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Rapoport RM. Bilirubin Oxidation Products and Cerebral Vasoconstriction. Front Pharmacol 2018; 9:303. [PMID: 29755343 PMCID: PMC5934420 DOI: 10.3389/fphar.2018.00303] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2017] [Accepted: 03/15/2018] [Indexed: 01/15/2023] Open
Abstract
Key evidence in support of the hypothesis that bilirubin oxidation products (BOXes) contribute to the vasoconstriction associated with subarachnoid hemorrhage (SAH) are the (1) presence of BOXes in cerebral spinal fluid from SAH patients and (2) ability of one or more BOXes to elicit vasoconstriction. We critically evaluate this key evidence, detail where gaps remain, and describe recent approaches that will address these gaps.
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Affiliation(s)
- Robert M Rapoport
- Department of Pharmacology and Systems Physiology, College of Medicine, University of Cincinnati, Cincinnati, OH, United States
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Deng W, Kandhi S, Zhang B, Huang A, Koller A, Sun D. Extravascular Blood Augments Myogenic Constriction of Cerebral Arterioles: Implications for Hemorrhage-Induced Vasospasm. J Am Heart Assoc 2018; 7:JAHA.118.008623. [PMID: 29654195 PMCID: PMC6015404 DOI: 10.1161/jaha.118.008623] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Background Subarachnoid hemorrhage is a serious clinical condition that impairs local cerebral blood flow perfusion and consequently initiates neuronal dysfunction. Pressure‐sensitive myogenic vasomotor regulation is an important mechanism involved in the regulation of cerebral blood flow. We hypothesized that extravascular hemolyzed blood enhances arteriolar myogenic constriction, which in vivo may contribute to the reduction of local cerebral blood flow after subarachnoid hemorrhage. Methods and Results Arterioles isolated from the middle cerebral artery (MCA arterioles) of mice were cannulated in a perfusion chamber. Arteriolar diameters in response to step increases in intraluminal pressure (20–120 mm Hg) were measured in various experimental conditions. In response to increases in intraluminal pressure, all MCA arterioles exhibited myogenic vasoconstrictions. Compared with controls, the pressure‐induced constriction was significantly enhanced in arterioles (in vitro) exposed to extravascular hemolyzed blood or different concentrations of extracellular erythrocyte lysate (1%, 10%, and 20%) for different exposure durations (1–6 hours). The magnitude of enhancement was proportional to the lysate concentration and exposure duration. In in vivo experiments, 10 μL of autologous blood lysate were injected into the mouse subarachnoid space on the surface of the left MCA. Two hours later, MCA arterioles were isolated and left MCA arterioles displayed enhanced myogenic responses compared with the right MCA. The enhanced myogenic response was prevented by scavenge of superoxide in both in vitro and in vivo experiments. Conclusions Extravascular hemolyzed blood, perhaps by promoting vascular production of superoxide, augments myogenic constriction of cerebral arterioles, which plays a crucial role in the subarachnoid hemorrhage–induced cerebral ischemia.
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Affiliation(s)
- Wensheng Deng
- Department of Physiology, New York Medical College, Valhalla, NY.,Department of General Surgery, Shanghai Ninth People's Hospital, Shanghai, China
| | - Sharath Kandhi
- Department of Physiology, New York Medical College, Valhalla, NY
| | - Bin Zhang
- Department of Physiology, New York Medical College, Valhalla, NY.,Department of GI Surgery, Renji Hospital, School of Medicine, Shanghai Jiaotong University, Shanghai, China
| | - An Huang
- Department of Physiology, New York Medical College, Valhalla, NY
| | - Akos Koller
- Department of Physiology, New York Medical College, Valhalla, NY.,Institute of Natural Sciences, Sportgenetics and Sportgerontology Res. Group, University of Physical Education, Budapest, Hungary.,Department of Neurosurgery, Medical School, University of Pecs, Hungary
| | - Dong Sun
- Department of Physiology, New York Medical College, Valhalla, NY
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Cseplo P, Vamos Z, Ivic I, Torok O, Toth A, Koller A. The Beta-1-Receptor Blocker Nebivolol Elicits Dilation of Cerebral Arteries by Reducing Smooth Muscle [Ca2+]i. PLoS One 2016; 11:e0164010. [PMID: 27716772 PMCID: PMC5055296 DOI: 10.1371/journal.pone.0164010] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2015] [Accepted: 09/19/2016] [Indexed: 01/22/2023] Open
Abstract
Rationale Nebivolol is known to have beta-1 blocker activity, but it was also suggested that it elicits relaxation of the peripheral arteries in part via release of nitric oxide (NO). However, the effect of nebivolol on the vasomotor tone of cerebral arteries is still unclear. Objective To assess the effects of nebivolol on the diameter of isolated rat basilar arteries (BA) in control, in the presence of inhibitors of vasomotor signaling pathways of know action and hemolysed blood. Methods and Results Vasomotor responses were measured by videomicroscopy and the intracellular Ca2+ by the Fura-2 AM ratiometric method. Under control conditions, nebivolol elicited a substantial dilation of the BA (from 216±22 to 394±20 μm; p<0.05) in a concentration-dependent manner (10−7 to 10−4 M). The dilatation was significantly reduced by endothelium denudation or by L-NAME (inhibitor of NO synthase) or by SQ22536 (adenylyl cyclase blocker). Dilatation of BA was also affected by beta-2 receptor blockade with butoxamine, but not by the guanylate cyclase blocker ODQ. Interestingly, beta-1 blockade by atenolol inhibited nebivolol-induced dilation. Also, the BKCa channel blocker iberiotoxin and KCa channel inhibitor TEA significantly reduced nebivolol-induced dilation. Nebivolol significantly reduced smooth muscle Ca2+ level, which correlated with the increases in diameters and moreover it reversed the hemolysed blood-induced constriction of BA. Conclusions Nebivolol seems to have an important dilator effect in cerebral arteries, which is mediated via several vasomotor mechanisms, converging on the reduction of smooth muscle Ca2+ levels. As such, nebivolol may be effective to improve cerebral circulation in various diseased conditions, such as hemorrhage.
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Affiliation(s)
- Peter Cseplo
- Institute for Translational Medicine and Szentagothai Research Centre, University of Pecs, Medical School, Pecs, Hungary.,Department of Central Anesthesiology and Intensive Therapy, Petz Aladar County Teaching Hospital, Gyor, Hungary
| | - Zoltan Vamos
- Institute for Translational Medicine and Szentagothai Research Centre, University of Pecs, Medical School, Pecs, Hungary.,Department of Anaesthesiology and Intensive Therapy, University of Pecs, Medical School, Pecs, Hungary
| | - Ivan Ivic
- Institute for Translational Medicine and Szentagothai Research Centre, University of Pecs, Medical School, Pecs, Hungary.,Department of Anatomy, University of Pecs, Medical School, Pecs, Hungary
| | - Orsolya Torok
- Institute for Translational Medicine and Szentagothai Research Centre, University of Pecs, Medical School, Pecs, Hungary
| | - Attila Toth
- Institute of Cardiology, Division of Clinical Physiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Akos Koller
- Institute for Translational Medicine and Szentagothai Research Centre, University of Pecs, Medical School, Pecs, Hungary.,Department of Neurosurgery, University of Pecs, Medical School, Pecs, Hungary.,Department of Physiology, New York Medical College, Valhalla, New York, United States of America.,Institute of Natural Sciences, University of Physical Education, Budapest, Hungary
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