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D'Adamo MC, Shang L, Imbrici P, Brown SD, Pessia M, Tucker SJ. The Kir5.1 Potassium Channel is an Important Determinant of Neuronal PCO2/pH Sensitivity. Biophys J 2011. [DOI: 10.1016/j.bpj.2010.12.2539] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
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D'Adamo MC, Shang L, Imbrici P, Brown SDM, Pessia M, Tucker SJ. Genetic inactivation of Kcnj16 identifies Kir5.1 as an important determinant of neuronal PCO2/pH sensitivity. J Biol Chem 2011; 286:192-8. [PMID: 21047793 PMCID: PMC3012974 DOI: 10.1074/jbc.m110.189290] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2010] [Revised: 10/28/2010] [Indexed: 11/06/2022] Open
Abstract
The molecular identity of ion channels which confer PCO(2)/pH sensitivity in the brain is unclear. Heteromeric Kir4.1/Kir5.1 channels are highly sensitive to inhibition by intracellular pH and are widely expressed in several brainstem nuclei involved in cardiorespiratory control, including the locus coeruleus. This has therefore led to a proposed role for these channels in neuronal CO(2) chemosensitivity. To examine this, we generated mutant mice lacking the Kir5.1 (Kcnj16) gene. We show that although locus coeruleus neurons from Kcnj16((+/+)) mice rapidly respond to cytoplasmic alkalinization and acidification, those from Kcnj16((-/-)) mice display a dramatically reduced and delayed response. These results identify Kir5.1 as an important determinant of PCO(2)/pH sensitivity in locus coeruleus neurons and suggest that Kir5.1 may be involved in the response to hypercapnic acidosis.
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Affiliation(s)
- M. Cristina D'Adamo
- From the Section of Human Physiology, University of Perugia School of Medicine, Perugia 06100, Italy
| | - Lijun Shang
- the Clarendon Laboratory, Department of Physics, and
- OXION Initiative, University of Oxford, Oxford OX1 3PT, United Kingdom, and
| | - Paola Imbrici
- From the Section of Human Physiology, University of Perugia School of Medicine, Perugia 06100, Italy
| | - Steve D. M. Brown
- OXION Initiative, University of Oxford, Oxford OX1 3PT, United Kingdom, and
- the Medical Research Council Mammalian Genetics Unit, Medical Research Council Harwell, Oxfordshire OX11 ORD, United Kingdom
| | - Mauro Pessia
- From the Section of Human Physiology, University of Perugia School of Medicine, Perugia 06100, Italy
| | - Stephen J. Tucker
- the Clarendon Laboratory, Department of Physics, and
- OXION Initiative, University of Oxford, Oxford OX1 3PT, United Kingdom, and
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Imbrici P, Gualandi F, D'Adamo MC, Masieri MT, Cudia P, De Grandis D, Mannucci R, Nicoletti I, Tucker SJ, Ferlini A, Pessia M. A novel KCNA1 mutation identified in an Italian family affected by episodic ataxia type 1. Neuroscience 2008; 157:577-87. [PMID: 18926884 DOI: 10.1016/j.neuroscience.2008.09.022] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2008] [Revised: 09/11/2008] [Accepted: 09/11/2008] [Indexed: 10/21/2022]
Abstract
Episodic ataxia type 1 (EA1) is a rare human neurological syndrome characterized by continuous myokymia and attacks of generalized ataxia that can be triggered by abrupt movements, emotional stress and fatigue. An Italian family has been identified where related members displayed continuous myokymia, episodes of ataxia, attacks characterized by myokymia only, and neuromyotonia. A novel missense mutation (F414C), in the C-terminal region of the K(+) channel Kv1.1, was identified in the affected individuals. The mutant homotetrameric channels were non-functional in Xenopus laevis oocytes. In addition, heteromeric channels resulting from the co-expression of wild-type Kv1.1 and Kv1.1(F414C), or wild-type Kv1.2 and Kv1.1(F414C) subunits displayed reduced current amplitudes and altered gating properties. This indicates that the pathogenic effect of this KCNA1 mutation is likely to be related to the defective functional properties we have identified.
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Affiliation(s)
- P Imbrici
- Section of Human Physiology, Department of Internal Medicine, University of Perugia School of Medicine, Via del Giochetto, I-06126 Perugia, Italy
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Casamassima M, D'Adamo MC, Pessia M, Tucker SJ. Identification of a heteromeric interaction that influences the rectification, gating, and pH sensitivity of Kir4.1/Kir5.1 potassium channels. J Biol Chem 2003; 278:43533-40. [PMID: 12923169 DOI: 10.1074/jbc.m306596200] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Heteromultimerization between different potassium channel subunits can generate channels with novel functional properties and thus contributes to the rich functional diversity of this gene family. The inwardly rectifying potassium channel subunit Kir5.1 exhibits highly selective heteromultimerization with Kir4.1 to generate heteromeric Kir4.1/Kir5.1 channels with unique rectification and kinetic properties. These novel channels are also inhibited by intracellular pH within the physiological range and are thought to play a key role in linking K+ and H+ homeostasis by the kidney. However, the mechanisms that control heteromeric K+ channel assembly and the structural elements that generate their unique functional properties are poorly understood. In this study we identify residues at an intersubunit interface between the cytoplasmic domains of Kir5.1 and Kir4.1 that influence the novel rectification and gating properties of heteromeric Kir4.1/Kir5.1 channels and that also contribute to their pH sensitivity. Furthermore, this interaction presents a structural mechanism for the functional coupling of these properties and explains how specific heteromeric interactions can contribute to the novel functional properties observed in heteromeric Kir channels. The highly conserved nature of this structural association between Kir subunits also has implications for understanding the general mechanisms of Kir channel gating and their regulation by intracellular pH.
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Affiliation(s)
- Maria Casamassima
- Istituto di Ricerche Farmacologiche "Mario Negri," Consorzio Mario Negri Sud, 66030 Santa Maria Imbaro (Chieti), Italy
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Corsaro A, Thellung S, Russo C, Villa V, Arena S, D'Adamo MC, Paludi D, Rossi Principe D, Damonte G, Benatti U, Aceto A, Tagliavini F, Schettini G, Florio T. Expression in E. coli and purification of recombinant fragments of wild type and mutant human prion protein. Neurochem Int 2002; 41:55-63. [PMID: 11918972 DOI: 10.1016/s0197-0186(01)00137-1] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Prion diseases are fatal neurodegenerative disorders of the CNS of men and animals, characterized by spongiform degeneration of the CNS, astrogliosis and deposition of amyloid into the brain. The conversion of a cellular glycoprotein (the prion protein, PrP(C)) into an altered isoform (the prion scrapie, PrP(Sc)), which accumulates within the brain tissue by virtue of its resistance to the intracellular catabolism, is currently believed to represent the etiologic agent responsible for these diseases. Synthetic or recombinant polypeptides are commonly used to elucidate the mechanism of proteins involved in neurodegenerative diseases. Here we describe a procedure, which allows the synthesis and purification in its native folding, of the human prion protein fragment 90-231, corresponding to the protease resistant core of PrP(Sc). We synthesized the polypeptides 90-231 of both the wild type and the E200K mutant isoforms of PrP. Using a gluthatione S-transferase (GST) fusion protein approach, milligram amounts of polypeptides were obtained after expression in E. coli. The recovery of the purified fusion protein was monitored following the evaluation of the GST activity. The PrP fragment was released from the fusion protein immobilized on a glutathione-coupled agarose resin by direct cleavage with thrombin. The recombinant protein was identified by comassie stained acrylamide gel and by immunoblotting employing a monoclonal anti-PrP antibody. The peptide purified by gel filtration chromatography showed mainly an alpha-helix structure, as analysed by circular dichroism (CD) and an intact disulfide bridge. The same procedure was also successfully employed to synthesize and purify the E200K mutant PrP fragment.
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Affiliation(s)
- A Corsaro
- Pharmacology and Neuroscience, National Institute for Cancer Research (IST), c/o Advanced Biotechnology Center (CBA), Genoa, Italy
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De Curtis A, D'Adamo MC, Amore C, Polishchuck R, Castelnuovo AD, Donati MB, Iacoviello L. Experimental arterial thrombosis in genetically or diet induced hyperlipidemia in rats--role of vitamin K-dependent clotting factors and prevention by low-intensity oral anticoagulation. Thromb Haemost 2001; 86:1440-8. [PMID: 11776312] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/23/2023]
Abstract
To investigate the relationship among lipids, coagulation and thrombosis in the absence of atherosclerosis, spontaneous or dietary-induced hyperlipidemic (FHL) rats were studied. FHL showed higher levels of coagulation factors VII, IX, X, VIII and XII and a shortening of the occlusion time (OT) of an artificial arterial prosthesis as compared with normolipidemic (FNL) animals. Damage of abdominal aorta of FHL was followed by increased fibrin deposition in the vascular intima as compared to FNL. After 5 months of cholesterol-rich diet FNL showed increased cholesterol, triglycerides and factor II, VII, IX, X, XII levels. A significant shortening of the OT and increased fibrin deposition was also observed. Two-month diet withdrawal restored the initial condition. Warfarin treatment, at a dose decreasing vitamin K-dependent factor to levels found in FNL, prolonged the OT and reduced fibrin deposition, without modifying F XII or changing lipid profile. An increase in the activated form of F VII was observed. In contrast, no difference was found in F VII clearance. High lipid levels favour the process of thrombus formation by increasing the activation of vitamin K-dependent coagulation factors. Low-dose warfarin treatment reverts the prothrombotic effect of hyperlipidemia.
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Affiliation(s)
- A De Curtis
- Angela Valenti Laboratory of Genetic and Environmental Risk Factors for Thrombotic Disease, Consorzio Mario Negri Sud, Santa Maria Imbaro, Italy
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Pessia M, Imbrici P, D'Adamo MC, Salvatore L, Tucker SJ. Differential pH sensitivity of Kir4.1 and Kir4.2 potassium channels and their modulation by heteropolymerisation with Kir5.1. J Physiol 2001; 532:359-67. [PMID: 11306656 PMCID: PMC2278540 DOI: 10.1111/j.1469-7793.2001.0359f.x] [Citation(s) in RCA: 101] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
1. The inwardly rectifying potassium channel Kir5.1 appears to form functional channels only by coexpression with either Kir4.1 or Kir4.2. Kir4.1-Kir5.1 heteromeric channels have been shown to exist in vivo in renal tubular epithelia. However, Kir5.1 is expressed in many other tissues where Kir4.1 is not found. Using Kir5.1-specific antibodies we have localised Kir5.1 expression in the pancreas, a tissue where Kir4.2 is also highly expressed. 2. Heteromeric Kir5.1-Kir4.1 channels are significantly more sensitive to intracellular acidification than Kir4.1 currents. We demonstrate that this increased sensitivity is primarily due to modulation of the intrinsic Kir4.1 pH sensitivity by Kir5.1. 3. Kir4.2 was found to be significantly more pH sensitive (pK(a) = 7.1) than Kir4.1 (pK(a) = 5.99) due to an additional pH-sensing mechanism involving the C-terminus. As a result, coexpression with Kir5.1 does not cause a major shift in the pH sensitivity of the heteromeric Kir4.2-Kir5.1 channel. 4. Cell-attached single channel analysis of Kir4.2 revealed a channel with a high open probability (P(o) > 0.9) and single channel conductance of approximately 25 pS, whilst coexpression with Kir5.1 produced novel bursting channels (P(o) < 0.3) and a principal conductance of approximately 54 pS with several subconductance states. 5. These results indicate that Kir5.1 may form heteromeric channels with Kir4.2 in tissues where Kir4.1 is not expressed (e.g. pancreas) and that these novel channels are likely to be regulated by changes in intracellular pH. In addition, the extreme pH sensitivity of Kir4.2 has implications for the role of this subunit as a homotetrameric channel.
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Affiliation(s)
- M Pessia
- Department of Vascular Medicine and Pharmacology, Istituto di Ricerche Farmacologiche 'Mario Negri', Consorzio Mario Negri Sud, 66030 Santa Maria Imbaro (Chieti), Italy.
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8
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Imbrici P, Tucker SJ, D'Adamo MC, Pessia M. Role of receptor protein tyrosine phosphatase alpha (RPTPalpha) and tyrosine phosphorylation in the serotonergic inhibition of voltage-dependent potassium channels. Pflugers Arch 2000; 441:257-62. [PMID: 11211111 DOI: 10.1007/s004240000406] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
The activity of voltage-gated potassium (Kv) channels can be dynamically modulated by several events, including neurotransmitter-stimulated biochemical cascades mediated by G-protein-coupled receptors. By using a heterologous expression system, we show that activating the 5-HT2C receptor inhibits both Kv1.1 and Kv1.2 channels through a tyrosine phosphorylation mechanism. The major molecular determinants of channel inhibition were identified as two tyrosine residues located in the N-terminal region of the Kv channel subunit. Furthermore, we demonstrate that receptor protein tyrosine phosphatase alpha (RPTPalpha), a receptor protein tyrosine phosphatase, co-ordinates the inhibition process mediated via 5-HT2C receptors. We therefore propose that the serotonergic regulation of human Kv1.1 and Kv1.2 channel activity by the 5-HT2C receptor involves the dual coordination of both RPTPalpha and specific tyrosine kinases coupled to this receptor.
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Affiliation(s)
- P Imbrici
- Istituto di Ricerche Farmacologiche Mario Negri, Consorzio Mario Negri Sud, Department of Vascular Medicine and Pharmacology, Chieti, Italy
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De Curtis A, D'Adamo MC, Amore C, Donati MB, Iacoviello L. Effects of dyslipidemia on t-PA release in rats. Thromb Haemost 2000; 84:734-5. [PMID: 11057885] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/18/2023]
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Tucker SJ, Imbrici P, Salvatore L, D'Adamo MC, Pessia M. pH dependence of the inwardly rectifying potassium channel, Kir5.1, and localization in renal tubular epithelia. J Biol Chem 2000; 275:16404-7. [PMID: 10764726 DOI: 10.1074/jbc.c000127200] [Citation(s) in RCA: 101] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The physiological role of the inwardly rectifying potassium channel, Kir5.1, is poorly understood, as is the molecular identity of many renal potassium channels. In this study we have used Kir5.1-specific antibodies to reveal abundant expression of Kir5.1 in renal tubular epithelial cells, where Kir4.1 is also expressed. Moreover, we also show that Kir5.1/Kir4.1 heteromeric channel activity is extremely sensitive to inhibition by intracellular acidification and that this novel property is conferred predominantly by the Kir5.1 subunit. These findings suggest that Kir5.1/Kir4.1 heteromeric channels are likely to exist in vivo and implicate an important and novel functional role for the Kir5.1 subunit.
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Affiliation(s)
- S J Tucker
- University Laboratory of Physiology, Parks Road, Oxford OX1 3PT, United Kingdom.
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11
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D'Adamo MC, Imbrici P, Sponcichetti F, Pessia M. Mutations in the KCNA1 gene associated with episodic ataxia type-1 syndrome impair heteromeric voltage-gated K(+) channel function. FASEB J 1999; 13:1335-45. [PMID: 10428758 DOI: 10.1096/fasebj.13.11.1335] [Citation(s) in RCA: 65] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Episodic ataxia type-1 syndrome (EA-1) is an autosomal dominant neurological disorder that manifests itself during infancy and results from point mutations in the voltage-gated potassium channel gene hKv1.1. The hallmark of the disease is continuous myokymia and episodic attacks of spastic contractions of the skeletal muscles, which cause permanent disability. Coexpression of hKv1.1 and hKv1.2 subunits produces heteromeric potassium channels with biophysical and pharmacological properties intermediate between the respective homomers. By using tandemly linked subunits, we demonstrate that hKv1.1 subunits bearing the EA-1 mutations V408A and E325D combine with hKv1.2 to produce channels with altered kinetics of activation, deactivation, C-type inactivation, and voltage dependence. Moreover, hKv1.1V408A single-channel analysis reveals a approximately threefold reduction of the mean open duration of the channel compared with the wild-type, and this mutation alters the open-state stability of both homomeric and heteromeric channels. The results demonstrate that human Kv1.2 and Kv1.1 subunits coassemble to form a novel channel with distinct gating properties that are altered profoundly by EA-1 mutations, thus uncovering novel physiopathogenetic mechanisms of episodic ataxia type-1 myokymia syndrome.
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Affiliation(s)
- M C D'Adamo
- Istituto di Ricerche Farmacologiche [Mario Negri], Consorzio Mario Negri Sud, Department of Pharmacology and Molecular Pathology, Chieti, Italy
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Salvatore L, D'Adamo MC, Polishchuk R, Salmona M, Pessia M. Localization and age-dependent expression of the inward rectifier K+ channel subunit Kir 5.1 in a mammalian reproductive system. FEBS Lett 1999; 449:146-52. [PMID: 10338121 DOI: 10.1016/s0014-5793(99)00420-2] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Kir 5.1 is a member of the inward rectifier potassium channel superfamily which does not form functional channels when expressed by itself in Xenopus laevis oocytes. rt-PCR reveals high levels of Kir 5.1 mRNA expression in testis but the function of this channel remains unknown. To determine the cell-specific expression of this channel in the testis we raised a polyclonal antibody against an external epitope of Kir 5.1 and tested its specificity in Xenopus oocytes expressing several cloned Kir subunits. Strong immunoreactivity for Kir 5.1 was found in seminiferous tubules of rat testis and, particularly, in spermatogonia, primary and secondary spermatocytes, spermatids and in the head and body of spermatozoa. The intensity of Kir 5.1 immunofluorescence, quantified using laser scanning microscopy, increased with age at every stage in the development of sperm from spermatogonia and reached a peak in 60-day-old rats. In contrast, the immunofluorescence decreased in 90-day-old animals and was detected mostly in spermatozoa. The results demonstrate that Kir 5.1 expression in the testis is localised to cells involved in spermatogenesis, showing a temporal pattern of expression during sexual maturity.
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Affiliation(s)
- L Salvatore
- Istituto di Ricerche Farmacologiche Mario Negri, Consorzio Mario Negri Sud, Santa Maria Imbaro (Chieti), Italy
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D'Adamo MC, Liu Z, Adelman JP, Maylie J, Pessia M. Episodic ataxia type-1 mutations in the hKv1.1 cytoplasmic pore region alter the gating properties of the channel. EMBO J 1998; 17:1200-7. [PMID: 9482717 PMCID: PMC1170468 DOI: 10.1093/emboj/17.5.1200] [Citation(s) in RCA: 70] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Episodic ataxia type-1 is a rare human neurological syndrome which occurs during childhood and persists through the whole life of affected patients. Several heterozygous point mutations have been found in the coding sequence of the voltage-gated potassium channel gene hKv1.1 of different affected families. V408A and E325D mutations are located in the cytoplasmic putative pore region of hKv1.1 channels and profoundly alter their gating properties. V408A channels showed increased kinetic rates of activation, deactivation and C-type inactivation. Expression of E325D channels in Xenopus oocytes led to an approximately 13-fold current amplitude reduction and to a 52.4 mV positive shift in the voltage dependence of activation. Moreover, the E325D mutation altered the kinetics of activation, deactivation, C-type inactivation and channel open probability. Heteromeric channels composed of two wild-type and two mutated subunits, linked as dimers, showed gating properties intermediate between channels formed from four normal or four mutated subunits. The results demonstrate that the highly conserved residues Val408 and Glu325 play a pivotal role in several gating processes of a human potassium channel, and suggest a pathogenetic mechanism by which the impairment of the delayed-rectifier function of affected neurons is related to the type and number of mutated subunits which make up the hKv1.1 channels.
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Affiliation(s)
- M C D'Adamo
- Istituto di Ricerche Farmacologiche 'Mario Negri', Consorzio Mario Negri Sud, 66030 Santa Maria Imbaro, Italy
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14
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Iacoviello L, D'Adamo MC, Pawlak K, Polishchuck R, Wollny T, Buczko W, Donati MB. Antithrombotic activity of dermatan sulphates, heparins and their combination in an animal model of arterial thrombosis. Thromb Haemost 1996; 76:1102-7. [PMID: 8972038] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Dermatan sulphates have been shown to inhibit thrombus formation and thrombus growth in different experimental model of venous thrombosis. At variance with heparins, they show a remarkably low haemorrhagic potential. On the other hand, very few data are available on the effect of dermatan sulphates on arterial thrombus formation. We evaluated the effects of a low molecular weight (LMW)-dermatan sulphate, a high molecular weight (HMW)-dermatan sulphate and sulodexide (a mixture of fast-moving heparin fraction and dermatan sulphate) in comparison with LMW- and HMW-heparin, in a model of arterial thrombosis in rats. The insertion of an artificial prosthesis into the abdominal aorta of the animals induced the formation of an occluding thrombus within 2-5 days. The time in which 50% of the loops became occluded (OT50) was also calculated and used to compare the efficacy of the different drug treatments. This was 2.84 days for control animals and 4.25 and 5.80 days for HMW- and LMW-dermatan sulphate, respectively. Neither drug changed the "template" bleeding time, even at higher doses. In contrast, HMW-heparin at doses (8 mg/kg, sc, twice a day) inducing an antithrombotic activity comparable to that of dermatan sulphates, dramatically prolonged the bleeding time. LMW-heparin at the same doses was ineffective. Sulodexide (10 mg/Kg, sc, twice a day) prolonged the occlusion time to the same extent as HMW-heparin (OT50 5.10 vs. 4.14 days), with less an effect on the bleeding time (144 +/- 6 s vs. > 300 s, respectively). Histological examination confirms that the prolongation of occlusion time induced by the drugs is really related to thrombus formation inhibition at the site of arterial wall injury. Acetyl salicylic acid (ASA) (100 mg/kg/day in drinking water as lysine acetylsalicylate) did not modify the effect of Desmin 370 and Sulodexide on both occlusion and bleeding time. However, while it did not increase the antithrombotic activity of HMW-heparin, it significantly prolonged its haemorrhagic effect. In conclusion, dermatan sulphates are effective inhibitors of arterial thrombosis in rats, without inducing bleeding complications.
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Affiliation(s)
- L Iacoviello
- Angela Valenti Laboratory of Thrombosis Pharmacology, Consorzio Mario Negri Sud, Santa Maria Imbaro, Italy
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15
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Chabielska E, Kolpakov V, D'Adamo MC, De Curtis A, Buczko W, Iacoviello L, Donati MB. Morphological and hemostatic changes in rats with abdominal arterial prosthesis. Thromb Res 1996; 82:69-77. [PMID: 8731511 DOI: 10.1016/0049-3848(96)00052-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
We evaluated the changes over time in hemostatic factors during ongoing arterial thrombosis in rats, as induced by a loop-shaped aortic prosthesis. Moreover, we investigated this condition by inspecting in parallel local thrombus growth, systemic vascular prostacyclin and t-PA production. One minute after loop insertion, activated platelets spread on the internal surface of the prosthesis and 24 hrs later numerous platelet aggregates supported by a fibrin network could be observed. However, no evidence for platelet activation could be concomitantly found in peripheral blood. A sustained increased in PGI2 formation was detected together with a progressive increase in plasma fibrinolytic activity during thrombus growth. The levels of fibrinogen as well as antithrombin III (ATIII) and heparin cofactor II (HCII) activities were steadily increased in loop-bearing animals. In conclusion, the dynamic phases of thrombus formation, in an aortic prosthesis, produce changes in vascular function and in hemostatic factors at the level of systemic blood.
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Affiliation(s)
- E Chabielska
- Laboratory of Thrombosis Pharmacology, Istituto di Ricerche Farmacologiche Mario Negri, Consorzio Mario Negri Sud, Santa Maria Imbaro, Italy
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16
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Iacoviello L, D'Adamo MC, Buczko W, Donati MB. Amiloride inhibits tissue-type plasminogen activator (t-PA) release from vascular endothelium. Thromb Haemost 1995; 74:808-9. [PMID: 8585035] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
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17
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Iacoviello L, D'Adamo MC, De Curtis A, Buczko W, Donati MB. Enhanced vascular plasminogen activator (t-PA) release by epinephrine in aged rats. Thromb Haemost 1995; 73:841-4. [PMID: 7482413] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Adrenergic stimulation induces an acute fibrinolytic response in the vascular wall and can play an important role in limiting thrombus growth. The incidence of thrombotic disease increases with age. As many adrenergic functions are affected by aging, the vascular response to adrenergic stimulation was studied in young (3 +/- 1 months) and aged (18 +/- 3 months) rats, using an experimental model of vascular perfusion. Five min epinephrine (EPI) infusion (0.15-25 microM) induced a dose-dependent increase in tissue-type plasminogen activator (t-PA) release and in perfusion pressure, in both young and aged rats. In the latter, however, the basal activity of t-PA was significantly higher than in young animals (0.22 +/- 0.02 vs 0.13 +/- 0.01 U/ml; means +/- SE; p < 0.01, n = 40) and EPI infusion induced a significantly higher increase in t-PA activity (0.78 +/- 0.06 vs 0.47 +/- 0.08 U/ml, p < 0.01, for 6.25 microM EPI). The response was characterized by a delayed onset. In contrast, the increase in the perfusion pressure by EPI was significantly lower in aged that in young rats, its basal levels being normal. To evaluate whether the increased vascular response of t-PA was peculiar for adrenergic stimulation, we infused platelet activating factor (PAF), an inducer of t-PA release, not related to catecholamines. PAF, during five-minute infusion induced a rapid and dose-dependent (100-1250 pM) increase in t-PA release, to the same extent in both young and aged rats. In conclusion, basal t-PA secretion was increased in aged rats probably as a response of vascular endothelium to chronic stimulation.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- L Iacoviello
- Laboratory of Thrombosis Pharmacology, Istituto di Ricerche Farmacologiche Mario Negri, Consorzio Mario Negri Sud, Santa Maria Imbaro, Italy
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Kolpakov V, D'Adamo MC, Salvatore L, Amore C, Mironov A, Iacoviello L, Donati MB. Neutrophil derived cathepsin G induces potentially thrombogenic changes in human endothelial cells: a scanning electron microscopy study in static and dynamic conditions. Thromb Haemost 1994; 72:140-5. [PMID: 7974362] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Activated neutrophils may promote thrombus formation by releasing proteases which may activate platelets, impair the fibrinolytic balance and injure the endothelial monolayer. We have investigated the morphological correlates of damage induced by activated neutrophils on the vascular wall, in particular the vascular injury induced by released cathepsin G in both static and dynamic conditions. Human umbilical vein endothelial cells were studied both in a cell culture system and in a model of perfused umbilical veins. At scanning electron microscopy, progressive alterations of the cell monolayer resulted in cell contraction, disruption of the intercellular contacts, formation of gaps and cell detachment. Contraction was associated with shape change of the endothelial cells, that appeared star-like, while the underlying extracellular matrix, a potentially thrombogenic surface, was exposed. Comparable cellular response was observed in an "in vivo" model of perfused rat arterial segment. Interestingly, cathepsin G was active at lower concentrations in perfused vessels than in culture systems. Restoration of blood flow in the arterial segment previously damaged by cathepsin G caused adhesion and spreading of platelets on the surface of the exposed extracellular matrix. The subsequent deposition of a fibrin network among adherent platelets, could be at least partially ascribed to the inhibition by cathepsin G of the vascular fibrinolytic potential. This study supports the suggestion that the release of cathepsin G by activated neutrophils, f.i. during inflammation, may contribute to thrombus formation by inducing extensive vascular damage.
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Affiliation(s)
- V Kolpakov
- Laboratory of Thrombosis Pharmacology, Istituto di Ricerche Farmacologiche Mario Negri, Consorzio Mario Negri Sud, Santa Maria Imbaro, Italy
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Iacoviello L, De Curtis A, D'Adamo MC, Amore C, Buczko W, De Gaetano G, Donati MB. Prostacyclin is required for t-PA release after venous occlusion. Am J Physiol 1994; 266:H429-34. [PMID: 7511345 DOI: 10.1152/ajpheart.1994.266.2.h429] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
The role of vascular cyclooxygenase pathway on tissue-type plasminogen activator (t-PA) release after venous occlusion was studied in anesthetized rats. After the inferior vena cava was clamped for 30 min, fibrinolytic activity increased from 143.7 +/- 14.5 to 209.5 +/- 10.3 mm2 (mean +/- SE, P < 0.002). This increase was prevented by aspirin at high (100 mg/kg i.v.) but not at low doses (1 mg/kg i.v.). Dazoxiben (10 mg/kg i.v.), an inhibitor of thromboxane synthase, was ineffective on the fibrinolytic response. Both the basal levels of 6-ketoprostaglandin F1 alpha and its increase after venous occlusion were suppressed by 100 mg/kg aspirin administration (from 0.64 +/- 0.2 to 0.05 +/- 0.002 ng/ml before occlusion, P < 0.001; and from 1.08 +/- 0.2 to 0.06 +/- 0.002 ng/kg after occlusion, P < 0.001), whereas they were both unaffected by aspirin at low doses (from 0.53 +/- 0.06 before to 1.20 +/- 0.08 ng/ml after stasis). Moreover, iloprost, a stable analogue of prostacyclin, reversed the aspirin inhibitory effects on fibrinolytic activity by restoring t-PA vascular release after venous stasis. Our results provide experimental evidence that an intact cyclooxygenase pathway in vascular wall is required for the fibrinolytic activity increase after venous occlusion in rats.
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Affiliation(s)
- L Iacoviello
- Laboratory of Thrombosis Pharmacology, Istituto di Ricerche Farmacologiche Mario Negri, Santa Maria Imbaro, Italy
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Iacoviello L, De Curtis A, Amore C, D'Adamo MC, Buczko W, de Gaetano G, Donati MB. Effect of aspirin on the fibrinolytic response in perfused rat hindquarters. Eur J Pharmacol 1992; 229:39-44. [PMID: 1473562 DOI: 10.1016/0014-2999(92)90283-a] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The role of aspirin on tissue plasminogen activator (t-PA) release was studied in rats after experimental venous occlusion. For this purpose, we developed a new experimental model which combines a vascular perfusion system (isolated rat hindquarters) with vascular stimulation, namely the application of venous stasis. Application of venous stasis for 30 min induced the release of t-PA from the vascular endothelium into the perfusate (from 0.19 +/- 0.05 to 0.39 +/- 0.05 UI/ml), reaching a peak 90 s after reperfusion. Aspirin administered to rats 60 min before the experiments (100 mg/kg i.v.), or dissolved in Tyrode solution (100 microM), suppressed 6-keto-prostaglandin F1 alpha (6-keto-PGF1 alpha) synthesis (0.38 +/- 0.09 in control and < 0.01 and 0.15 +/- 0.09 ng/ml, respectively, in aspirin-treated groups) but did not prevent the increase in fibrinolytic activity after venous occlusion (from 0.20 +/- 0.04 to 0.38 +/- 0.06 and from 0.07 +/- 0.03 to 0.27 +/- 0.03 IU/ml, respectively, in the aspirin-treated group). Our results suggest that the increase in fibrinolytic activity after experimental venous occlusion in isolated rat hindlegs is modulated by mechanism(s) other than the cyclooxygenase pathway in the vascular wall.
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Affiliation(s)
- L Iacoviello
- Laboratory of Thrombosis Pharmacology, Istituto di Ricerche Farmacologiche Mario Negri, Consorzio Mario Negri Sud, Santa Maria Imbaro, Italy
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