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Ostrowski RP, Colohan AR, Zhang JH. Molecular mechanisms of early brain injury after subarachnoid hemorrhage. Neurol Res 2006; 28:399-414. [PMID: 16759443 DOI: 10.1179/016164106x115008] [Citation(s) in RCA: 204] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
OBJECTIVES Increasing body of experimental and clinical data indicates that early brain injury after initial bleeding largely contributes to unfavorable outcome after subarachnoid hemorrhage (SAH). This review presents molecular mechanisms underlying brain injury at its early stages after SAH. METHODS PubMed was searched using term 'subarachnoid hemorrhage' and key words referring to molecular and cellular pathomechanisms of SAH-induced early brain injury. RESULTS The authors reviewed intracranial phenomena and molecular agents that contribute to the early development of pathological sequelae of SAH in cerebral and vascular tissues, including cerebral ischemia and its interactions with injurious blood components, blood-brain barrier disruption, brain edema and apoptosis. DISCUSSION It is believed that detailed knowledge of molecular signaling pathways after SAH will serve to improve therapeutic interventions. The most promising approach is the protection of neurovascular unit including anti-apoptosis therapy.
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del Valle-Rodríguez A, Calderón E, Ruiz M, Ordoñez A, López-Barneo J, Ureña J. Metabotropic Ca(2+) channel-induced Ca(2+) release and ATP-dependent facilitation of arterial myocyte contraction. Proc Natl Acad Sci U S A 2006; 103:4316-21. [PMID: 16537528 PMCID: PMC1449690 DOI: 10.1073/pnas.0508781103] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Voltage-gated Ca(2+) channels in arterial myocytes can mediate Ca(2+) release from the sarcoplasmic reticulum and, thus, induce contraction without the need of extracellular Ca(2+) influx. This metabotropic action of Ca(2+) channels (denoted as calcium-channel-induced calcium release or CCICR) involves activation of G proteins and the phospholipase C-inositol 1,4,5-trisphosphate pathway. Here, we show a form of vascular tone regulation by extracellular ATP that depends on the modulation of CCICR. In isolated arterial myocytes, ATP produced facilitation of Ca(2+)-channel activation and, subsequently, a strong potentiation of CCICR. The facilitation of L-type channel still occurred after full blockade of purinergic receptors and inhibition of G proteins with GDPbetaS, thus suggesting that ATP directly interacts with Ca(2+) channels. The effects of ATP appear to be highly selective, because they were not mimicked by other nucleotides (ADP or UTP) or vasoactive agents, such as norepinephrine, acetylcholine, or endothelin-1. We have also shown that CCICR can trigger arterial cerebral vasoconstriction in the absence of extracellular calcium and that this phenomenon is greatly facilitated by extracellular ATP. Although, at low concentrations, ATP does not induce arterial contraction per se, this agent markedly potentiates contractility of partially depolarized or primed arteries. Hence, the metabotropic action of L-type Ca(2+) channels could have a high impact on vascular pathophysiology, because, even in the absence of Ca(2+) channel opening, it might mediate elevations of cytosolic Ca(2+) and contraction in partially depolarized vascular smooth muscle cells exposed to small concentrations of agonists.
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Affiliation(s)
| | - Eva Calderón
- Unidad de Cirugía Cardiovascular, Hospital Universitario Virgen del Rocío, Universidad de Sevilla, E-41013, Seville, Spain
| | - Myriam Ruiz
- Unidad de Cirugía Cardiovascular, Hospital Universitario Virgen del Rocío, Universidad de Sevilla, E-41013, Seville, Spain
| | - Antonio Ordoñez
- Unidad de Cirugía Cardiovascular, Hospital Universitario Virgen del Rocío, Universidad de Sevilla, E-41013, Seville, Spain
| | | | - Juan Ureña
- *Laboratorio de Investigaciones Biomédicas and
- To whom correspondence should be addressed at:
Laboratorio de Investigaciones Biomédicas, Edificio de Laboratorios, 2nd Planta, Hospital Universitario Virgen del Rocío, Avenida Manuel Siurot s/n, E-41013, Seville, Spain. E-mail:
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Macdonald RL, Weir B, Zhang J, Marton LS, Sajdak M, Johns LM. Adenosine triphosphate and hemoglobin in vasospastic monkeys. Neurosurg Focus 2004; 3:e3. [PMID: 15104409 DOI: 10.3171/foc.1997.3.4.6] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Adenosine triphosphate (ATP) is a vasoactive compound found in high levels inside erythrocytes that may contribute to vasospasm occurring after subarachnoid hemorrhage (SAH). This study was instituted to test whether ATP causes vasospasm in a monkey model. Thirty-two monkeys were randomized to four groups of eight monkeys each to undergo cerebral angiography at baseline (Day 0) and then at Day 7 after subarachnoid placement of: 1) agarose, 2) ATP in agarose, 3) autologous hemolysate in agarose, or 4) purified human hemoglobin A(0) in agarose. Vasospasm was assessed by comparison of Day 0 and Day 7 angiograms between and within groups and by pathological examination of a subset of perfusion-fixed monkeys. Levels of adenine nucleotides were measured on Day 7 in subarachnoid agarose by high-pressure liquid chromatography. There was significant vasospasm of the right middle cerebral artery in groups given ATP (-28 +/- 7% reduction, paired t-test, p < 0.05), hemolysate (-23 +/- 7%, p < 0.05), or pure hemoglobin (-15 +/- 2%, p < 0.005). Analysis of variance revealed no significant differences between groups in diameters of cerebral arteries on Day 7. Pathological examination showed mild inflammation in the subarachnoid spaces of animals exposed to hemolysate or hemoglobin and less inflammation in those given ATP or agarose. There were no pathological changes in the cerebral arteries of animals in any group. Most of the ATP diffused out of the subarachnoid agarose by Day 7, and levels of adenine nucleotides in subarachnoid agarose were higher on Day 7 in animals exposed to hemoglobin or hemolysate. It is concluded that ATP could contribute to vasospasm occurring after SAH but that further investigations are necessary to determine if levels of ATP adjacent to vasospastic arteries are sufficient to contribute to vasospasm. In addition, no observation was made of severe vasospasm with histopathological changes in the arteries equivalent to that produced by whole blood clot in the subarachnoid space of monkeys. It should be determined whether this is because a single compound, such as ATP or hemoglobin, causes vasospasm, but that placing the compound in agarose alters its delivery and decreases the amount of vasospasm produced, or whether vasospasm is a more complex, multifactorial process.
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Affiliation(s)
- R L Macdonald
- Section of Neurosurgery, University of Chicago Medical Center, Chicago, Illinois 60637, USA.
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Miyagi Y, Zhang JH. Aalpha,beta-methylene ATP enhances P2Y4 contraction of rabbit basilar artery. Am J Physiol Heart Circ Physiol 2004; 286:H1546-51. [PMID: 15020308 DOI: 10.1152/ajpheart.00926.2003] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Interactions between different selective P2 receptor agonists have been used as tools to identify different P2 receptor subtypes. In the present study, we examined the P2 receptor subtypes and the mechanisms of potentiation of UTP contraction (P2Y contraction) by alpha,beta-methylene ATP [(2-carboxypiperazin-4-yl)propyl-1-phosphanoic acid (CPP), a P2X agonist] using isometric tension in the denuded rabbit basilar artery. We made the following observations: 1). a predominant P2X receptor contraction was observed in the rabbit ear artery by the rank order of CPP >> 2-methylthioATP > ATP > UTP; 2). functional P2Y receptors were observed in the rabbit basilar artery by the rank order of UTP >> ATP = CPP = 2-methylthioATP; 3). CPP potentiated UTP-, ATP-, and ATPgammaS-induced contractions, possibly by activation of P2Y4 receptors because ATPgammaS does not activate P2Y6 receptors; and 4). ectonucleotidase did not play a predominant role in the potentiative effect of CPP because Evans blue, Ca(2+)-free medium, or divalent cation Ni(2+) did not affect the effect of CPP. Evans blue potentiated the contraction by UTP but not by ATP or ATPgammaS. We conclude that CPP enhanced P2Y4-mediated contraction in the rabbit basilar artery, and the influence by ectonucleotidases on CPP-potentiation remains unclear.
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Affiliation(s)
- Yasushi Miyagi
- Department of Neurosurgery, University of Mississippi Medical Center, Jackson, Mississippi, USA
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5
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Malmsjö M, Hou M, Pendergast W, Erlinge D, Edvinsson L. Potent P2Y6 receptor mediated contractions in human cerebral arteries. BMC Pharmacol 2003; 3:4. [PMID: 12737633 PMCID: PMC156657 DOI: 10.1186/1471-2210-3-4] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2003] [Accepted: 05/09/2003] [Indexed: 11/13/2022] Open
Abstract
BACKGROUND Extracellular nucleotides play an important role in the regulation of vascular tone and may be involved in cerebral vasospasm after subarachnoidal haemorrhage. This study was designed to characterise the contractile P2 receptors in endothelium-denuded human cerebral and omental arteries. The isometric tension of isolated vessel segments was recorded in vitro. P2 receptor mRNA expression was examined by RT-PCR. RESULTS In human cerebral arteries, the selective P2Y6 receptor agonist, UDPbetaS was the most potent of all the agonists tested (pEC50 = 6.8 PlusMinus; 0.7). The agonist potency; UDPbetaS > alphabeta-MeATP > UTPgammaS > ATPgammaS > ADPbetaS = 0, indicated the presence of contractile P2X1 P2Y2, P2Y4 and P2Y6, but not P2Y1 receptors, in human cerebral arteries. In human omental arteries, UDPbetaS was inactive. The agonist potency; alphabeta-MeATP > ATPgammaS = UTPgammaS > ADPbetaS = UDPbetaS = 0, indicated the presence of contractile P2X1, and P2Y2 receptors, but not P2Y1 or P2Y6 receptors, in human omental arteries. RT-PCR analysis of endothelium-denuded human cerebral and omental arteries demonstrated P2X1, P2Y1, P2Y2 and P2Y6 receptor mRNA expression. There were no bands for the P2Y4 receptor mRNA in the omental arteries, while barely detectable in the cerebral arteries. CONCLUSIONS P2Y6 receptors play a prominent role in mediating contraction of human cerebral arteries. Conversely, no such effect can be observed in human omental arteries and previous results confirm the absence of P2Y6 receptors in human coronary arteries. The P2Y6 receptor might be a suitable target for the treatment of cerebral vasospasm.
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Affiliation(s)
- Malin Malmsjö
- Division of Experimental Vascular Research, Department of Internal Medicine, Lund University Hospital, Lund, Sweden
| | - Mingyan Hou
- Division of Experimental Vascular Research, Department of Internal Medicine, Lund University Hospital, Lund, Sweden
| | | | - David Erlinge
- Department of Cardiology, Lund University Hospital, Lund, Sweden
| | - Lars Edvinsson
- Division of Experimental Vascular Research, Department of Internal Medicine, Lund University Hospital, Lund, Sweden
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Malmsjö M, Hou M, Pendergast W, Erlinge D, Edvinsson L. The stable pyrimidines UDPbetaS and UTPgammaS discriminate between contractile cerebrovascular P2 receptors. Eur J Pharmacol 2003; 458:305-11. [PMID: 12504787 DOI: 10.1016/s0014-2999(02)02787-5] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Extracellular nucleotides were used to characterise the contractile P2 receptors in the rat basilar artery. The isometric tension was recorded in vitro and receptor mRNA expression was examined by reverse transcriptase polymerase chain reaction (RT-PCR) after endothelium-denudation. Transient vasoconstriction was evoked by alphabeta-methylene-adenosine triphosphate (alphabeta-MeATP), indicating the presence of P2X(1) receptors. The P2Y receptors were analysed after P2X receptor desensitisation with 10 microM alphabeta-MeATP. Uridine diphosphate (UDP) and uridine triphosphate (UTP) induced sustained contractions of similar magnitude. The stable nucleotide analogue, uridine 5'-O-thiodiphosphate (UDPbetaS), was clearly more potent than uridine 5'-O-3-thiotriphosphate (UTPgammaS), suggesting prominent contractile effects of P2Y(6) receptors. P2Y(2) and P2Y(4) receptors might also be involved in nucleotide responses, since UTPgammaS and adenosine 5'-O-3-thiotriphosphate (ATPgammaS) were of similar potency. The P2Y(1) selective agonists, adenosine 5'-O-thiodiphosphate (ADPbetaS) and 2-methylthioadenosine diphosphate (2-MeSADP) did not induce contractions. RT-PCR analysis demonstrated P2X(1), P2Y(1), P2Y(2) and P2Y(6) receptor mRNA expression, while the P2Y(4) band was weak. In conclusion, extracellular nucleotides induce contractions of cerebral arteries primarily by activation of P2Y(6) receptors on smooth muscle cells, with a lesser contribution of P2Y(2) and P2X(1) receptors. Although mRNA for the P2Y(1) receptor was detected by RT-PCR, it does not mediate contraction.
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Affiliation(s)
- Malin Malmsjö
- Division of Experimental Vascular Research, Department of Internal Medicine, Lund University Hospital, Lund, Sweden.
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7
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Abstract
Cerebral vasospasm is a deadly complication following the rupture of intracranial aneurysms. The time course of cerebral vasospasm is unique in that it is slow developing, usually takes 4-7 days to peak, but lasts up to 2-3 weeks, and is resistant to most known vasodilators. These special features make cerebral vasospasm the most important determinant in the outcome of patients suffering subarachnoid hemorrhage. The available treatment strategies include mechanical dilation of spastic cerebral arteries (angioplasty) and non-selective vasodilatation such as by Ca(2+) channel blockers. One new development in the experimental treatment of cerebral vasospasm is the looming target of signaling pathways. Understanding vasospastic signals in cerebral arteries might offer a new avenue for selective treatment of cerebral vasospasm in the future.
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Affiliation(s)
- Alexander Y. Zubkov
- Department of Neurology, University of Mississippi Medical Center, Jackson, MS, USA
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Yin W, Tibbs R, Tang J, Badr A, Zhang J. Haemoglobin and ATP levels in CSF from a dog model of vasospasm. J Clin Neurosci 2002; 9:425-8. [PMID: 12217672 DOI: 10.1054/jocn.2001.0968] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Haemoglobin and adenosine 5'-triposphate (ATP) released from lysed erythrocytes have been postulated to be responsible for delayed cerebral vasospasm after subarachnoid haemorrhage (SAH). However, the concentrations of haemoglobin and ATP in cerebrospinal fluid (CSF) in patients or in an animal model of vasospasm have not been reported. In this study, 12 mongrel dogs underwent a double blood injection via the cisterna magna on day 0 and 2, after an initial collection of CSF. On day 3, 5 or 7, the dogs were sacrificed after a second collection of CSF. An angiogram was recorded on day 0 and on the day of sacrifice. Results showed that the diameter of the dog's basilar artery was reduced 20% on day 3 (P > 0.05), 35% on day 5 (P < 0.05) and 45% on day 7 (P < 0.05). The concentrations of OxyHb, deOxyHb and MetHb in CSF were increased (P < 0.05), and all peaked on day 3. OxyHb and MetHb remained significantly higher than control (day 0) from day 3 to day 7, while deOxyHb remained at a high level on day 5 but returned to normal on day 7. In contrast, ATP was decreased (P < 0.05) on days 5 and 7 after SAH compared with day 0. The results indicate that haemoglobin might be involved in the development of cerebral vasospasm. The possible role of ATP in vasospasm remains unclear.
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Affiliation(s)
- W Yin
- Department of Neurosurgery, University of Mississippi Medical center, Jackson, MS 39216, USA
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9
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Kimura H, Meguro T, Badr A, Zhang JH. Suramin-induced reversal of chronic cerebral vasospasm in experimental subarachnoid hemorrhage. J Neurosurg 2002; 97:129-35. [PMID: 12134903 DOI: 10.3171/jns.2002.97.1.0129] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
OBJECT The naphthylsulfonate derivative suramin is an inhibitor of growth factor receptors (receptor tyrosine kinases) and G protein-coupled P2Y receptors. Both types of these receptors are suspected of being involved in cerebral vasospasm after subarachnoid hemorrhage (SAH). In the current study, the authors examined the therapeutic effects of suramin and a selective P2X-receptor antagonist, pyridoxalphosphate-6-azophenyl-2',4'-disulfonic acid (PPADS), in the reversal of vasospasm in an established canine double-hemorrhage model. METHODS Twenty-four dogs underwent double blood injection into the cisterna magna, with injections given on Days 0 and 2. The dogs were divided randomly into three groups (six animals in each group) to be treated from Days 2 through 6 with the vehicle dimethyl sulfoxide, suramin, or PPADS. An additional group of six dogs received double blood injection without any treatment and served as an SAH control group. The animals were killed on Day 7. Angiography was performed on Day 0 before blood injection and again on Day 7 before the animals were killed. After the death of the animals, the basilar arteries (BAs) were collected for morphological studies and determination of tyrosine kinase expression, and the bloody cerebrospinal fluid (CSF) produced by the hemorrhages was collected for measurement of oxyhemoglobin and adenosine triphosphate (ATP). In the SAH control group, the mean diameter of the BAs on Day 7 was 46.23 +/- 6.32% of the value on Day 0 (which served as a reference of 100%). In the DMSO-treated group, the mean residual diameter of the BA was 47.77 +/- 0.8% on Day 7 compared with the value on Day 0. Suramin, but not PPADS, increased the residual diameter to 74.02 +/- 4.24% on Day 7. On Day 7 the level of ATP in the CSF was decreased and the level of oxyhemoglobin was increased, compared with values measured on Day 0. Suramin, but not PPADS, reduced tyrosine phosphorylation in the spastic BAs. CONCLUSIONS By reducing tyrosine kinase activity, suramin may be useful in the treatment of cerebral vasospasm.
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Affiliation(s)
- Hitoshi Kimura
- Department of Neurosurgery, University of Mississippi Medical Center, Jackson, USA
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10
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Miao LY, Tang JP, Esposito DP, Zhang JH. Age-related changes in P2 receptor mRNA of rat cerebral arteries. Exp Gerontol 2001; 37:67-79. [PMID: 11738148 DOI: 10.1016/s0531-5565(01)00159-0] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Aging alters the vascular response to extracellular nucleotides. However, the molecular mechanisms that underlie the effect of aging remain unclear. We investigated the mRNA expression of P2X(1), P2Y(1), P2Y(2) subtypes of the nucleotide receptors (P2) in the basilar artery, aorta and carotid artery from male Sprague-Dawley rats, 2-months and 19-months old. In the basilar arteries of 19-month old rats, as compared to the 2-month old rats, the P2X(1) receptor transcripts were reduced and the P2Y(1) and P2Y(2) receptor mRNA was increased. In the aorta and carotid arteries, P2Y(1) receptor mRNA was decreased in the 19-month old rats when compared to the 2-month old rats. There were no marked changes of P2X(1) and P2Y(2) receptor mRNA between the two age groups in the aorta or carotid artery. In endothelial cells, P2Y(1) and P2Y(2) receptor mRNA was reduced with age. We concluded that, down-regulation of P2X(1) and up-regulation of P2Y(1), P2Y(2) receptor mRNA in smooth muscle cells and down-regulation of P2Y(1) and P2Y(2) receptor mRNA on vascular endothelial cells might underlie the changes of cerebral vascular tone in aging.
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Affiliation(s)
- L Y Miao
- Department of Neurosurgery, University of Mississippi Medical Center, 2500 North State Street, Jackson, MS 39216-4505, USA
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11
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Patlolla A, Ogihara K, Zubkov A, Aoki K, Parent AD, Zhang JH. Role of tyrosine kinase in fibroblast compaction and cerebral vasospasm. ACTA NEUROCHIRURGICA. SUPPLEMENT 2001; 76:227-30. [PMID: 11450013 DOI: 10.1007/978-3-7091-6346-7_46] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/20/2023]
Abstract
Hemolysate, a proposed causative agent for cerebral vasospasm following subarachnoid hemorrhage, produces contraction of cerebral arteries by activation of tyrosine kinases. In addition, hemolysate accelerates fibroblast collagen compaction that could play a role in cerebral vasospasm. We studied the effect of hemolysate on tyrosine phosphorylation and fibroblast collagen compaction in cultured dog cerebral and human dermal fibroblasts using tyrosine kinase inhibitors and tyrosine antibodies (Western blot). 1) Hemolysate was found to enhance tyrosine phosphorylation of two proteins approximately 64 and 120 kDa. The effect of hemolysate was time- and concentration-dependent. 2) Two main components in hemolysate, oxyhemoglobin and adenosine triphosphate (ATP), produced similar results to that of hemolysate. 3) Tyrosine kinase inhibitor genistein and tyrphostin A51 (30 microM) markedly reduced the effect of hemolysate on tyrosine phosphorylation. 4) In another study, hemolysate increased fibroblast collagen compaction and the effect of hemolysate was reduced by genistein and tyrphostin A51. We conclude that hemolysate activates tyrosine kinase that may lead to acceleration of fibroblast compaction. This effect of hemolysate may contribute to cerebral vasospasm.
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Affiliation(s)
- A Patlolla
- Department of Neurosurgery, University of Mississippi Medical Center, Jackson, Mississippi, USA
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12
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Abstract
We sought to define the basic mechanisms by which pyrimidine nucleotides constrict rat coronary resistance arteries. Uridine triphosphate (UTP) caused a dose-dependent constriction in coronary arteries stripped of endothelium. UTP also depolarized and increased cytosolic Ca2+ in coronary smooth muscle cells. Nisoldipine, an antagonist of voltage-operated Ca2+ channels, blocked the rise in cytosolic Ca2+ and reduced UTP-induced vasoconstriction by approximately 75% which suggests a prominent role for depolarization in this constrictor response. The ionic basis of UTP-induced depolarization was subsequently explored in coronary smooth muscle cells using whole-cell patch-clamp electrophysiology. In the absence of K+ and with CsCl in the pipette, UTP (40 microM) activated a sustained inwardly rectifying current (-0.66 +/- 0.10 pA/pF at -60 mV). A 100 mM reduction in bath Na+ shifted the reversal potential of this current (from -2 +/- 1 to -28 +/- 4 mV) and reduced the magnitude (from -2.26 +/- 0.61 to -0.51 +/- 0.11 pA/pF). In addition to activating a depolarizing cation current, UTP inhibited hyperpolarizing outward currents. Specifically, UTP inhibited ATP-sensitive and voltage-dependent K+ currents yet had no effect on inwardly rectifying and Ca2+-activated K+ channels. This study indicates that electromechanical coupling is integral to pyrimidine-induced constriction in coronary resistance arteries.
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MESH Headings
- Animals
- Arteries/drug effects
- Arteries/metabolism
- Calcium/metabolism
- Calcium Channel Blockers/pharmacology
- Cells, Cultured
- Coronary Vessels/drug effects
- Coronary Vessels/metabolism
- Cytosol/metabolism
- Dose-Response Relationship, Drug
- Female
- In Vitro Techniques
- Ion Channels/drug effects
- Ion Channels/physiology
- Membrane Potentials/drug effects
- Membrane Potentials/physiology
- Muscle, Smooth, Vascular/cytology
- Muscle, Smooth, Vascular/drug effects
- Muscle, Smooth, Vascular/metabolism
- Nisoldipine/pharmacology
- Patch-Clamp Techniques
- Potassium Channel Blockers
- Potassium Channels/metabolism
- RNA, Messenger/metabolism
- Rats
- Rats, Sprague-Dawley
- Receptors, Purinergic P2/genetics
- Receptors, Purinergic P2/metabolism
- Uridine Triphosphate/metabolism
- Uridine Triphosphate/pharmacology
- Vasoconstriction/drug effects
- Vasoconstriction/physiology
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Affiliation(s)
- D G Welsh
- Department of Pharmacology, University of Vermont, Burlington, Vermont 05405, USA
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Macdonald RL, Weir BK, Marton LS, Zhang ZD, Sajdak M, Johns LM, Kowalczuk A, Borsody M. Role of adenosine 5'-triphosphate in vasospasm after subarachnoid hemorrhage: human investigations. Neurosurgery 2001; 48:854-62; discussion 862-3. [PMID: 11322446 DOI: 10.1097/00006123-200104000-00033] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
OBJECTIVE Adenosine 5'-triphosphate (ATP) is a vasoactive compound found in high concentrations inside erythrocytes. This compound may contribute to vasospasm after subarachnoid hemorrhage (SAH). We assessed the hypothesis that ATP contributes to vasospasm in humans. METHODS ATP and hemoglobin concentrations were measured in cerebrospinal fluid (CSF) from humans with SAH and in blood incubated in vitro. The vasoactivity of the human CSF samples and of fractionated (fractions with molecular weight greater than or less than 10 kDa) and unfractionated blood incubated in vitro was assessed by application of samples to canine basilar artery segments under isometric tension. RESULTS ATP in human CSF declined within 72 hours of SAH to concentrations too low to contract cerebral arteries. Vasoactivity of human CSF correlated with the concentration of hemoglobin. The vasoactivity of incubated erythrocyte hemolysates remained high despite a decline in ATP concentrations. Fractionation of incubated erythrocyte hemolysates showed that for incubation periods up to 7 days, all vasoactivity was in a fraction of molecular weight greater than 10 kDa. CONCLUSION ATP is unlikely to contribute to vasospasm because the concentrations in CSF after SAH in humans are not high enough to cause vasospasm after 72 hours. The vasoactivity of erythrocyte hemolysate is not related to the ATP or ferrous hemoglobin content but may be related to the total hemoglobin content. Therefore, ATP is unlikely to be a major cause of clinically significant delayed vasospasm.
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Affiliation(s)
- R L Macdonald
- Section of Neurosurgery, University of Chicago Medical Center, Pritzker School of Medicine, Illinois, USA.
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Macdonald RL, Weir BK, Marton LS, Zhang ZD, Sajdak M, Johns LM, Kowalczuk A, Borsody M. Role of Adenosine 5′-Triphosphate in Vasospasm after Subarachnoid Hemorrhage: Human Investigations. Neurosurgery 2001. [DOI: 10.1227/00006123-200104000-00033] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
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Carpenter RC, Miao L, Miyagi Y, Bengten E, Zhang JH. Altered expression of P(2) receptor mRNAs in the basilar artery in a rat double hemorrhage model. Stroke 2001; 32:516-22. [PMID: 11157191 DOI: 10.1161/01.str.32.2.516] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND AND PURPOSE Extracellular ATP might induce cerebral vasospasm after subarachnoid hemorrhage through P(2) receptor. To investigate the roles of P(2) receptor subtypes in vasospasm, we examined the changes in mRNA expression of P(2) receptor subtypes in basilar arteries from double cisternal blood injection rat models. METHODS One hundred male Sprague-Dawley rats, each weighing 350 to 400 g, were divided into 2 groups of 50. In the first group (n=50), the autologous arterial blood (0.2 to 0.3 mL) was injected into the cisterna magna on days 0 and 2. The rats were killed on day 3, 5, or 7 (n=10 in each group). In the sham group (n=10), the rats were injected with saline (0.3 mL) instead of blood. Ten rats were killed without blood or saline injection and served as control. The basilar arteries from rats in each group were used for reverse transcription and polymerase chain reaction. In another group of 50 rats, the same experiment was conducted, and the basilar arteries were collected for transmission electron microscopic study. RESULTS In the subarachnoid hemorrhage groups, transmission electron microscopy showed the reduction in vessel perimeter on days 5 and 7 to be approximately 30% to 40%. The P(2X1) mRNA level was significantly decreased on day 3 and recovered on days 5 and 7. The P(2Y1) mRNA level was transiently increased on day 5, and the P(2Y2) mRNA level was elevated from day 5 to day 7 (P:<0.05). CONCLUSIONS The differential expression of the P(2) receptors indicates that P(2X1) subtype might not play an important role in vasospasm. The upregulation of P(2Y1) and P(2Y2) receptors might enable ATP to produce contraction at low levels of concentration.
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MESH Headings
- Animals
- Basilar Artery/metabolism
- Basilar Artery/pathology
- Basilar Artery/ultrastructure
- Brain/blood supply
- Brain/pathology
- Cisterna Magna
- Disease Models, Animal
- Glyceraldehyde-3-Phosphate Dehydrogenases/genetics
- Glyceraldehyde-3-Phosphate Dehydrogenases/metabolism
- Image Processing, Computer-Assisted
- Male
- Microscopy, Electron
- Muscle, Smooth, Vascular/pathology
- Muscle, Smooth, Vascular/ultrastructure
- RNA, Messenger/metabolism
- Rats
- Rats, Sprague-Dawley
- Receptors, Purinergic P2/genetics
- Receptors, Purinergic P2/metabolism
- Reverse Transcriptase Polymerase Chain Reaction
- Subarachnoid Hemorrhage/metabolism
- Subarachnoid Hemorrhage/pathology
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Affiliation(s)
- R C Carpenter
- Department of Neurosurgery, University of Mississippi MedicalCenter, 2500 N State St, Jackson, MS 39216, USA
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16
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Zubkov AY, Rollins KS, McGehee B, Parent AD, Zhang JH. Relaxant effect of U0126 in hemolysate-, oxyhemoglobin-, and bloody cerebrospinal fluid-induced contraction in rabbit basilar artery. Stroke 2001; 32:154-61. [PMID: 11136931 DOI: 10.1161/01.str.32.1.154] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND AND PURPOSE It has been suggested that mitogen-activated protein kinase (MAPK) is involved in cerebral vasospasm after subarachnoid hemorrhage. The present study was undertaken to explore the inhibitory effect of U0126, a novel MAPK inhibitor, in the contraction of the rabbit basilar artery by 3 spasmogens: hemolysate, oxyhemoglobin, and bloody cerebrospinal fluid (CSF) from patients with vasospasm. METHODS The contraction and relaxation of rabbit basilar arteries were measured by isometric tension. MAPK immunoprecipitation was assessed by Western blot analysis. RESULTS (1) Pretreatment of the rabbit basilar arteries with U0126 reduced contractions to hemolysate, oxyhemoglobin, or bloody CSF applied subsequently. (2) In the absence of endothelial cells, U0126 produced an inhibitory effect similar to the contractions induced by hemolysate, oxyhemoglobin, or bloody CSF. (3) U0126 relaxed the sustained contraction induced by hemolysate, oxyhemoglobin, or bloody CSF. (4) Hemolysate, oxyhemoglobin, and bloody CSF enhanced MAPK immunoprecipitation. (5) U0126 reduced MAPK immunoprecipitation induced by hemolysate, oxyhemoglobin, and bloody CSF. (6) Hemolysate, oxyhemoglobin, and bloody CSF significantly increased MAPK activity in the rabbit basilar artery. (7) U0126 abolished the effect of hemolysate, oxyhemoglobin, or bloody CSF on MAPK activation. CONCLUSIONS This study demonstrated a role of MAPK in the contraction of rabbit basilar arteries by hemolysate, oxyhemoglobin, and bloody CSF. MAPK inhibitor U0126 may be useful in the treatment of cerebral vasospasm.
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Affiliation(s)
- A Y Zubkov
- Department of Neurosurgery, University of Mississippi Medical Center, Jackson, MS 39216-4505, USA
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17
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Aoki K, Zubkov AY, Parent AD, Zhang JH. Mechanism of ATP-induced [Ca(2+)](i) mobilization in rat basilar smooth muscle cells. Stroke 2000; 31:1377-84; discussion 1384-5. [PMID: 10835460 DOI: 10.1161/01.str.31.6.1377] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND AND PURPOSE We have previously reported that extracellular ATP activates P(2u) receptors and increases intracellular free Ca(2+) ([Ca(2+)](i)) by G protein/phospholipase C/inositol 1,4,5-triphosphate pathways in cerebral artery smooth muscle cells. However, the possible contribution of other signaling pathways remains unclear. This study was undertaken to investigate the role of protein tyrosine kinase (PTK) and mitogen-activated protein kinase (MAPK) in mediating ATP-induced Ca(2+) mobilization in rat basilar artery smooth muscle cells (RBASMCs). METHODS RBASMCs were freshly isolated, and [Ca(2+)](i) was monitored by fura 2 microfluorimetry. MAPK phosphorylation was studied by the Western blot technique. RESULTS ATP produced a biphasic [Ca(2+)](i) response, which consists of releasing Ca(2+) from internal stores and influx from extracellular space. PTK inhibitors tyrphostin 51 and genistein inhibited [Ca(2+)](i) response to ATP. Tyrphostin A1, an inactive analogue of tyrphostins, failed to reduce the ATP-induced response. MAPK kinase inhibitor PD98059, but not U0126, reduced the ATP-induced [Ca(2+)](i) response. Phosphatidylinositol 3-kinase (PI3-K) tyrosine kinase inhibitor wortmannin, but not janus tyrosine kinase (JAK2) inhibitor AG490, partially inhibited the [Ca(2+)](i) response induced by ATP. In addition, ATP enhanced MAPK phosphorylation in a concentration- and time-dependent manner, and genistein, tyrphostin 51, PD98059, and U0126 inhibited MAPK phosphorylation. CONCLUSIONS Extracellular ATP produced [Ca(2+)](i) elevation and MAPK phosphorylation in RBASMCs, and the effect was regulated by PTK. The role of MAPK in ATP-induced [Ca(2+)](i) elevation is not clear. PI3-K tyrosine kinase and JAK2 tyrosine kinase may not play an important role in the ATP-induced [Ca(2+)](i) response in RBASMCs.
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MESH Headings
- Adenosine Triphosphate/physiology
- Animals
- Basilar Artery/cytology
- Blotting, Western
- Calcium Signaling/physiology
- Cells, Cultured
- Enzyme Inhibitors/pharmacology
- Extracellular Space/chemistry
- Female
- Fluorometry
- Intracellular Fluid/chemistry
- Janus Kinase 2
- MAP Kinase Signaling System/drug effects
- Microchemistry
- Mitogen-Activated Protein Kinases/antagonists & inhibitors
- Mitogen-Activated Protein Kinases/physiology
- Muscle, Smooth, Vascular/cytology
- Muscle, Smooth, Vascular/drug effects
- Muscle, Smooth, Vascular/metabolism
- Phosphatidylinositol 3-Kinases/physiology
- Phosphoinositide-3 Kinase Inhibitors
- Phosphorylation/drug effects
- Protein Processing, Post-Translational/drug effects
- Protein-Tyrosine Kinases/antagonists & inhibitors
- Protein-Tyrosine Kinases/physiology
- Proto-Oncogene Proteins
- Rats
- Rats, Sprague-Dawley
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Affiliation(s)
- K Aoki
- Department of Neurosurgery, University of Mississippi Medical Center, Jackson 39216-4505, USA
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18
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Abstract
The mechanisms responsible for subarachnoid hemorrhage (SAH)-induced vasospasm are under intense investigation but remain incompletely understood. A consequence of SAH-induced vasospasm, cerebral infarction, produces a nonrecoverable ischemic tissue core surrounded by a potentially amenable penumbra. However, successful treatment has been inconsistent. In this review, we summarize the basic molecular biology of cerebrovascular regulation, describe recent developments in molecular biology to elucidate the mechanisms of SAH-induced vasospasm, and discuss the potential contribution of cerebral microcirculation regulation to the control of ischemia. Our understanding of the pathogenesis of SAH-induced vasospasm remains a major scientific challenge; however, molecular biological techniques are beginning to uncover the intracellular mechanisms involved in vascular regulation and its failure. Recent findings of microvascular regulatory mechanisms and their failure after SAH suggest a role in the development and size of the ischemia. Progress is being made in identifying the various components in the blood that cause SAH-induced vasospasm. Thus, our evolving understanding of the underlying molecular mechanism may provide the basis for improved treatment after SAH-induced vasospasm, especially at the level of the microcirculation.
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Affiliation(s)
- H H Dietrich
- Department of Neurological Surgery, Washington University, St. Louis, Missouri 63110, USA
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19
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Patlolla A, Ogihara K, Aoki K, Zubkov A, Bengten E, Parent AD, Zhang JH. Hemolysate induces tyrosine phosphorylation and collagen-lattice compaction in cultured fibroblasts. Biochem Biophys Res Commun 1999; 264:100-7. [PMID: 10527848 DOI: 10.1006/bbrc.1999.1383] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Hemolysate, a proposed causative agent for cerebral vasospasm after subarachnoid hemorrhage, produces contraction of cerebral arteries by activation of tyrosine kinases. In addition, hemolysate increases fibroblast-collagen compaction that could play a role in cerebral vasospasm. We studied the effect of hemolysate on tyrosine phosphorylation and fibroblast-collagen compaction in cultured canine basilar and human dermal fibroblasts using tyrosine kinase inhibitors and tyrosine antibodies. Hemolysate enhanced tyrosine phosphorylation of two proteins, 64 and 120 kDa, in cultured canine basilar artery and human dermal fibroblast cells. The effect of hemolysate was time-dependent and concentration-dependent. Oxyhemoglobin and ATP, the two major components of hemolysate, produced similar tyrosine phosphorylation, however, with a different time course. Tyrosine kinase inhibitors genistein and tyrphostin A51 abolished the effect of hemolysate in both cerebral and dermal fibroblasts. Hemolysate increased fibroblast-populated collagen-lattice compaction and tyrosine kinase inhibitors genistein and tyrphostin A51 attenuated the effect of hemolysate. We conclude that hemolysate activates tyrosine kinase that leads to the increase of fibroblast compaction. This effect of hemolysate may contribute to cerebral vasospasm.
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Affiliation(s)
- A Patlolla
- Department of Neurosurgery, University of Mississippi Medical Center, Jackson, Mississippi, 39216, USA
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20
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Luo J, Jankowski J, Tepel M, von Der Giet M, Zidek W, Schlüter H. Identification of diadenosine hexaphosphate in human erythrocytes. Hypertension 1999; 34:872-5. [PMID: 10523376 DOI: 10.1161/01.hyp.34.4.872] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Diadenosine polyphosphates have been identified as important regulators of vascular tone and blood pressure. In reference to the background of the well-known vasoconstriction induced by hemolysate, we questioned whether this action may be due in part to the presence of diadenosine polyphosphates in human erythrocytes. Therefore, erythrocytes were separated from other blood cells and deproteinated. To concentrate and purify nucleotides, the extract was chromatographed by anion exchange, affinity, and reversed-phase columns. In one of the purified fractions, diadenosine hexaphosphate (diadenosine 5', 5'-P(1), P(6) hexaphosphate [AP(6)A]) was identified by matrix-assisted laser desorption/ionization mass spectrometry, ultraviolet spectroscopy, and enzymatic analysis. Hemolysate of erythrocytes injected into the isolated perfused rat kidney induced a dose-dependent vasoconstriction, which was partially inhibited by P(2)-purinoceptor antagonist. The data document the existence of AP(6)A in erythrocytes. AP(6)A may be involved in the pathogenesis of vasospasm induced by free hemoglobin.
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Affiliation(s)
- J Luo
- Medizinische Klinik I, Universitäts-Klinik Marienhospital, University of Bochum, Herne, Germany
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21
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Weir B, Macdonald RL, Stoodley M. Etiology of cerebral vasospasm. ACTA NEUROCHIRURGICA. SUPPLEMENT 1999; 72:27-46. [PMID: 10337411 DOI: 10.1007/978-3-7091-6377-1_3] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/12/2023]
Abstract
Cerebral vasospasm is a gradual onset and prolonged constriction of the cerebral arteries in the subarachnoid space after subarachnoid hemorrhage. The principal cause is the surrounding blood clot. The significance of vasospasm is that flow through the constricted arteries may be reduced sufficiently to cause cerebral infarction. Subarachnoid blood clot is sufficient to cause vasospasm; it does not require additional arterial injury, intracranial hypertension or brain infarction, although these elements are often coexistent. The blood released at the time of aneurysmal rupture into the alien subarachnoid environment is an extraordinarily complex mix of cellular and extracellular elements that evolves as clotting occurs; cells disintegrate; local inflammation, phagocytosis and repair take place; severe constriction alters the metabolism and structure of the arterial wall as well as the balance of vasoconstrictor and dilator substances produced by its endothelium, neurogenic network and perhaps smooth muscle cells.
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Affiliation(s)
- B Weir
- Section of Neurosurgery, Pritzker School of Medicine, University of Chicago, USA
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22
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Iwabuchi S, Marton LS, Zhang JH. Role of protein tyrosine phosphorylation in erythrocyte lysate-induced intracellular free calcium concentration elevation in cerebral smooth-muscle cells. J Neurosurg 1999; 90:743-51. [PMID: 10193620 DOI: 10.3171/jns.1999.90.4.0743] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
OBJECT Tyrosine kinases play an important role in the regulation of systemic vascular smooth-muscle tone. The authors studied the involvement of protein tyrosine kinase activity in erythrocyte lysate-mediated signal transduction in cerebral smooth-muscle cells. METHODS Tyrosine kinase phosphorylation and intracellular free Ca++ ([Ca++]i) were measured in rat aortic and basilar artery smooth-muscle cells by using Western blot and fura 2-acetoxymethyl ester microfluorimetry. Erythrocyte lysate enhanced tyrosine phosphorylation in cultured rat aortic and basilar smooth-muscle cells and induced a rapid transient and a prolonged plateau phase of [Ca++]i response in rat basilar smooth-muscle cells. The tyrosine kinase inhibitors genistein and tyrphostin A51 (administered at concentrations of 30 or 100 microM) attenuated both phases of erythrocyte lysate-induced [Ca++]i elevation. Erythrocyte lysate was separated into low- (<10 kD, which contains adenine nucleotides) and high- (>10 kD, which contains hemoglobin) molecular-weight fractions; these fractions were tested separately in these cells. The low-molecular-weight fraction produced a similar [Ca++]i response to that of erythrocyte lysate and the high-molecular-weight fraction produced a small response. The [Ca++]i responses from both fractions were inhibited by tyrosine kinase inhibitors. CONCLUSIONS To the authors' knowledge, this is the first report to show that tyrosine phosphorylation may be involved in erythrocyte lysate-induced signal transduction and [Ca++]i responses in cerebral smooth-muscle cells.
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Affiliation(s)
- S Iwabuchi
- Department of Neurosurgery, University of Mississippi Medical Center, Jackson 39216-4505, USA
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23
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Kim CJ, Kim KW, Park JW, Lee JC, Zhang JH. Role of tyrosine kinase in erythrocyte lysate-induced contraction in rabbit cerebral arteries. J Neurosurg 1998; 89:289-96. [PMID: 9688125 DOI: 10.3171/jns.1998.89.2.0289] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
OBJECT This study was undertaken to explore whether erythrocyte lysate, a proposed cause of vasospasm, produces vasoconstriction by activation of tyrosine kinase in rabbit cerebral arteries. METHODS Isometric tension was used to monitor contractions in rabbit basilar arteries induced by erythrocyte lysate, 5-hydroxytryptamine (5-HT), or KCl in the absence or presence of tyrosine kinase inhibitors. Erythrocyte lysate, 5-HT, or KCl produced concentration-dependent contractions in rabbit basilar arteries. Preincubation with the tyrosine kinase inhibitors tyrphostin A23 and genistein (30 and 100 microM), but not diadzein, an inactive analog of genistein, attenuated significantly the contraction induced by erythrocyte lysate (p < 0.05). Tyrphostin A23, genistein, and diadzein (30 microM) failed to reduce the contraction caused by 5-HT. Genistein, but not tyrphostin A23 or diadzein (30 microM), attenuated significantly the contraction induced by KCl (p < 0.05). In another series, arterial rings were initially contracted with erythrocyte lysate, 5-HT, or KCl and the relaxant effect of genistein was then tested. Genistein relaxed rabbit basilar arteries that had been contracted by exposure to erythrocyte lysate, 5-HT, or KCl (30-100 microM; p < 0.05). CONCLUSIONS These data indicate that tyrosine kinase may play a role in the regulation of cerebral arterial contraction and tyrosine kinase inhibitors may be useful in the management of cerebral vasospasm.
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Affiliation(s)
- C J Kim
- Department of Neurosurgery, Institute for Medical Sciences, Chonbuk National University, Chonju, Korea.
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24
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Macdonald RL, Zhang J, Weir B, Marton LS, Wollman R. Adenosine triphosphate causes vasospasm of the rat femoral artery. Neurosurgery 1998; 42:825-32; discussion 832-3. [PMID: 9574647 DOI: 10.1097/00006123-199804000-00082] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
OBJECTIVE Adenosine 5'-triphosphate (ATP) causes vasoconstriction by activation of P2-purinoceptors on vascular smooth muscle cells. Erythrocytes contain ATP at a concentration (1.6 mmol/L) that contracts smooth muscle. Previous studies of hemoglobin solutions did not assess whether the vasoactivity was caused by ATP rather than or in addition to hemoglobin. It was hypothesized that the hemolysis of erythrocytes that occurs after subarachnoid hemorrhage releases ATP in concentrations that cause vasospasm. METHODS Thirty-eight rats were randomly assigned to undergo placement of one of the following compounds in a silastic elastomer cuff around each femoral artery: 1) agarose gel (n = 8); 2) dog erythrocyte hemolysate (n = 8); 3) purified human hemoglobin (Hemolink; Hemosol, Inc., Toronto, Canada; n = 8); 4) ATP (n = 8); or 5) clotted autologous blood (n = 6). The amounts of hemoglobins and adenine nucleotides in the compounds were measured by spectrophotometry and high pressure liquid chromatography. Hemolysate, purified hemoglobin, and ATP were mixed with agarose gel to create an artificial clot. Rats were killed and fixed by perfusion at physiological blood pressure 7 days after perivascular cuff and spasmogen placement. Vasospasm was assessed by image analysis of cross sections of fixed femoral arteries. Arteries were assessed for histopathological changes on 3-point scales. RESULTS There was significant variance in arterial diameters among groups (mean diameter +/- standard deviation: agarose gel, 0.29 +/- 0.06; purified hemoglobin, 0.28 +/- 0.04; hemolysate, 0.24 +/- 0.05; ATP, 0.25 +/- 0.05; clotted blood, 0.24 +/- 0.01; P < 0.05, analysis of variance, n = 11-20). Animals exposed to clotted blood, hemolysate that contained ATP, or ATP, developed vasospasm, whereas purified hemoglobin and agarose did not cause vasospasm. Endothelial proliferation and perivascular inflammation were more severe (P < 0.05) in arteries exposed to clotted blood, purified hemoglobin, and hemolysate. CONCLUSION These results suggest that ATP may be a vasospastic substance released by erythrocyte hemolysis. The concentration of ATP in impure solutions of hemoglobin is too low to account for the vasoactivity of these solutions. The discrepancy between arterial narrowing and histopathological changes suggests that either histopathological changes may not be an important correlate of arterial vasospasm or that other substances are important in vasospasm.
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Affiliation(s)
- R L Macdonald
- Department of Surgery, University of Chicago Medical Center, Illinois 60637, USA
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25
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Zhang H, Weir BK, Marton LS, Lee KS, Macdonald RL. P2 purinoceptors in cultured bovine middle cerebral artery endothelial cells. J Cardiovasc Pharmacol 1997; 30:767-74. [PMID: 9436816 DOI: 10.1097/00005344-199712000-00011] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Extracellular adenosine triphosphate (ATP) plays an important role in the regulation of endothelial function. However, its receptors and their signal-transduction pathways in major cerebral arterial endothelial cells are largely unknown. This study was undertaken functionally to classify the P2 purinoceptors in cultured bovine middle cerebral artery endothelial cells by using [Ca2+]i microfluorimetry. The rank order of potency to increase [Ca2+]i was 2-methylthio-ATP approximately ATP approximately uridine triphosphate (UTP) > adenosine diphosphate (ADP) >> adenosine monophosphate (AMP) > alpha,beta-methylene-ATP > adenosine, suggesting that the effect was mediated by both P2y and P2u receptors. ATP, 2-methylthio-ATP, and UTP mobilized Ca2+ from intracellular stores and triggered Ca2+ entry. The effects of ATP, 2-methylthio-ATP, and UTP were reduced by phospholipase C inhibitor 2-nitro-4-carboxyphenyl-N,N-diphenylcarbamate (NCDC), but only the effects of ATP and UTP were attenuated by pertussis toxin, indicating that P2y and P2u receptors may activate the same effector mechanisms by coupling to different G proteins. The [Ca2+]i entry caused by UTP was significantly reduced by the receptor-regulated Ca2+ channel blocker SK&F 96365, by P-450 inhibitor econazole and by inorganic Ca2+ entry blocker lanthanum. P2-receptor antagonists suramin, pyridoxal-phosphate-6-azophenyl-2',4'-disulfonic acid (PPADS), and reactive blue 2 reduced the effects of ATP and 2-methylthio-ATP, but not those of UTP, in a concentration-dependent manner. These studies suggest a coexistence of P2y and P2u receptors in cultured bovine middle cerebral artery endothelial cells.
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Affiliation(s)
- H Zhang
- Department of Surgery, University of Chicago, Illinois, USA
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26
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Sima B, Weir BK, Macdonald RL, Zhang H. Extracellular nucleotide-induced [Ca2+]i elevation in rat basilar smooth muscle cells. Stroke 1997; 28:2053-8; discussion 2059. [PMID: 9341718 DOI: 10.1161/01.str.28.10.2053] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
BACKGROUND AND PURPOSE Extracellular nucleotides play an important role in the regulation of vascular tone and may be involved in cerebral vasospasm after subarachnoid hemorrhage. The objective of this study was to investigate the receptor subtypes for nucleotides and their mechanisms of [Ca2+]i mobilization in cerebral vasculature. METHODS Rat basilar smooth muscle cells were isolated by an enzymatic method. [Ca2+]i response, a large transient peak followed by a slowly decaying plateau. The potency of nucleotides to raise [Ca2+]i was ATP gamma S > or = UDP > or = ATP approximately UDP approximately TTP, indicating that P2u receptors were expressed in the rat basilar smooth muscle cells. The effect of UTP to release Ca2+ from internal stores was reduced by pertussis toxin, by the phospholipase C inhibitor 2-nitro-4-carboxyphenyl N,N-diphenylcarbamate, and by the Ca(2+)-pump inhibitor thapsigargin. The Ca2+ entry induced by UTP was partially attenuated by the receptor-operated Ca2+ channel blocker SK&F96365 and by the voltage-dependent Ca2+ channel blocker verapamil. P2 receptor antagonists suramin and, at higher concentrations, pyridoxal-phosphate-6-azophenyl-2',4'-disulphonic acid reduced the effect of UTP. CONCLUSIONS The results are the first demonstration that nucleotides activate G protein-coupled P2u receptors to mobilize [Ca2+]i in rat basilar smooth muscle cells.
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Affiliation(s)
- B Sima
- Department of Surgery, University of Chicago Ill., USA
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