cyclooxygenase 2 (COX-2), nuclear factor erythroid 2-related factor-2 (Nrf-2), and heme oxygenase-1 (HO-1) were investigated. Lung tissue histopathology and immunohistochemical expression of survivin and proliferating cell nuclear antigen (PCNA) were also examined. RESULTS The results of the study showed that HCL caused histopathological changes in ALI with leukocytopenia and increased oxidative stress biomarkers. It increased TGF-β, up-regulated mRNA expression of COX-2, Nrf-2, and HO-1 and increased survivin and PCNA but decreased Bcl-2. Silymarin ameliorated the histopathological lung injury with further up-regulation of Nrf-2 and HO-1 mRNA and decreased the inflammatory and fibrotic parameters together with up-regulation of the anti-apoptotic and the proliferation parameters. CONCLUSION The protective effect of silymarin against ALI is mediated by Nrf-2/HO-1 pathway with subsequent antioxidant, anti-inflammatory, antiapoptotic, and proliferating activities.
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Affiliation(s)
- Rasha F Ahmed
- Department of Medical Biochemistry, Faculty of Medicine, Minia University, 61511 Minia, Egypt
| | - Rabab A Moussa
- Department of Pathology, Faculty of Medicine, Minia University, 61511 Minia, Egypt
| | - Reda S Eldemerdash
- Research Building, Urology & Nephrology Center, Mansoura University, 35516 Mansoura, Egypt
| | - Mahmoud M Zakaria
- Research Building, Urology & Nephrology Center, Mansoura University, 35516 Mansoura, Egypt
| | - Seham A Abdel-Gaber
- Department of Pharmacology, Faculty of Medicine, Minia University, 61511 Minia, Egypt
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Pires PW, Earley S. Neuroprotective effects of TRPA1 channels in the cerebral endothelium following ischemic stroke. eLife 2018; 7:35316. [PMID: 30239332 PMCID: PMC6177258 DOI: 10.7554/elife.35316] [Citation(s) in RCA: 63] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2018] [Accepted: 09/18/2018] [Indexed: 02/07/2023] Open
Abstract
Hypoxia and ischemia are linked to oxidative stress, which can activate the oxidant-sensitive transient receptor potential ankyrin 1 (TRPA1) channel in cerebral artery endothelial cells, leading to vasodilation. We hypothesized that TRPA1 channels in endothelial cells are activated by hypoxia-derived reactive oxygen species, leading to cerebral artery dilation and reduced ischemic damage. Using isolated cerebral arteries expressing a Ca2+ biosensor in endothelial cells, we show that 4-hydroxynonenal and hypoxia increased TRPA1 activity, detected as TRPA1 sparklets. TRPA1 activity during hypoxia was blocked by antioxidants and by TRPA1 antagonism. Hypoxia caused dilation of cerebral arteries, which was disrupted by antioxidants, TRPA1 blockade and by endothelial cell-specific Trpa1 deletion (Trpa1 ecKO mice). Loss of TRPA1 channels in endothelial cells increased cerebral infarcts, whereas TRPA1 activation with cinnamaldehyde reduced infarct in wildtype, but not Trpa1 ecKO, mice. These data suggest that endothelial TRPA1 channels are sensors of hypoxia leading to vasodilation, thereby reducing ischemic damage.
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Affiliation(s)
- Paulo Wagner Pires
- Department of Pharmacology, Center for Cardiovascular Research, University of Nevada, Reno, United States
| | - Scott Earley
- Department of Pharmacology, Center for Cardiovascular Research, University of Nevada, Reno, United States
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Ghanizada H, Arngrim N, Schytz HW, Olesen J, Ashina M. Carbon monoxide inhalation induces headache but no migraine in patients with migraine without aura. Cephalalgia 2018. [PMID: 29540069 DOI: 10.1177/0333102418765771] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
INTRODUCTION Carbon monoxide is an endogenously produced signaling gasotransmitter known to cause headache and vasodilation. We hypothesized that inhalation of carbon monoxide would induce migraine-like attacks in migraine without aura patients. METHODS In a randomized, double-blind, placebo-controlled crossover design, 12 migraine patients were allocated to inhalation of carbon monoxide (carboxyhemoglobin 22%) or placebo on two separate days. Headache and migraine characteristics were recorded during hospital (0-2 hours) and post-hospital (2-13 hours) phases. RESULTS Six patients (50%) developed migraine-like attacks after carbon monoxide compared to two after placebo (16.7%) ( p = 0.289). The median time to onset of migraine-like attacks after carbon monoxide inhalation was 7.5 h (range 3-12) compared to 11.5 h (range 11-12) after placebo. Nine out of 12 patients (75%) developed prolonged headache after carbon monoxide. The area under the curve for headache score (0-13 hours) was increased after carbon monoxide compared with placebo ( p = 0.033). CONCLUSION Carbon monoxide inhalation did not provoke more migraine-like attacks in migraine patients compared to placebo, but induced more headache in patients compared to placebo. These data suggest that non-toxic concentrations of carbon monoxide had low potency in migraine induction and that the carbon monoxide inhalation model is not suitable to study migraine.
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Affiliation(s)
- Hashmat Ghanizada
- Danish Headache Center and Department of Neurology, Rigshospitalet Glostrup, Faculty of Health and Medical Sciences, University of Copenhagen, Denmark
| | - Nanna Arngrim
- Danish Headache Center and Department of Neurology, Rigshospitalet Glostrup, Faculty of Health and Medical Sciences, University of Copenhagen, Denmark
| | - Henrik Winther Schytz
- Danish Headache Center and Department of Neurology, Rigshospitalet Glostrup, Faculty of Health and Medical Sciences, University of Copenhagen, Denmark
| | - Jes Olesen
- Danish Headache Center and Department of Neurology, Rigshospitalet Glostrup, Faculty of Health and Medical Sciences, University of Copenhagen, Denmark
| | - Messoud Ashina
- Danish Headache Center and Department of Neurology, Rigshospitalet Glostrup, Faculty of Health and Medical Sciences, University of Copenhagen, Denmark
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Arngrim N, Schytz HW, Britze J, Vestergaard MB, Sander M, Olsen KS, Olesen J, Ashina M. Carbon monoxide inhalation induces headache in a human headache model. Cephalalgia 2017; 38:697-706. [DOI: 10.1177/0333102417708768] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Introduction Carbon monoxide (CO) is an endogenously produced signalling molecule that has a role in nociceptive processing and cerebral vasodilatation. We hypothesized that inhalation of CO would induce headache and vasodilation of cephalic and extracephalic arteries. Methods In a randomized, double-blind, placebo-controlled crossover design, 12 healthy volunteers were allocated to inhalation of CO (carboxyhemoglobin 22%) or placebo on two separate days. Headache was scored on a verbal rating scale from 0–10. We recorded mean blood velocity in the middle cerebral artery (VMCA) by transcranial Doppler, diameter of the superficial temporal artery (STA) and radial artery (RA) by high-resolution ultrasonography and facial skin blood flow by laser speckle contrast imaging. Results Ten volunteers developed headache after CO compared to six after placebo. The area under the curve for headache (0–12 hours) was increased after CO compared with placebo ( p = 0.021). CO increased VMCA ( p = 0.002) and facial skin blood flow ( p = 0.012), but did not change the diameter of the STA ( p = 0.060) and RA ( p = 0.433). Conclusion In conclusion, the study demonstrated that CO caused mild prolonged headache but no arterial dilatation in healthy volunteers. We suggest this may be caused by a combination of hypoxic and direct cellular effects of CO.
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Affiliation(s)
- Nanna Arngrim
- Danish Headache Center and Department of Neurology, Rigshospitalet Glostrup, Faculty of Health and Medical Sciences, University of Copenhagen, Glostrup, Denmark
| | - Henrik Winther Schytz
- Danish Headache Center and Department of Neurology, Rigshospitalet Glostrup, Faculty of Health and Medical Sciences, University of Copenhagen, Glostrup, Denmark
| | - Josefine Britze
- Danish Headache Center and Department of Neurology, Rigshospitalet Glostrup, Faculty of Health and Medical Sciences, University of Copenhagen, Glostrup, Denmark
| | - Mark Bitsch Vestergaard
- Functional Imaging Unit, Department of Clinical Physiology, Nuclear Medicine and PET, Rigshospitalet Glostrup, Faculty of Health and Medical Sciences, University of Copenhagen, Glostrup, Denmark
| | - Mikael Sander
- Department of Cardiology, Bispebjerg and Frederiksberg Hospital, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Karsten Skovgaard Olsen
- Department of Neuroanaesthesiology, The Neuroscience Centre, Rigshospitalet Glostrup, Faculty of Health and Medical Sciences, University of Copenhagen, Glostrup, Denmark
| | - Jes Olesen
- Danish Headache Center and Department of Neurology, Rigshospitalet Glostrup, Faculty of Health and Medical Sciences, University of Copenhagen, Glostrup, Denmark
| | - Messoud Ashina
- Danish Headache Center and Department of Neurology, Rigshospitalet Glostrup, Faculty of Health and Medical Sciences, University of Copenhagen, Glostrup, Denmark
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Abraham NG, Junge JM, Drummond GS. Translational Significance of Heme Oxygenase in Obesity and Metabolic Syndrome. Trends Pharmacol Sci 2015; 37:17-36. [PMID: 26515032 DOI: 10.1016/j.tips.2015.09.003] [Citation(s) in RCA: 106] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2015] [Revised: 09/10/2015] [Accepted: 09/17/2015] [Indexed: 01/04/2023]
Abstract
The global epidemic of obesity continues unabated with sequelae of diabetes and metabolic syndrome. This review reflects the dramatic increase in research on the role of increased expression of heme oxygenase (HO)-1/HO-2, biliverdin reductase, and HO activity on vascular disease. The HO system engages with other systems to mitigate the deleterious effects of oxidative stress in obesity and cardiovascular disease (CVD). Recent reports indicate that HO-1/HO-2 protein expression and HO activity have several important roles in hemostasis and reactive oxygen species (ROS)-dependent perturbations associated with metabolic syndrome. HO-1 protects tissue during inflammatory stress in obesity through the degradation of pro-oxidant heme and the production of carbon monoxide (CO) and bilirubin, both of which have anti-inflammatory and anti-apoptotic properties. By contrast, repression of HO-1 is associated with increases of cellular heme and inflammatory conditions including hypertension, stroke, and atherosclerosis. HO-1 is a major focus in the development of potential therapeutic strategies to reverse the clinical complications of obesity and metabolic syndrome.
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Affiliation(s)
- Nader G Abraham
- Departments of Medicine and Pharmacology, New York Medical College, School of Medicine, Valhalla, NY 10595, USA; Marshall University, Joan C. Edwards School of Medicine, Huntington, WV 25701, USA.
| | - Joshua M Junge
- Departments of Medicine and Pharmacology, New York Medical College, School of Medicine, Valhalla, NY 10595, USA
| | - George S Drummond
- Departments of Medicine and Pharmacology, New York Medical College, School of Medicine, Valhalla, NY 10595, USA
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Fredenburgh LE, Merz AA, Cheng S. Haeme oxygenase signalling pathway: implications for cardiovascular disease. Eur Heart J 2015; 36:1512-8. [PMID: 25827602 PMCID: PMC4475572 DOI: 10.1093/eurheartj/ehv114] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/08/2015] [Revised: 02/25/2015] [Accepted: 03/19/2015] [Indexed: 01/04/2023] Open
Abstract
Evidence now points to the haeme oxygenase (HO) pathway as a possible actor in modulating risk for cardiovascular disease (CVD). In particular, the HO pathway may represent a key endogenous modulator of oxidative, inflammatory, and cytotoxic stress while also exhibiting vasoregulatory properties. In this review, we summarize the accumulating experimental and emerging clinical data indicating how activity of the HO pathway and its products may play a role in mechanisms underlying the development of CVD. We also identify gaps in the literature to date and suggest future directions for investigation. Because HO pathway activity can be influenced not only by genetic traits and environmental stimuli but also by a variety of existing pharmacologic interventions, the pathway could serve as a prime target for reducing the overall burden of CVD. Further work is needed to determine the role of HO pathway products as possible prognostic markers of risk for clinical CVD events and the extent to which therapeutic augmentation or inhibition of HO pathway activity could serve to modify CVD risk.
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Affiliation(s)
- Laura E Fredenburgh
- Division of Pulmonary and Critical Care Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA
| | - Allison A Merz
- Division of Cardiovascular Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA
| | - Susan Cheng
- Division of Cardiovascular Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA Framingham Heart Study, Framingham, MA, USA
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Association of HMOX1 and NQO1 Polymorphisms with Metabolic Syndrome Components. PLoS One 2015; 10:e0123313. [PMID: 25933176 PMCID: PMC4416764 DOI: 10.1371/journal.pone.0123313] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2015] [Accepted: 02/06/2015] [Indexed: 12/23/2022] Open
Abstract
Metabolic syndrome (MetS) is among the most important public health problems worldwide, and is recognized as a major risk factor for various illnesses, including type 2 diabetes mellitus, obesity, and cardiovascular diseases. Recently, oxidative stress has been suggested as part of MetS aetiology. The heme oxygenase 1 (HMOX1) and NADH:quinone oxidoreductase 1 (NQO1) genes are crucial mediators of cellular defence against oxidative stress. In the present study, we analysed the associations of HMOX1 (GT)n and NQO1 C609T polymorphisms with MetS and its components. Our study population comprised 735 Mexican Mestizos unrelated volunteers recruited from different tertiary health institutions from Mexico City. In order to know the HMOX1 (GT)n and NQO1 C609T allele frequencies in Amerindians, we included a population of 241 Amerindian native speakers. Their clinical and demographic data were recorded. The HMOX1 (GT)n polymorphism was genotyped using PCR and fluorescence technology. NQO1 C609T polymorphism genotyping was performed using TaqMan probes. Short allele (<25 GT repeats) of the HMOX1 polymorphism was associated with high systolic and diastolic blood pressure, and the T allele of the NQO1 C609T polymorphism was associated with increased triglyceride levels and decreased HDL-c levels, but only in individuals with MetS. This is the first study to analyse the association between MetS and genes involved in oxidative stress among Mexican Mestizos. Our data suggest that polymorphisms of HMOX1 and NQO1 genes are associated with a high risk of metabolic disorders, including high systolic and diastolic blood pressure, hypertriglyceridemia, and low HDL-c levels in Mexican Mestizo individuals.
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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] [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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El-Bassossy HM, Hassan N, Zakaria MN. Heme oxygenase-1 alleviates vascular complications associated with metabolic syndrome: Effect on endothelial dependent relaxation and NO production. Chem Biol Interact 2014; 223:109-15. [DOI: 10.1016/j.cbi.2014.09.014] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2014] [Revised: 09/17/2014] [Accepted: 09/22/2014] [Indexed: 11/29/2022]
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Difference in cerebral blood flow velocity in neonates with and without hyperbilirubinemia. J Epidemiol Glob Health 2014; 4:97-106. [PMID: 24857177 PMCID: PMC7366370 DOI: 10.1016/j.jegh.2013.09.008] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2013] [Revised: 09/27/2013] [Accepted: 09/27/2013] [Indexed: 11/21/2022] Open
Abstract
PURPOSE To evaluate the difference in cerebral blood flow velocity (CBFV) in neonates with and without hyperbilirubinemia. METHODS CBFV of 70 healthy late-preterm and term newborns with unconjugated hyperbilirubinemia (UCH) reaching the threshold of phototherapy requirement was compared with 70 gestational- and postnatal age-matched controls without hyperbilirubinemia. Resistance index (RI), pulsatility index (PI), peak systolic velocity (PSV) and vascular diameter were measured in internal carotid, vertebral and middle cerebral arteries by transcranial color Doppler ultrasound at the beginning of phototherapy, after 48-72h of starting phototherapy and at 5-7days after its stoppage. In controls CBFV was assessed once at inclusion. RESULTS Both the groups were comparable. An increase in CBFV (decreased RI and PI, increased PSV and vasodilation) was observed in the UCH group. A further increase in CBFV was noticed after 48h of phototherapy. After 5-7days of stoppage of phototherapy, though there was a significant reduction in CBFV in mild-to-moderate UCH (serum bilirubin ⩽25mg/dL), in severe UCH (serum bilirubin >25mg/dL), CBFV remained increased. Four neonates developed features of acute bilirubin encephalopathy and had significantly higher CBFV compared to those with normal outcome. CONCLUSIONS An increase in CBFV was observed in neonates with UCH compared to those without hyperbilirubinemia.
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16
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Arngrim N, Schytz HW, Hauge MK, Ashina M, Olesen J. Carbon monoxide may be an important molecule in migraine and other headaches. Cephalalgia 2014; 34:1169-80. [DOI: 10.1177/0333102414534085] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Introduction Carbon monoxide was previously considered to just be a toxic gas. A wealth of recent information has, however, shown that it is also an important endogenously produced signalling molecule involved in multiple biological processes. Endogenously produced carbon monoxide may thus play an important role in nociceptive processing and in regulation of cerebral arterial tone. Discussion Carbon monoxide-induced headache shares many characteristics with migraine and other headaches. The mechanisms whereby carbon monoxide causes headache may include hypoxia, nitric oxide signalling and activation of cyclic guanosine monophosphate pathways. Here, we review the literature about carbon monoxide-induced headache and its possible mechanisms. Conclusion We suggest, for the first time, that carbon monoxide may play an important role in the mechanisms of migraine and other headaches.
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Affiliation(s)
- Nanna Arngrim
- Danish Headache Center and Department of Neurology, Glostrup Hospital, Faculty of Health and Medical Sciences, University of Copenhagen, Denmark
| | - Henrik W Schytz
- Danish Headache Center and Department of Neurology, Glostrup Hospital, Faculty of Health and Medical Sciences, University of Copenhagen, Denmark
| | - Mette K Hauge
- Danish Headache Center and Department of Neurology, Glostrup Hospital, Faculty of Health and Medical Sciences, University of Copenhagen, Denmark
| | - Messoud Ashina
- Danish Headache Center and Department of Neurology, Glostrup Hospital, Faculty of Health and Medical Sciences, University of Copenhagen, Denmark
| | - Jes Olesen
- Danish Headache Center and Department of Neurology, Glostrup Hospital, Faculty of Health and Medical Sciences, University of Copenhagen, Denmark
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17
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Stobart JL, Anderson CM. Multifunctional role of astrocytes as gatekeepers of neuronal energy supply. Front Cell Neurosci 2013; 7:38. [PMID: 23596393 PMCID: PMC3622037 DOI: 10.3389/fncel.2013.00038] [Citation(s) in RCA: 171] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2013] [Accepted: 03/26/2013] [Indexed: 01/01/2023] Open
Abstract
Dynamic adjustments to neuronal energy supply in response to synaptic activity are critical for neuronal function. Glial cells known as astrocytes have processes that ensheath most central synapses and express G-protein-coupled neurotransmitter receptors and transporters that respond to neuronal activity. Astrocytes also release substrates for neuronal oxidative phosphorylation and have processes that terminate on the surface of brain arterioles and can influence vascular smooth muscle tone and local blood flow. Membrane receptor or transporter-mediated effects of glutamate represent a convergence point of astrocyte influence on neuronal bioenergetics. Astrocytic glutamate uptake drives glycolysis and subsequent shuttling of lactate from astrocytes to neurons for oxidative metabolism. Astrocytes also convert synaptically reclaimed glutamate to glutamine, which is returned to neurons for glutamate salvage or oxidation. Finally, astrocytes store brain energy currency in the form of glycogen, which can be mobilized to produce lactate for neuronal oxidative phosphorylation in response to glutamatergic neurotransmission. These mechanisms couple synaptically driven astrocytic responses to glutamate with release of energy substrates back to neurons to match demand with supply. In addition, astrocytes directly influence the tone of penetrating brain arterioles in response to glutamatergic neurotransmission, coordinating dynamic regulation of local blood flow. We will describe the role of astrocytes in neurometabolic and neurovascular coupling in detail and discuss, in turn, how astrocyte dysfunction may contribute to neuronal bioenergetic deficit and neurodegeneration. Understanding the role of astrocytes as a hub for neurometabolic and neurovascular coupling mechanisms is a critical underpinning for therapeutic development in a broad range of neurodegenerative disorders characterized by chronic generalized brain ischemia and brain microvascular dysfunction.
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Affiliation(s)
- Jillian L Stobart
- Division of Neurodegenerative Disorders, Department of Pharmacology and Therapeutics, St. Boniface Hospital Research, University of Manitoba Winnipeg, MB, Canada ; Department of Nuclear Medicine, Institute of Pharmacology and Toxicology, University of Zürich Zürich, Switzerland
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18
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Hassan N, El-Bassossy HM, Zakaria MNM. Heme oxygenase-1 induction protects against hypertension associated with diabetes: effect on exaggerated vascular contractility. Naunyn Schmiedebergs Arch Pharmacol 2012; 386:217-26. [PMID: 23254361 DOI: 10.1007/s00210-012-0822-3] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2012] [Accepted: 12/04/2012] [Indexed: 12/14/2022]
Abstract
Disturbances in vascular reactivity are important components of diabetes-evoked hypertension. Heme oxygenase-1 (HO-1) is a homeostatic enzyme upregulated in stress. This study aims to investigate the protective effect of HO-1 against diabetes-evoked hypertension. Rats were left 8 weeks after diabetes induction with streptozotocin to induce vascular dysfunction in the diabetic groups. HO-1 inducers, hemin and curcumin, were daily administrated in the last 6 weeks in the treated groups after 2 weeks of induction. Then, at the end of the study (8 weeks), HO-1 protein level was assessed by immunofluorescence; blood pressure (BP) was recorded; isolated aorta reactivity to phenylephrine (PE) and KCl was studied; reactive oxygen species (ROS) generation was determined; and serum level of glucose, advanced glycation end products (AGEs), and tumor necrosis factor alpha (TNF-α) were determined. While not affected by diabetes, HO-1 protein expression was strongly induced by hemin or curcumin administration. Compared with control animals, diabetes increased systolic and pulse BP. Induction of HO-1 by hemin or curcumin significantly reduced elevated systolic BP and abolished elevated pulse BP without affecting the developed hyperglycemia or AGEs level. The possibility that alterations in vascular reactivity contributed to diabetes-HO-1 BP interaction was investigated. Diabetes increased contractile response of the aorta to PE and KCl, while HO-1 induction by curcumin or hemin prevented aorta-exaggerated response to PE and KCl. Furthermore, the competitive HO inhibitor, tin protoporphyrin, abolished the protective effect of hemin. Diabetes was accompanied with elevated level of TNF-α and ROS generation, while HO-1 induction abrogated increased TNF-α and ROS generation. Collectively, induction of HO-1 protects against hypertension associated with diabetes via ameliorating exaggerated vascular contractility by reducing TNF-α and aortic ROS levels.
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Affiliation(s)
- N Hassan
- Department of Pharmacology, Faculty of Pharmacy, Zagazig University, Zagazig, Egypt
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19
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Ndisang JF, Jadhav A, Lane N. Interaction between the heme oxygenase system and aldosterone in hypertension. Int J Angiol 2012; 16:92-7. [PMID: 22477300 DOI: 10.1055/s-0031-1278257] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
The chronic intraperitoneal administration of the heme oxygenase inducer, hemin (15 mg/kg daily), for three weeks reduced blood pressure in adult spontaneously hypertensive rats (SHR) from 210.1±1.03 mmHg to 127±0.9 mmHg (n=10, P<0.01) but had no effect on age-matched normotensive Wistar-Kyoto or Sprague-Dawley strains. The antihypertensive effect of hemin was accompanied by reduced expression of aldosterone synthase messenger RNA and depleted levels of plasma aldosterone (675.7±121.6 pg/mL versus 365.7±37 pg/mL; n=4, P<0.05).Because aldosterone is known to stimulate phospholipase C (PLC), the effect of hemin on PLC was examined. Hemin abated PLC activity (29.6±1.5 nmol/min/mL versus 3.1±0.9 nmol/min/mL; n=5, P<0.01) and this was accompanied by depleted levels of intracellular calcium (551±46 nM versus 103.2±6.3 nM; n=4, P<0.01) in the aorta of SHR. In contrast, enhanced heme oxygenase activity and elevated cyclic GMP levels (17.74±0.08 pmol/mg versus 30.4±2.3 pmol/mg protein; n=6, P<0.01) were detected in hemin-treated SHR. Additionally, hemin therapy also suppressed inflammatory and oxidative insults by significantly reducing nuclear factor kappa B messenger RNA expression while enhancing the total antioxidant capacity (0.22±0.02 Trolox equivalent antioxidant capacity (TEA C)/mg protein versus 0.60±0.04 TEA C/mg protein; n=4, P<0.01).The concomitant depletion of aldosterone, PLC activity, intracellular calcium and the corresponding decline of inflammatory and oxidative insults may account for the antihypertensive effects of hemin.
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20
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Qi M, Hang C, Zhu L, Shi J. Involvement of endothelial-derived relaxing factors in the regulation of cerebral blood flow. Neurol Sci 2011; 32:551-7. [PMID: 21584736 DOI: 10.1007/s10072-011-0622-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2011] [Accepted: 05/05/2011] [Indexed: 11/30/2022]
Abstract
Despite numerous researches and advances in the present times, delayed cerebral vasospasm remains a severe complication leading to a high mortality and morbidity in patients with subarachnoid hemorrhage (SAH). Since the discovery of endothelium-derived relaxing factor (EDRF) in 1980, its role in delayed cerebral vasospasm after SAH has been widely investigated as well as in regulation of basic cerebral blood flow, pathophysiology of vasoconstriction and application on prevention and treatment of cerebral vasospasm. Among all the EDRFs, nitric oxide has caught the most attention, and the other substances which display similar properties with characteristics of EDRF such as carbon monoxide (CO), hydrogen sulfide (H(2)S), hydrogen peroxide (H(2)O(2)), potassium ion (K(+)) and methane (CH(4)) have also evoked great interest in the research field. This review provides an overview of recent advances in investigations on the involvement of EDRFs in the regulation of cerebral blood flow, especially in cerebral vasospasm after SAH. Possible therapeutic measures and potential clinical implications for cerebral vasospasm are also summarized.
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Affiliation(s)
- Meng Qi
- Department of Neurosurgery, Jinling Hospital, Nanjing University Medical School, Nanjing, 210002, Jiangsu, China.
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21
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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] [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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22
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Abstract
Carbon monoxide is rapidly emerging as an important cellular messenger, regulating a wide range of physiological processes. Crucial to its role in both physiology and disease is its ability differentially to regulate several classes of ion channels, including examples from calcium-activated K(+) (BK(Ca)), voltage-activated K(+) (K(v)) and Ca(2+) channel (L-type) families, ligand-gated P2X receptors (P2X2 and P2X4), tandem P domain K(+) channels (TREK1) and the epithelial Na(+) channel (ENaC). The mechanisms by which CO regulates these ion channels are still unclear and remain somewhat controversial. However, available structure-function studies suggest that a limited range of amino acid residues confer CO sensitivity, either directly or indirectly, to particular ion channels and that cellular redox state appears to be important to the final integrated response. Whatever the molecular mechanism by which CO regulates ion channels, endogenous production of this gasotransmitter has physiologically important roles and is currently being explored as a potential therapeutic.
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Affiliation(s)
- William J Wilkinson
- Division of Pathophysiology and Repair, School of Biosciences, Cardiff University, Museum Avenue, Cardiff CF10 3AX, UK.
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23
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Leffler CW, Parfenova H, Jaggar JH. Carbon monoxide as an endogenous vascular modulator. Am J Physiol Heart Circ Physiol 2011; 301:H1-H11. [PMID: 21498777 DOI: 10.1152/ajpheart.00230.2011] [Citation(s) in RCA: 116] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
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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24
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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] [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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25
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Knecht KR, Leffler CW. Distinct effects of intravascular and extravascular angiotensin II on cerebrovascular circulation of newborn pigs. Exp Biol Med (Maywood) 2011; 235:1479-88. [PMID: 21127344 DOI: 10.1258/ebm.2010.010149] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Angiotensin II (AngII) is important in regulation of vascular resistance and control of blood flow among organs and tissues. The effect of AngII on the cerebral microvasculature may be mediated or altered by endothelial-derived signals. The aim of this study was to test the hypothesis that blood AngII dilates neonatal pial arterioles via an endothelial-dependent mechanism but brain AngII can constrict pial arterioles by activating smooth muscle AT1 receptors. Studies used anesthetized newborn pigs with surgically implanted closed cranial windows. AngII was given either by infusion into the carotid artery ipsilateral to the cranial window or topically. Intracarotid infusion of AngII dilated pial arterioles. The dilation was blocked by systemic administration of the AT1-receptor antagonist, losartan, but unaffected by topical losartan. Topical AngII also caused dilation, but this dilation was converted to constriction by topical losartan. In piglets pretreated with the angiotensin-converting enzyme (ACE) inhibitor, enalapril, topical AngII constricted, rather than dilated, pial arterioles. In enalapril-treated piglets, light/dye endothelial injury blocked dilation to intracarotid AngII but did not affect constriction to topical AngII. Either indomethacin or l-nitroarginine methyl ester blocked the dilation to intraluminal AngII, but neither affected constriction to topical AngII. Chromium mesoporphyrin, that inhibits heme oxygenase, did not affect responses to either topical or intravascular AngII. These data are consistent with the hypotheses that: (a) circulating AngII dilates pial arterioles via endothelial AT(1) receptor-derived relaxing factors, notably prostanoids and nitric oxide; (b) direct AT(1) receptor activation on the brain side of the blood-brain barrier by AngII causes AT(1) receptor-mediated constriction that can mask underlying AT(1) receptor-independent dilation when ACE is inhibited. Clinical manipulation of the renin-angiotensin system will have disparate actions on cerebral circulation depending on the functional integrity of the intima and ACE.
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Affiliation(s)
- Kenneth R Knecht
- Department of Pediatrics, University of Tennessee Center for the Health Sciences, Memphis, TN 38163, USA
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27
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Kajimura M, Fukuda R, Bateman RM, Yamamoto T, Suematsu M. Interactions of multiple gas-transducing systems: hallmarks and uncertainties of CO, NO, and H2S gas biology. Antioxid Redox Signal 2010; 13:157-92. [PMID: 19939208 PMCID: PMC2925289 DOI: 10.1089/ars.2009.2657] [Citation(s) in RCA: 219] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The diverse physiological actions of the "biologic gases," O2, CO, NO, and H2S, have attracted much interest. Initially viewed as toxic substances, CO, NO, and H2S play important roles as signaling molecules. The multiplicity of gas actions and gas targets and the difficulty in measuring local gas concentrations obscures detailed mechanisms whereby gases exert their actions, and many questions remain unanswered. It is now readily apparent, however, that heme-based proteins play central roles in gas-generation/reception mechanisms and provide a point where multiple gases can interact. In this review, we consider a number of key issues related to "gas biology," including the effective tissue concentrations of these gases and the importance and significance of the physical proximity of gas-producing and gas-receptor/sensors. We also take an integrated approach to the interaction of gases by considering the physiological significance of CO, NO, and H2S on mitochondrial cytochrome c oxidase, a key target and central mediator of mitochondrial respiration. Additionally, we consider the effects of biologic gases on mitochondrial biogenesis and "suspended animation." By evaluating gas-mediated control functions from both in vitro and in vivo perspectives, we hope to elaborate on the complex multiple interactions of O2, NO, CO, and H2S.
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Affiliation(s)
- Mayumi Kajimura
- Department of Biochemistry and Integrative Medical Biology, School of Medicine, Keio University , Tokyo, Japan.
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28
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Abstract
Endothelial dysfunction can develop at an early age in children with risk factors for cardiovascular disease. A clear understanding of the nature of this dysfunction and how it can worsen over time requires detailed information on the normal growth-related changes in endothelial function on which the pathological changes are superimposed. This review summarizes our current understanding of these normal changes, as derived from studies in four different mammalian species. Although the endothelium plays an important role in controlling vascular tone from birth onward, the vasoactive molecules that mediate this control often change during postnatal or juvenile growth. The specifics of this transition to an adult endothelial cell phenotype can vary depending on the vascular bed. During growth, the contribution of nitric oxide to endothelium-dependent dilation generally increases in the lung, cerebral cortex, and skeletal muscle, but decreases in the intestine. Endothelial capacity for release of other vasoactive factors (e.g., cyclooxygenase products, hydrogen peroxide, carbon monoxide) can also increase or decrease during growth. Although these changes have been well documented, there is less information on their underlying cellular or molecular events. Further research is required to clarify these mechanisms, and to evaluate the functional significance of such shifts in endothelial phenotype.
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MESH Headings
- Animals
- Animals, Newborn
- Cardiovascular Diseases/etiology
- Cardiovascular Diseases/physiopathology
- Cerebrovascular Circulation/physiology
- Endothelium, Vascular/growth & development
- Endothelium, Vascular/physiology
- Enterocolitis, Necrotizing/etiology
- Enterocolitis, Necrotizing/physiopathology
- Humans
- Infant, Newborn
- Intestines/blood supply
- Models, Animal
- Muscle, Skeletal/blood supply
- Muscle, Smooth, Vascular/growth & development
- Muscle, Smooth, Vascular/physiology
- Nitric Oxide/physiology
- Persistent Fetal Circulation Syndrome/etiology
- Persistent Fetal Circulation Syndrome/physiopathology
- Pulmonary Circulation/physiology
- Rats
- Risk Factors
- Sheep
- Swine
- Vascular Resistance/physiology
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Affiliation(s)
- Matthew A Boegehold
- Department of Physiology and Pharmacology and Center for Cardiovascular and Respiratory Sciences, Robert C. Byrd Health Sciences Center, West Virginia University School of Medicine, Morgantown, WV 26505-9105, USA.
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29
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Mechanistic electronic model to simulate and predict the effect of heat stress on the functional genomics of HO-1 system: Vasodilation. Comput Biol Med 2010; 40:533-42. [DOI: 10.1016/j.compbiomed.2010.03.011] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2008] [Revised: 03/24/2010] [Accepted: 03/25/2010] [Indexed: 11/20/2022]
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Knecht KR, Milam S, Wilkinson DA, Fedinec AL, Leffler CW. Time-dependent action of carbon monoxide on the newborn cerebrovascular circulation. Am J Physiol Heart Circ Physiol 2010; 299:H70-5. [PMID: 20435844 DOI: 10.1152/ajpheart.00258.2010] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Carbon monoxide (CO) causes cerebral arteriolar dilation in newborn pigs by the activation of large-conductance Ca(2+)-activated K(+) channels. In adult rat cerebral and skeletal muscle arterioles, CO has been reported to produce constriction caused by the inhibition of nitric oxide (NO) synthase (NOS). We hypothesized that, in contrast to dilation to acute CO, more prolonged exposure of newborn cerebral arterioles to elevated CO produces constriction by reducing NO. In piglets with closed cranial windows, pial arteriolar responses to isoproterenol (10(-6) M), sodium nitroprusside (SNP; 10(-7) and 3 x 10(-7) M), and L-arginine ethyl ester (L-Arg; 10(-5) and 10(-4) M) were determined before and after 2 h of treatment with CO. CO (10(-7) M) caused transient dilation and had no further effects. CO (2 x 10(-7) and 10(-6) M) initially caused vasodilation, but over the 2-h exposure, pial arterioles constricted and removal of the CO caused dilation. Exposure to elevated CO (2 h) did not alter dilation to SNP or isoproterenol. Conversely, the NOS substrate L-Arg caused dilation before CO that was progressively lost over 90 min of elevated CO. If NO was held constant, CO caused dilation that was sustained for 2 h. We conclude that in neonates, cerebral arteriole responses to CO are biphasic: dilation to acute elevation with subsequent constriction from NOS inhibition after more prolonged exposure. As a result, short episodic production of CO allows function as a dilator gasotransmitter, whereas prolonged elevation can reduce NO to elevate cerebrovascular tone. The interaction between heme oxygenase/CO and NOS/NO could form a negative feedback system in the control of cerebral vascular tone.
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Affiliation(s)
- Kenneth R Knecht
- Department of Physiology, University of Tennessee Health Science Center, 894 Union Ave., Memphis, TN 38163, USA
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31
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Abraham NG, Cao J, Sacerdoti D, Li X, Drummond G. Heme oxygenase: the key to renal function regulation. Am J Physiol Renal Physiol 2009; 297:F1137-52. [PMID: 19570878 PMCID: PMC2781329 DOI: 10.1152/ajprenal.90449.2008] [Citation(s) in RCA: 78] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2008] [Accepted: 06/09/2009] [Indexed: 02/07/2023] Open
Abstract
Heme oxygenase (HO) plays a critical role in attenuating the production of reactive oxygen species through its ability to degrade heme in an enzymatic process that leads to the production of equimolar amounts of carbon monoxide and biliverdin/bilirubin and the release of free iron. The present review examines the beneficial role of HO-1 (inducible form of HO) that is achieved by increased expression of this enzyme in renal tissue. The influence of the HO system on renal physiology, obesity, vascular dysfunction, and blood pressure regulation is reviewed, and the clinical potential of increased levels of HO-1 protein, HO activity, and HO-derived end products of heme degradation is discussed relative to renal disease. The use of pharmacological and genetic approaches to investigate the role of the HO system in the kidney is key to the development of therapeutic approaches to prevent the adverse effects that accrue due to an impairment in renal function.
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Affiliation(s)
- Nader G Abraham
- New York Medical College, Department of Pharmacology, Valhalla, NY 10595, USA.
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Samora JB, Goodwill AG, Frisbee JC, Boegehold MA. Growth-dependent changes in the contribution of carbon monoxide to arteriolar function. J Vasc Res 2009; 47:23-34. [PMID: 19672105 DOI: 10.1159/000231718] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2008] [Accepted: 12/31/2008] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND/AIMS Endothelium-dependent dilation of skeletal muscle arterioles is mediated by unknown factors in very young rats. We assessed the possible contribution of carbon monoxide (CO) to this dilation and to dilation in older animals. METHODS The effects of de-endothelialization or various pharmacological inhibitors on responses to CO or endothelium-dependent dilators were studied in gracilis muscle arterioles from rats at 3-4 weeks ('weanlings') and 6-7 weeks ('juveniles'). RESULTS Exogenous CO constricted, rather than dilated, arterioles from both age groups. This constriction was reduced by endothelial removal or NOS inhibition in juvenile, but not weanling, arterioles. In contrast, this constriction was abolished by K(+) channel inhibition in weanling, but not juvenile, arterioles. The heme precursor delta-aminolevulinic acid constricted juvenile arterioles but did not affect weanling arterioles. The heme oxygenase inhibitor chromium (III) mesoporphyrin IX abolished the endothelium-dependent dilation of juvenile arterioles to simvastatin, and reduced ACh- and simvastatin-induced dilations of weanling arterioles. CONCLUSION These findings suggest that relatively high concentrations of exogenous CO can cause constriction by inhibiting endothelium-derived NO in juvenile arterioles and inhibiting K(+) channels in weanling arterioles. Endogenous CO produced at lower concentrations can contribute to endothelium-dependent dilation in both age groups.
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Affiliation(s)
- Julie Balch Samora
- Department of Physiology and Pharmacology, and Center for Interdisciplinary Research in Cardiovascular Sciences, West Virginia University School of Medicine, Morgantown, W. Va., USA
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Kanu A, Leffler CW. Roles of glia limitans astrocytes and carbon monoxide in adenosine diphosphate-induced pial arteriolar dilation in newborn pigs. Stroke 2009; 40:930-5. [PMID: 19164779 DOI: 10.1161/strokeaha.108.533786] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND AND PURPOSE Astrocytes, neurons, and microvessels together form a neurovascular unit allowing blood flow to match neuronal activity. Adenosine diphosphate (ADP) is an important signaling molecule in the brain, and dilation in response to ADP is astrocyte-dependent in rats and newborn pigs. Carbon monoxide (CO), produced endogenously by catabolism of heme to CO, iron, and biliverdin via heme oxygenase, is an important cell-signaling molecule in the neonatal cerebral circulation. We hypothesize ADP stimulates CO production by glia limitans astrocytes and that this CO causes pial arteriolar dilation. METHODS Experiments were performed using anesthetized piglet with closed cranial windows, and freshly isolated piglet astrocytes and microvessels. Astrocyte injury was caused by topical application of L-2-alpha aminoadipic acid (2 mmol/L, 5 hours). Cerebrospinal fluid was collected from under the cranial windows for measurement of ADP-stimulated CO production. CO was measured by gas chromatography-mass spectroscopy analysis. RESULTS Before, but not after, astrocyte injury in vivo, topical ADP stimulated both CO production and dilation of pial arterioles. Astrocyte injury did not block dilation to isoproterenol or bradykinin. Chromium mesoporphyrin, an inhibitor of heme oxygenase, also prevented the ADP-induced increase in cerebrospinal fluid CO and pial arteriolar dilation caused by ADP, but not dilation to sodium nitroprusside. ADP also increased CO production by freshly isolated piglet astrocytes and cerebral microvessels, although the increase was smaller in the microvessels. CONCLUSIONS These data suggest that glia limitans astrocytes use CO as a gasotransmitter to cause pial arteriolar dilation in response to ADP.
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Affiliation(s)
- Alie Kanu
- Laboratory for Research in Neonatal Physiology, Department of Physiology, University of Tennessee Health Science Center, Memphis, Tenn., USA
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Loboda A, Jazwa A, Grochot-Przeczek A, Rutkowski AJ, Cisowski J, Agarwal A, Jozkowicz A, Dulak J. Heme oxygenase-1 and the vascular bed: from molecular mechanisms to therapeutic opportunities. Antioxid Redox Signal 2008; 10:1767-812. [PMID: 18576916 DOI: 10.1089/ars.2008.2043] [Citation(s) in RCA: 200] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Heme oxygenase-1, an enzyme degrading heme to carbon monoxide, iron, and biliverdin, has been recognized as playing a crucial role in cellular defense against stressful conditions, not only related to heme release. HO-1 protects endothelial cells from apoptosis, is involved in blood-vessel relaxation regulating vascular tone, attenuates inflammatory response in the vessel wall, and participates in blood-vessel formation by means of angiogenesis and vasculogenesis. The latter functions link HO-1 not only to cardiovascular ischemia but also to many other conditions that, like development, wound healing, or cancer, are dependent on neovascularization. The aim of this comprehensive review is to address the mechanisms of HO-1 regulation and function in cardiovascular physiology and pathology and to demonstrate some possible applications of the vast knowledge generated so far. Recent data provide powerful evidence for the involvement of HO-1 in the therapeutic effect of drugs used in cardiovascular diseases. Novel studies open the possibilities of application of HO-1 for gene and cell therapy. Therefore, research in forthcoming years should help to elucidate both the real role of HO-1 in the effect of drugs and the clinical feasibility of HO-1-based cell and gene therapy, creating the effective therapeutic avenues for this refined antioxidant system.
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Affiliation(s)
- Agnieszka Loboda
- Department of Medical Biotechnology, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Krakow, Poland
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Corrigendum. Am J Physiol Heart Circ Physiol 2008. [DOI: 10.1152/ajpheart.zh4-8475-corr.2008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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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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Li A, Xi Q, Umstot ES, Bellner L, Schwartzman ML, Jaggar JH, Leffler CW. Astrocyte-derived CO is a diffusible messenger that mediates glutamate-induced cerebral arteriolar dilation by activating smooth muscle Cell KCa channels. Circ Res 2007; 102:234-41. [PMID: 17991880 DOI: 10.1161/circresaha.107.164145] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Astrocyte signals can modulate arteriolar tone, contributing to regulation of cerebral blood flow, but specific intercellular communication mechanisms are unclear. Here we used isolated cerebral arteriole myocytes, astrocytes, and brain slices to investigate whether carbon monoxide (CO) generated by the enzyme heme oxygenase (HO) acts as an astrocyte-to-myocyte gasotransmitter in the brain. Glutamate stimulated CO production by astrocytes with intact HO-2, but not those genetically deficient in HO-2. Glutamate activated transient K(Ca) currents and single K(Ca) channels in myocytes that were in contact with astrocytes, but did not affect K(Ca) channel activity in myocytes that were alone. Pretreatment of astrocytes with chromium mesoporphyrin (CrMP), a HO inhibitor, or genetic ablation of HO-2 prevented glutamate-induced activation of myocyte transient K(Ca) currents and K(Ca) channels. Glutamate decreased arteriole myocyte intracellular Ca2+ concentration and dilated brain slice arterioles and this decrease and dilation were blocked by CrMP. Brain slice arteriole dilation to glutamate was also blocked by L-2-alpha aminoadipic acid, a selective astrocyte toxin, and paxilline, a K(Ca) channel blocker. These data indicate that an astrocytic signal, notably HO-2-derived CO, is used by glutamate to stimulate arteriole myocyte K(Ca) channels and dilate cerebral arterioles. Our study explains the astrocyte and HO dependence of glutamatergic functional hyperemia observed in the newborn cerebrovascular circulation in vivo.
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Affiliation(s)
- Anlong Li
- Department of Physiology, University of Tennessee Health Science Center, Memphis, USA
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Kanu A, Leffler CW. Carbon monoxide and Ca2+-activated K+ channels in cerebral arteriolar responses to glutamate and hypoxia in newborn pigs. Am J Physiol Heart Circ Physiol 2007; 293:H3193-200. [PMID: 17766483 PMCID: PMC2435509 DOI: 10.1152/ajpheart.00274.2007] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Large-conductance calcium-activated potassium (K(Ca)) channels regulate the physiological functions of many tissues, including cerebrovascular smooth muscle. l-Glutamic acid (glutamate) is the principal excitatory neurotransmitter in the central nervous system, and oxygen tension is a dominant local regulator of vascular tone. In vivo, glutamate and hypoxia dilate newborn pig cerebral arterioles, and both dilations are blocked by inhibition of carbon monoxide (CO) production. CO dilates cerebral arterioles by activating K(Ca) channels. Therefore, the present study was designed to investigate the effects of glutamate and hypoxia on cerebral CO production and the role of K(Ca) channels in the cerebral arteriolar dilations to glutamate and hypoxia. In the presence of iberiotoxin or paxilline that block dilation to the K(Ca) channel opener, NS-1619, neither CO nor glutamate dilated pial arterioles. Conversely, neither paxilline nor iberiotoxin inhibited dilation to acute severe or moderate prolonged hypoxia. Both glutamate and hypoxia increased cerebrospinal fluid (CSF) CO concentration. Iberiotoxin that blocked dilation to glutamate did not attenuate the increase in CSF CO. The guanylyl cyclase inhibitor, 1H-(1,2,4)oxadiazolo(4,3-a)quinoxalin-1-one (ODQ), which blocked dilation to sodium nitroprusside, did not inhibit dilation to hypoxia. These data suggest that dilation of newborn pig pial arterioles to glutamate is mediated by activation of K(Ca) channels, consistent with the intermediary signal being CO. Surprisingly, although 1) heme oxygenase (HO) inhibition attenuates dilation to hypoxia, 2) hypoxia increases CSF CO concentration, and 3) K(Ca) channel antagonists block dilation to CO, neither K(Ca) channel blockers nor ODQ altered dilation to hypoxia, suggesting the contribution of the HO/CO system to hypoxia-induced dilation is not by stimulating vascular smooth muscle K(Ca) channels or guanylyl cyclase.
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Affiliation(s)
- Alie Kanu
- Laboratory for Resaerch in Neonatal Physiology, Department of Physiology, University of Tennessee Health Science Center, Memphis, TN, USA
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Bauer R, Walter B, Brandl U. Intrauterine growth restriction improves cerebral O2 utilization during hypercapnic hypoxia in newborn piglets. J Physiol 2007; 584:693-704. [PMID: 17717008 PMCID: PMC2277152 DOI: 10.1113/jphysiol.2007.142778] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Data are scant regarding the capacity of cerebrovascular regulation during asphyxia for prevention of brain oxygen deficit in intrauterine growth-restricted (IUGR) newborns. We tested the hypothesis that IUGR improves the ability of neonates to withstand critical periods of severe asphyxia by optimizing brain oxygen supply. Studies were conducted to examine the effects of IUGR on cerebral blood flow (CBF) regulation and oxygen consumption (cerebral metabolic rate for oxygen, CMRO(2)) at different stages of asphyxia (hypercapnic hypoxaemia) in comparison to pure hypoxia (normocapnic hypoxaemia). We used 1-day-old anaesthetized and ventilated piglets. Animals were divided into normal weight (NW) piglets (n = 47; aged 11-26 h, body weight 1481 +/- 121 g) and IUGR piglets (n = 48; aged 13-28 h, body weight 806 +/- 42 g) according to their birth weight. Different stages of hypoxaemia were induced for 1 h by appropriate lowering of the inspired fraction of oxygen (moderate hypoxia: = 31-34 mmHg; severe hypoxia: = 20-22 mmHg). Fourteen NW and 16 IUGR piglets received additionally 9% CO(2) in the breathing gas, so that a of 74-80 mmHg resulted (hypoxia/hypercapnia groups). Eight NW and nine IUGR animals served as untreated controls. Furthermore, affinity of haemoglobin for oxygen was measured under hypoxic and asphyxic conditions. During asphyxia cerebral oxygen extraction was markedly increased in IUGR animals (P < 0.05). This resulted in a significantly diminished CMRO(2)-related increase of CBF at gradually reduced arterial oxygen content (P < 0.05). Therefore, an enhanced effectivity in oxygen availability appeared in newborn IUGR piglets under graded asphyxia by improved cerebral oxygen utilization (P < 0.05). This was not supported by related O(2) affinity of haemoglobin. Thus, IUGR newborns are more capable to ensure brain O(2) demand during asphyxia (hypercapnic hypoxia) than NW neonates.
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Affiliation(s)
- Reinhard Bauer
- Institute of Molecular Cell Biology, Center for Molecular Biomedicine, and Department of Neuropaediatrics, Children's Hospital, Friedrich Schiller University, D-07740 Jena, Germany.
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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] [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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Kanu A, Whitfield J, Leffler CW. Carbon monoxide contributes to hypotension-induced cerebrovascular vasodilation in piglets. Am J Physiol Heart Circ Physiol 2006; 291:H2409-14. [PMID: 16751286 PMCID: PMC1593219 DOI: 10.1152/ajpheart.01368.2005] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The gaseous compound carbon monoxide (CO) has been identified as an important endogenous biological messenger in brain and is a major component in regulation of cerebrovascular circulation in newborns. CO is produced endogenously by catabolism of heme to CO, free iron, and biliverdin during enzymatic degradation of heme by heme oxygenase (HO). The present study was designed to test the hypothesis that endogenously produced CO contributes to hypotension-induced vasodilation of cerebral arterioles. Experiments used anesthetized piglets with implanted, closed cranial windows. Topical application of the HO substrate heme-l-lysinate caused dilation of pial arterioles that was blocked by a metal porphyrin inhibitor of HO, chromium mesoporphyrin (CrMP). In normotensive piglets (arterial pressure 64 +/- 4 mmHg), CrMP did not cause vasoconstriction of pial arterioles but rather a transient dilation. Hypotension (50% of basal blood pressure) increased cerebral CO production and dilated pial arterioles from 66 +/- 2 to 92 +/- 7 microm. In hypotensive piglets, topical CrMP or intravenous tin protoporphyrin decreased cerebral CO production and produced pial arteriolar constriction to normotensive diameters. In additional experiments, because prostacyclin and nitric oxide (NO) are also key dilators that can contribute to cerebrovascular dilation, we held their levels constant. NO/prostacyclin clamp was accomplished with continuous, simultaneous application of indomethacin, N(omega)-nitro-l-arginine, and minimal dilatory concentrations of iloprost and sodium nitroprusside. With constant NO and prostacyclin, the transient dilator and prolonged constrictor responses to CrMP of normotensive and hypotensive piglets, respectively, were the same as when NO and prostaglandins were not held constant. These data suggest that endogenously produced CO contributes to cerebrovascular dilation in response to reduced perfusion pressure.
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Affiliation(s)
- Alie Kanu
- Dept. of Physiology, Univ. of Tennessee Health Science Center, 894 Union Ave, Memphis, TN 38163, USA
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Wang R, Shamloul R, Wang X, Meng Q, Wu L. Sustained normalization of high blood pressure in spontaneously hypertensive rats by implanted hemin pump. Hypertension 2006; 48:685-92. [PMID: 16940218 DOI: 10.1161/01.hyp.0000239673.80332.2f] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Treatment of established hypertension, especially for prolonged control of this pathogenic process, represents a great challenge. To upregulate the expression of heme oxygenase (HO) to lower blood pressure (BP) of spontaneously hypertensive rats (SHRs), we administered hemin to 12-week-old adult SHRs through subcutaneously implanted osmotic minipumps for 3 consecutive weeks (the hemin protocol). Systolic BP of SHRs was normalized 123+/-2 mm Hg (n=20; P<0.001) and this normalization maintained for 9 months after the removal of hemin pumps. At the end of the hemin protocol, HO-1 expression, HO activity, soluble guanylyl cyclase expression, and cGMP content were all increased, but phosphodiesterase-5 expression was downregulated in the mesenteric arteries. The hemin protocol also reversed SHR-featured arterial eutrophic inward remodeling and decreased expression levels of vascular endothelial growth factor. These changes lasted 9 months after the hemin protocol. Our study, thus, formulates a novel hemin protocol that will not only normalize BP in SHRs with established hypertension but, more importantly, will also provide long-lasting antihypertension protection. Sustained upregulation of HO-1-linked signaling pathways and reversal of vascular remodeling in peripheral blood vessels mediate likely the antihypertensive effect of the hemin protocol.
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Affiliation(s)
- Rui Wang
- Department of Physiology, University of Saskatchewan, Saskatoon, Saskatchewan, Canada.
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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] [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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Naik JS, Walker BR. Role of vascular heme oxygenase in reduced myogenic reactivity following chronic hypoxia. Microcirculation 2006; 13:81-8. [PMID: 16459321 DOI: 10.1080/10739680500466301] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
OBJECTIVE Exposure to chronic hypoxia (CH) results in a persistent endothelium-dependent vascular smooth muscle hyperpolarization that diminishes vasoconstrictor reactivity. Experiments were performed to test the hypothesis that products of both cytochrome P450 epoxygenase (CYP) and heme oxygenase (HO) are required for the persistent diminished myogenic reactivity following CH. METHODS The authors examined myogenic responses of mesenteric arteries isolated from control and CH (48 h; P(B) = 380 mmHg) rats in the presence of a HO inhibitor (zinc protoporphyrin IX; ZnPPIX) or combined HO and CYP epoxygenase inhibition (sulfaphenazole). Arteries were isolated and cannulated and the vascular smooth muscle was loaded with the Ca2+ indicator Fura-2. RESULTS Control vessels maintained their internal diameter in response to step increases in intraluminal pressure, whereas arteries from CH animals passively distended. ZnPPIX augmented myogenic reactivity and [Ca2+] in arteries from CH animals. Combined administration of sulfaphenazole and ZnPPIX did not have an additional effect compared to ZnPPIX alone. Myogenic reactivity in control vessels was not altered by ZnPPIX or ZnPPIX + sulfaphenazole. CONCLUSIONS HO appears to play a role in regulating myogenic reactivity following CH. Furthermore, these data suggest that products of HO and CYP are both required for the observed attenuation in vasoreactivity following CH.
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Affiliation(s)
- Jay S Naik
- Vascular Physiology Group, Department of Cell Biology and Physiology, University of New Mexico Health Sciences Center, Albuquerque, New Mexico, USA
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Ryter SW, Alam J, Choi AMK. Heme oxygenase-1/carbon monoxide: from basic science to therapeutic applications. Physiol Rev 2006; 86:583-650. [PMID: 16601269 DOI: 10.1152/physrev.00011.2005] [Citation(s) in RCA: 1759] [Impact Index Per Article: 97.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
The heme oxygenases, which consist of constitutive and inducible isozymes (HO-1, HO-2), catalyze the rate-limiting step in the metabolic conversion of heme to the bile pigments (i.e., biliverdin and bilirubin) and thus constitute a major intracellular source of iron and carbon monoxide (CO). In recent years, endogenously produced CO has been shown to possess intriguing signaling properties affecting numerous critical cellular functions including but not limited to inflammation, cellular proliferation, and apoptotic cell death. The era of gaseous molecules in biomedical research and human diseases initiated with the discovery that the endothelial cell-derived relaxing factor was identical to the gaseous molecule nitric oxide (NO). The discovery that endogenously produced gaseous molecules such as NO and now CO can impart potent physiological and biological effector functions truly represented a paradigm shift and unraveled new avenues of intense investigations. This review covers the molecular and biochemical characterization of HOs, with a discussion on the mechanisms of signal transduction and gene regulation that mediate the induction of HO-1 by environmental stress. Furthermore, the current understanding of the functional significance of HO shall be discussed from the perspective of each of the metabolic by-products, with a special emphasis on CO. Finally, this presentation aspires to lay a foundation for potential future clinical applications of these systems.
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Affiliation(s)
- Stefan W Ryter
- Department of Medicine, Division of Pulmonary, Allergy, and Critical Care Medicine, The University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA.
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Abstract
Many biological functions of heme oxygenase (HO), such as cytoprotection against oxidative stress, vasodilation, neurotransmission in the central or peripheral nervous systems, and anti-inflammatory, anti-apoptotic, or anti-proliferative potential, have been attributed to its enzymatic byproduct carbon monoxide (CO), although roles for biliverdin/bilirubin and iron have also been proposed. In addition to these well-characterized effects, recent findings reveal that HO-derived CO may act as an oxygen sensor and circadian modulator of heme biosynthesis. In lymphocytes, CO may participate in regulatory T cell function. A number of the known signaling effects of CO depend on stimulation of soluble guanylate cyclase and/or activation of mitogen-activated protein kinases (MAPK). Furthermore, modulation of caveolin-1 status may serve as an essential component of certain aspects of CO action, such as growth control. In this review, we summarize recent findings of the beneficial or detrimental effects of endogenous CO with an emphasis on the signaling pathways and downstream targets that trigger the action of this gas.
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Affiliation(s)
- Hong Pyo Kim
- Department of Medicine, Division of Pulmonary, Allergy and Critical Care Medicine, University of Pittsburgh, Pittsburgh, PA 15213, USA.
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Ohata H, Cao S, Koehler RC. Contribution of adenosine A2A and A2B receptors and heme oxygenase to AMPA-induced dilation of pial arterioles in rats. Am J Physiol Regul Integr Comp Physiol 2006; 291:R728-35. [PMID: 16601261 PMCID: PMC1764456 DOI: 10.1152/ajpregu.00757.2005] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Nitric oxide (NO) has been implicated in mediation of cerebral vasodilation during neuronal activation and, specifically, in pharmacological activation of N-methyl-d-aspartate (NMDA) and kainate receptors. Possible mediators of cerebral vasodilation to alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA) have not been well studied in mature brain, although heme oxygenase (HO) activity has been implicated in newborn pigs. In anesthetized rats, 5 min of topical superfusion of 30 and 100 microM AMPA on the cortical surface through a closed cranial window resulted in increases in pial arteriolar diameter. The dilatory response to AMPA was not inhibited by superfusion of an NO synthase inhibitor, a cyclooxygenase-2 inhibitor, or a cytochrome P-450 epoxygenase inhibitor, all of which have been shown to inhibit the cortical blood flow response to sensory activation. However, the 48 +/- 13% dilation to 100 microM AMPA was attenuated 56-71% by superfusion of the adenosine A(2A) receptor antagonist ZM-241385, the A(2B) receptor antagonist alloxazine, and the HO inhibitor chromium mesoporphyrin. Combination of the latter three inhibitors did not attenuate the dilator response more than the individual inhibitors, whereas an AMPA receptor antagonist fully blocked the vasodilation to AMPA. These results indicate that cortical pial arteriolar dilation to AMPA does not require activation of NO synthase, cyclooxygenase-2, or cytochrome P-450 epoxygenase but does depend on activation of adenosine A(2A) and A(2B) receptors. In addition, CO derived from HO appears to play a role in the vascular response to AMPA receptor activation in mature brain by a mechanism that is not additive with that of adenosine receptor activation.
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Affiliation(s)
- Hiroto Ohata
- Dept. of Anesthesiology and Critical Care Medicine, Johns Hopkins University, Baltimore, MD 21287-4961, USA
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Fu R, Zhao ZQ, Zhao HY, Zhao JS, Zhu XL. Expression of heme oxygenase-1 protein and messenger RNA in permanent cerebral ischemia in rats. Neurol Res 2006; 28:38-45. [PMID: 16464361 DOI: 10.1179/016164106x91852] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
Abstract
BACKGROUND Carbon monoxide has been regarded as a gaseous molecular messenger like nitric oxide. PURPOSE To clarify the role of heme oxygenase-1 in the permanent cerebral ischemia at the protein and mRNA level. METHODS The expression of heme oxygenase-1 protein and messenger RNA was investigated at different time points following MCAO using immunohistochemistry, Western blotting, RT-PCR, and Northern blotting. RESULTS Increased HO 1immunoreactivity was detected in hippocampal and cortical neurons after 1 hour of ischemia, and was also observed in astroglial cells. After 12 hours of ischemia, HO-1 was found in both neurons and glia in cerebral cortex and thalamus, and in striatal glia cells. Western blotting analysis show the expression of HO-1 protein in cortical neurons reached the peak after 12 hours of occlusion and decreased gradually, but was still detected at day 7 post-occlusion. The expression of messenger RNA was examined in the brains of rats subjected to permanent cerebral ischemia by semi-quantitative RT-PCR and Northern blotting. HO-1 mRNA transcription could be detected 1 hour after occlusion. After 1 to 6 hours of occlusion, the expression of HO-1 rose rapidly, reaching a peak at 12 hours post-occlusion, decreased gradually, and lasted until day 7 of occlusion. Although HO activity of cerebral tissue can be detected in both sham-operated group and operated groups, the HO activity in operated groups is much stronger than that in sham-operated group. CONCLUSIONS The induction of HO-1 protein may protect cerebral tissues from ischemic damage.
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Affiliation(s)
- Rong Fu
- Neurosurgery Department, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China.
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Kanu A, Gilpin D, Fedinec AL, Leffler CW. Cyclooxygenase products stimulate carbon monoxide production by piglet cerebral microvessels. Exp Biol Med (Maywood) 2006; 231:181-5. [PMID: 16446494 PMCID: PMC1360158 DOI: 10.1177/153537020623100208] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Products of arachidonic acid (AA) metabolism by cyclooxygenase (Cox) are important in regulation of neonatal cerebral circulation. The brain and cerebral microvessels also express heme oxygenase (HO) that metabolizes heme to carbon monoxide (CO), biliverdin, and iron. The purpose of this study in newborn pig cerebral microvessels was to address the hypothesis that Cox products affect HO activity and HO products affect Cox activity. AA (2.0-20 microM) increased prostaglandin E2 (PGE2) measured by radioimmunoassay (RIA) and also CO measured by gas chromatography/mass spectrometry (GC/MS). Further, 10(-4) M indomethacin, which inhibited Cox, reduced both AA and heme-induced CO production. Conversely, neither exogenous 2 x 10(-6) M heme, which markedly increased CO production, nor the inhibitor of HO, chromium mesoporphyrin, altered PGE2 synthesis. Because AA metabolism by Cox generates both prostanoids and superoxides, we determined the effects of the predominant prostanoid and superoxide on CO production. Although PGE2 caused a small increase in CO production, xanthine oxidase plus hypoxanthine, which produces superoxide, strongly stimulated the production of CO by cerebral microvessels. This increase was mildly attenuated by catalase. These data suggest that Cox-catalyzed AA metabolites, most likely superoxide and/or a subsequent reactive oxygen species, increase cerebrovascular CO production. This increase seems to be caused, at least in part, by the elevation of HO-2 catalytic activity. Conversely, Cox activity is not affected by HO-catalyzed heme metabolites. These data suggest that some cerebrovascular functions attributable to Cox activity could be mediated by CO.
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Affiliation(s)
- Alie Kanu
- Department of Physiology, University of Tennessee Health Science Center, Memphis, TN 38163, USA
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Leffler CW, Parfenova H, Jaggar JH, Wang R. Carbon monoxide and hydrogen sulfide: gaseous messengers in cerebrovascular circulation. J Appl Physiol (1985) 2006; 100:1065-76. [PMID: 16467393 PMCID: PMC1363746 DOI: 10.1152/japplphysiol.00793.2005] [Citation(s) in RCA: 157] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
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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