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Rosenblum WI. Endothelium-dependent responses in the microcirculation observed in vivo. Acta Physiol (Oxf) 2018; 224:e13111. [PMID: 29873936 DOI: 10.1111/apha.13111] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2018] [Revised: 05/19/2018] [Accepted: 06/04/2018] [Indexed: 12/17/2022]
Abstract
Endothelium-dependent responses were first demonstrated 40 years ago in the aorta. Since then, extensive research has been conducted in vitro using conductance vessels and materials derived from them. However, the microcirculation controls blood flow to vital organs and has been the focus of in vivo studies of endothelium-dependent dilation beginning immediately after the first in vitro report. Initial in vivo studies employed a light/dye technique for selectively damaging the endothelium to unequivocally prove, in vivo, the existence of endothelium-dependent dilation and in the microvasculature. Endothelium-dependent constriction was similarly proven. Endothelium-dependent agonists include acetylcholine (ACh), bradykinin, arachidonic acid, calcium ionophore A-23187, calcitonin gene-related peptide (CGRP), serotonin, histamine and endothelin-1. Normal and disease states have been studied. Endothelial nitric oxide synthase, cyclooxygenase and cytochrome P450 have been shown to generate the mediators of the responses. Some of the key enzyme systems generate reactive oxygen species (ROS) like superoxide which may prevent EDR. However, one ROS, namely H2 O2 , is one of a number of hyperpolarizing factors that cause dilation initiated by endothelium. Depending upon microvascular bed, a single agonist may use different pathways to elicit an endothelium-dependent response. Interpretation of studies using inhibitors of eNOS is complicated by the fact that these inhibitors may also inhibit ATP-sensitive potassium channels. Other in vivo observations of brain arterioles failed to establish nitric oxide as the mediator of responses elicited by CGRP or by ACh and suggest that a nitrosothiol may be a better fit for the latter.
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Affiliation(s)
- W. I. Rosenblum
- Department of Pathology; Icahn School of Medicine at Mt Sinai NYC; New York NY USA
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Cseplo P, Vamos Z, Torok O, Ivic I, Toth A, Buki A, Koller A. Hemolyzed Blood Elicits a Calcium Antagonist and High CO 2 Reversible Constriction via Elevation of [Ca 2+] i in Isolated Cerebral Arteries. J Neurotrauma 2017; 34:529-534. [PMID: 27018759 DOI: 10.1089/neu.2015.4365] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
During acute subarachnoid hemorrhage, blood is hemolyzed, which is followed by a significant cerebrovascular spasm resulting in a serious clinical condition. Interestingly, however, the direct vasomotor effect of perivascular hemolyzed blood (HB) has not yet been characterized, preventing the assessment of contribution of vasoconstrictor mechanisms deriving from brain tissue and/or blood and development of possible treatments. We hypothesized that perivascular HB reduces the diameter of the cerebral arteries (i.e., basilar artery [BA]; middle cerebral artery [MCA]) by elevating vascular tissue [Ca2+]i level. Vasomotor responses were measured by videomicroscopy and intracellular Ca2+ by the Fura2-AM ratiometric method. Adding HB to the vessel chamber reduced the diameter significantly (BA: from 264 ± 7 to 164 ± 11 μm; MCA: from 185 ± 15 to 155 ± 14 μm), which was reversed to control level by wash-out of HB. Potassium chloride (KCl), HB, serum, hemolyzed red blood cell (RBC), plasma, and platelet suspension (PLTs) elicited significant constrictions of isolated basilar arteries. There was a significant increase in K+ concentration in hemolyzed HB (7.02 ± 0.22 mmol/L) compared to Krebs' solution (6.20 ± 0.01 mmol/L). Before HB, acetylcholine (ACh), sodium-nitroprussid (SNP), nifedipin, and CO2 elicited substantial dilations in cerebral arteries. In contrast, in the presence of HB dilations to ACh, SNP decreased, but not to nifedipine and CO2. After washout of HB, nitric oxide-mediated dilations remained significantly reduced compared to control. HB significantly increased the ratiometric Ca signal, which returned to control level after washout. In conclusion, perivascular hemolyzed blood elicits significant-nifedipine and high CO2 reversible-constrictions of isolated BAs and MCAs, primarily by increasing intracellular Ca2+, findings that can contribute to the refinement of local treatment of subarachnoid hemorrhage.
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Affiliation(s)
- Peter Cseplo
- 1 Institute of Translational Medicine, University of Pecs , Medical School, Pecs, Hungary .,2 Department of Central Anesthesiology and Intensive Therapy, Petz Aladar County Teaching Hospital , Gyor, Hungary .,6 Szentagothai Research Centre, University of Pecs , Pecs, Hungary
| | - Zoltan Vamos
- 3 Department of Anaesthesiology and Intensive Therapy, University of Pecs , Medical School, Pecs, Hungary
| | - Orsolya Torok
- 1 Institute of Translational Medicine, University of Pecs , Medical School, Pecs, Hungary
| | - Ivan Ivic
- 1 Institute of Translational Medicine, University of Pecs , Medical School, Pecs, Hungary
| | - Attila Toth
- 4 Institute of Cardiology, Division of Clinical Physiology, Faculty of Medicine, University of Debrecen , Debrecen, Hungary
| | - Andras Buki
- 5 Department of Neurosurgery, University of Pecs , Medical School, Pecs, Hungary .,6 Szentagothai Research Centre, University of Pecs , Pecs, Hungary .,7 MTA-PTE Clinical Neuroscience MR Research Group , Pecs, Hungary
| | - Akos Koller
- 1 Institute of Translational Medicine, University of Pecs , Medical School, Pecs, Hungary .,5 Department of Neurosurgery, University of Pecs , Medical School, Pecs, Hungary .,6 Szentagothai Research Centre, University of Pecs , Pecs, Hungary .,8 Institute of Natural Sciences, University of Physical Education , Budapest, Hungary .,9 Department of Physiology, New York Medical College , Valhalla, New York
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Watanabe Y, Littleton-Kearney MT, Traystman RJ, Hurn PD. Estrogen restores postischemic pial microvascular dilation. Am J Physiol Heart Circ Physiol 2001; 281:H155-60. [PMID: 11406480 DOI: 10.1152/ajpheart.2001.281.1.h155] [Citation(s) in RCA: 38] [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
Estrogen protects the brain from experimental cerebral ischemia, likely through both vascular and neuronal cellular mechanisms. The purpose of this study was to determine whether chronic estrogen treatment in males and repletion in ovariectomized (Ovx) females reverses abnormalities in pial arteriolar reactivity during reperfusion from global forebrain ischemia (4-vessel occlusion, 15 min) and whether the site of protection is vascular endothelium. Male and Ovx female rats were implanted with either placebo or a 25-microg 17 beta-estradiol pellet 10 days before ischemia. With the use of intravital microscopy, pial vessel dilation to ACh (10 microM) and S-nitroso-N-acetyl-penicillamine (SNAP; 1 microM) and vasoconstriction to serotonin (10 microM) was examined in situ at 30--60 min of reperfusion. Postischemic changes in vessel diameter were compared with preischemic values for each agent. Postischemic response to both ACh and SNAP was lost in males and Ovx females, but not in estrogen pellet-implanted males and estrogen-implanted Ovx females, suggesting that estrogen protects both endothelial and smooth muscle-mediated vasodilation. Ischemia blunted vessel constriction to serotonin regardless of treatment. These data demonstrate that estrogen acts as a vasoprotective agent within the cerebral circulation and can improve microvascular function under conditions of an acutely evolving ischemic pathology.
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Affiliation(s)
- Y Watanabe
- Department of Anesthesiology and Critical Care Medicine, Johns Hopkins Medical Institutions, Baltimore, Maryland 21287, USA
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Abstract
The vascular tone, vascular resistance and blood flow in the brain are regulated by neural and humoral factors in quite a different way from those of peripheral organs and tissues. In contrast to the dominant vasoconstrictor control in the periphery, the intracranial vascular tone is predominantly influenced by vasodilator mediators over vasoconstrictor ones. Recent studies have revealed that nitroxidergic vasodilator nerve and endothelium-derived hyperpolarizing factor (EDHF) or K+ channel opening substance appear to play important roles in the regulation of cerebral arterial and arteriolar tone in primate and subprimate mammals, in addition to the accepted information concerning the crucial contribution of endothelium-derived relaxing factor (EDRF) or nitric oxide (NO), polypeptides, prostanoids, etc. This article summarizes characteristic properties of vasodilator factors in controlling the cerebral arterial and arteriolar tone that undoubtedly contribute to circulatory homeostasis. The content includes vasodilator nerve, endogenous vasodilator substances, and vasodilator interventions such as hypoxia, hypercapnia and hyperosmolarity.
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Affiliation(s)
- N Toda
- Department of Pharmacology, Shiga University of Medical Science, Seta, Ohtsu, Japan
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Riedel MW, Anneser F, Haberl RL. Different mechanisms of L-arginine induced dilation of brain arterioles in normotensive and hypertensive rats. Brain Res 1995; 671:21-6. [PMID: 7537162 DOI: 10.1016/0006-8993(94)01292-p] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
We evaluated the response of pial arterioles to L-arginine in anesthetized normotensive rats and spontaneously hypertensive rats equipped with a closed cranial window. Topical application of 10(-6)-10(-4) mol/l L-arginine, which is known to be the endogenous substrate for the synthesis of nitric oxide, induced dose-dependent arteriolar vasodilation. The response was more pronounced in hypertensive than in normotensive rats (at the concentration of 10(-4) mol/l L-arginine: 18.3 +/- 3.3% vs. 6.7 +/- 1.7%, respectively, means +/- S.E.). The stereoisomer D-arginine had no effect in hypertensive rats. Topical application of the nitric oxide synthase inhibitor N-nitro-L-arginine converted L-arginine-induced dilation to constriction in normotensive and hypertensive rats. The cyclooxygenase inhibitor indomethacin (5 micrograms/ml cerebrospinal fluid) also blocked the dilation in both strains. Photochemical endothelial injury blocked L-arginine-induced dilation in normotensive rats, but only partly antagonized the response in hypertensive animals. Intravenous or topical pretreatment with the free radical scavenger superoxide dismutase significantly reduced the dilating response to 10(-4) mol/l L-arginine in hypertensive rats. Superoxide dismutase did not significantly change the response to L-arginine in normotensive animals. It is concluded that nitric oxid formation in the endothelium and liberation of cyclooxygenase products cause L-arginine-induced dilation in normotensive rats. While nitric oxide and cyclooxygenase products are also involved in L-arginine-induced dilation in spontaneously hypertensive rats, superoxide radicals contribute to the enhanced response in this strain. This mechanism appears to be specific for the hypertensive animals and is only partly dependent on an intact endothelium.
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Affiliation(s)
- M W Riedel
- Ludwig-Maximilians-Universität München, Klinikum Grosshadern, Germany
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Wu C, Chen S, Yen M. Attenuation of Endothelium-Dependent Relaxation in Mesenteric Artery during Noise-Induced Hypertension. J Biomed Sci 1994; 1:49-53. [PMID: 11725006 DOI: 10.1007/bf02258339] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
The present study was designed to determine whether there is a causal relationship between noise-induced hypertension and changes of endothelial function. Rats were exposed to noise stress (100 dB, 1 kHz, 4 h/day, 6 days/week) for 1-4 weeks. The systolic blood pressure was significantly increased after rats were exposed to noise stress for 3 weeks. The relaxant responses of isolated mesenteric arterial rings to endothelium-dependent vasodilators (A23187 and acetylcholine) in noise-treated rats were significantly less than those in control rats. This difference in response to acetylcholine still existed in the presence of methylene blue or N(omega)-nitro-L-arginine. On the other hand, the responses to the endothelium-dependent vasodilator nitroglycerin were not affected in rats exposed to noise stress. The attenuation to endothelium-dependent vasodilators during noise stress may result in increasing peripheral vascular resistance and thus elevate blood pressure. This indicates that noise-induced hypertension may be partly due to the alterations of endothelial activity. Copyright 1994 S. Karger AG, Basel
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Affiliation(s)
- C.C. Wu
- Department of Pharmacology, National Defense Medical Center, Taipei, Taiwan, ROC
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Abstract
1. The present study investigated the effects of noise stress (100 dB, 1 kHz, 4 h/day, 6 days/week) on both systolic blood pressure and vascular reactivities in rats exposed to noise for 2 and 4 weeks. The systolic blood pressure was significantly increased after rats were exposed to noise for 4 weeks but not 2 weeks. 2. In isolated thoracic aortic rings, the responses to serotonin were enhanced in noise-treated rats while there were no changes in response to phenylephrine and high K+ between noise-treated and control rats. 3. The relaxant responses to endothelium-dependent vasodilators (A23187 and acetylcholine) in noise-treated rats were less than those in control rats. The vasodilator responses to acetylcholine were completely abolished by methylene blue or N omega-nitro-L-arginine. 4. Responses to the endothelium-independent vasodilator, nitroglycerin, were not significantly changed after rats were exposed to noise. 5. The enhanced response to vasoconstrictors and the attenuation to endothelium-dependent vasodilators may account for elevations in blood pressure during noise stress. This indicates that the elevation in blood pressure by noise stress may be partly due to the deterioration of endothelial function.
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Affiliation(s)
- C C Wu
- Department of Pharmacology, National Defense Medical Center, Taipei, Taiwan
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Abstract
The products of univalent reduction of oxygen, superoxide anion radical, hydrogen peroxide, and the hydroxyl radical, are capable of causing cellular damage and death. They are, therefore, logical candidates as mediators of vascular and parenchymal injury in the central nervous system (CNS). This paper reviews the sources of oxygen radicals in the CNS, their effects on cerebral vessels and on brain and spinal cord parenchyma, and the evidence which implicates oxygen radicals in various pathological conditions of the CNS.
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Affiliation(s)
- H A Kontos
- Department of Medicine, Medical College of Virginia, Virginia Commonwealth University, Richmond 23298-0281
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