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E White - One of the best experts on this subject based on the ideXlab platform.
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Cytochalasin D reDuces Ca2+ sensitivity anD maximum tension via interactions with myofilaments in skinneD rat carDiac myocytes.
The Journal of physiology, 2000Co-Authors: S C Calaghan, E White, S Bedut, J Y Le GuennecAbstract:The F-actin Disrupter Cytochalasin D Depresses carDiac contractility, an effect previously ascribeD to the interaction of Cytochalasin D with cytoskeletal actin. We have investigateD the possibility that this negative inotropic effect is Due to the interaction of Cytochalasin D with sarcomeric actin of the thin filament. Confocal images of Triton X-100-skinneD myocytes incubateD with a fluorescent conjugate of Cytochalasin D revealeD a longituDinally striateD pattern of binDing, consistent with a myofibrillar rather than cytoskeletal structure.Tension-pCa relationships were DetermineD at sarcomere lengths (SLs) of 2.0 anD 2.3 [mu]m following 2 min incubation with 1 [mu]M Cytochalasin D. Cytochalasin D significantly reDuceD the pCa for half-maximal activation (pCa50) at both SLs. The shift in pCa50 was significantly greater at a SL of 2.3 [mu]m compareD with that at a SL of 2.0 [mu]m. Cytochalasin D haD no effect on the Hill co-efficient at either SL. Cytochalasin D significantly reDuceD the maximum tension at both SLs. We suggest that the length-DepenDent Decrease in myofilament Ca2+ sensitivity in response to Cytochalasin D is Due to a Decrease in the affinity of troponin C for Ca2+. Cytochalasin D has been useD for many years as the agent of choice for Disruption of cytoskeletal actin. However, we have DemonstrateD for the first time an interaction of Cytochalasin D with sarcomeric actin of the thin filament, which can account for the effects of Cytochalasin D on carDiac contractility.
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Cytochalasin D reDuces Ca2+ sensitivity anD maximum tension via interactions with myofilaments in skinneD rat carDiac myocytes
The Journal of Physiology, 2000Co-Authors: S C Calaghan, E White, S Bedut, J Y Le GuennecAbstract:The F-actin Disrupter Cytochalasin D Depresses carDiac contractility, an effect previously ascribeD to the interaction of Cytochalasin D with cytoskeletal actin. We have investigateD the possibility that this negative inotropic effect is Due to the interaction of Cytochalasin D with sarcomeric actin of the thin filament. Confocal images of Triton X-100-skinneD myocytes incubateD with a fluorescent conjugate of Cytochalasin D revealeD a longituDinally striateD pattern of binDing, consistent with a myofibrillar rather than cytoskeletal structure. Tension–pCa relationships were DetermineD at sarcomere lengths (SLs) of 2.0 anD 2.3 μm following 2 min incubation with 1 μm Cytochalasin D. Cytochalasin D significantly reDuceD the pCa for half-maximal activation (pCa50) at both SLs. The shift in pCa50 was significantly greater at a SL of 2.3 μm compareD with that at a SL of 2.0 μm. Cytochalasin D haD no effect on the Hill co-efficient at either SL. Cytochalasin D significantly reDuceD the maximum tension at both SLs. We suggest that the length-DepenDent Decrease in myofilament Ca2+ sensitivity in response to Cytochalasin D is Due to a Decrease in the affinity of troponin C for Ca2+. Cytochalasin D has been useD for many years as the agent of choice for Disruption of cytoskeletal actin. However, we have DemonstrateD for the first time an interaction of Cytochalasin D with sarcomeric actin of the thin filament, which can account for the effects of Cytochalasin D on carDiac contractility. Within the carDiac cell, actin is founD both in the thin filament anD in cytoskeletal microfilaments. Sarcomeric actin in the thin filament, through interaction with myosin, is responsible for contraction. Cytoskeletal actin has been linkeD with many processes incluDing integration of intracellular space, Determination of the shape of T-tubules anD intracellular organelles, anD moDulation of membrane-bounD ion channels anD exchangers (Moses & Delcarpio, 1983; Messina & Lemanski, 1989; Bennett, 1990; Hilgemann, 1997). Cytochalasin D has been useD as a tool to investigate specifically the role of cytoskeletal actin in a variety of cell types. Cytochalasin D binDs to the barbeD enD of the actin filament at which net polymerisation occurs, thereby preventing aDDition of actin monomers, anD may also binD to a subunit in the interior of an actin filament anD ‘sever’ the filament in two (Brenner & Korn, 1979; Cooper, 1987). It has been thought that the relative stability of sarcomeric actin protects it from the effects of Cytochalasin D. In stuDies using single carDiac cells, isolateD muscle anD the intact perfuseD heart, exposure to Cytochalasin D for between 2 min anD 4 h has been shown to Depress carDiac contractility (Maltsev & UnDrovinas, 1997; Skobel & Kammermeier, 1997; Biermann et al. 1998; Howarth et al. 1998). This effect of Cytochalasin D has been DissociateD from changes in the L-type Ca2+ current, changes in action potential characteristics anD a Decrease in amplituDe of the intracellular Ca2+ transient (Biermann et al. 1998; Howarth et al. 1998; UnDrovinas & Maltsev, 1998). Cytochalasin D has been shown to slow both the rising phase anD Decay of Ca2+ transients in rat ventricular myocytes, anD a moDification of sarcoplasmic reticulum function by Cytochalasin D via cytoskeletal actin has been suggesteD (UnDrovinas & Maltsev, 1998). However, although the negative inotropic effect of Cytochalasin D has been interpreteD in terms of a cytoskeletal action, Howarth et al. (1998) DemonstrateD a shift in the phase-plane relationship between contraction anD Ca2+ in single carDiac myocytes following 2 min perfusion with Cytochalasin D. This observation is consistent with a Decrease in sensitivity of the myofilaments to Ca2+ anD implies an interaction of Cytochalasin D with sarcomeric actin. It is interesting to note, therefore, that the cyclic peptiDe phalloiDin, which also interacts specifically with actin, but in contrast to Cytochalasin D acts to stabilise the actin filament (Cooper, 1987), has been shown to increase myofilament Ca2+ sensitivity (Bukatina et al. 1995). The aim of the present stuDy was to characterise the acute effects of Cytochalasin D on sarcomeric actin filaments. We report for the first time that the effects of Cytochalasin D on contraction anD the kinetics of the Ca2+ transient can be explaineD by an effect on the sarcomeric actin. Our Data allow us to speculate as to the mechanism by which Cytochalasin D exerts its effects on the thin filament.
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RAPID EFFECTS OF Cytochalasin-D ON CONTRACTION AND INTRACELLULAR CALCIUM IN SINGLE RAT VENTRICULAR MYOCYTES
Pflugers Archiv : European journal of physiology, 1998Co-Authors: Frank Christopher Howarth, Mark R. Boyett, E WhiteAbstract:Contraction anD intracellular calcium ([Ca2+]i) transients were recorDeD using a viDeo eDge Detector anD fluorescence spectrophotometry, respectively, in rat ventricular myocytes at 22–24°C stimulateD at a frequency of 1 Hz. Application of the F-actin Disrupter Cytochalasin-D (Cyt-D) causeD a large reDuction in the amplituDe of contraction anD a small increase in the [Ca2+]i transient. These responses began within a few seconDs of application anD were complete after 2 min of exposure. Phase-plane relationships of contraction anD [Ca2+]i were consistent with Cytochalasin-D causing a Decrease in myofilament responsiveness to Ca2+.
Hidde Bult - One of the best experts on this subject based on the ideXlab platform.
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effects of Cytochalasin D eluting stents on intimal hyperplasia in a porcine coronary artery moDel
Cardiovascular Research, 2006Co-Authors: Koen Salu, Johan Bosmans, Yanming Huang, Marc Hendriks, Michel Verhoeven, Anita A.g. Levels, S. J. Cooper, Ivan De Scheerder, Chris J. Vrints, Hidde BultAbstract:Objective: To investigate whether Cytochalasin D-eluting stents (CDES) suppress intimal hyperplasia in porcine coronary arteries anD to compare the efficacy of paclitaxel anD Cytochalasin D as inhibitors of vascular smooth muscle cell (SMC) proliferation anD platelet aggregation in vitro. MethoDs: Rabbit platelet-rich plasma anD SMC cultures DeriveD from rabbit aortas were exposeD to 10−8–10−5 M Cytochalasin D or paclitaxel. Stents Directly coateD with 2 μg Cytochalasin D (low-Dose CDES, n =12) anD bare stents ( n =12) were ranDomly DeployeD in the right anD left coronary artery of 12 pigs. Six weeks later, neointima was stuDieD using quantitative coronary angiography (QCA) anD morphometry. To examine a ten-folD higher Dose, polybutyl methacrylate/polyvinyl acetate-coateD stents were loaDeD with 20 μg Cytochalasin D. High-Dose CDES ( n =10) anD polymer-only stents ( n =11) were DeployeD in 11 pigs. Results: After 7 Days, Cytochalasin D (IC50 9.9 ± 0.4 10−8 M) anD paclitaxel (IC50 1.1 ± 0.4 10−8 M) inhibiteD SMC proliferation in vitro ( n =4). In contrast, Cytochalasin D (10−6–10−5 M, n =5), but not paclitaxel, attenuateD platelet shape change anD aggregation inDuceD by ADP. In vivo QCA showeD less late lumen loss in low-Dose CDES (0.08 ± 0.07 vs. 0.32 ± 0.08 mm, P =0.05), but morphometry DemonstrateD only a tenDency towarD a DecreaseD intimal area. High-Dose CDES inhibiteD both late lumen loss (0.31 ± 0.08 vs. 0.91 ± 0.06 mm, P <0.01) anD intimal area (1.57 ± 0.20 vs. 2.46 ± 0.22 mm2, P <0.01). Immunohistochemistry revealeD that CDES suppresseD peri-strut macrophage recruitment (CD68, P =0.04) anD cell proliferation (Ki67, P =0.03) as compareD to polymer-only stents without interfering with enDothelial cell recovery or the Density of α-SMC actin staining. Thromboses or eDge effects were not observeD in either stuDy. Conclusions: CDES inhibiteD in-stent hyperplasia. The reDuction (39%) with 20 μg CDES was equivalent to that reporteD for paclitaxel-eluting stents in pigs. Interference with platelet aggregation, SMC migration, SMC proliferation, anD leukocyte recruitment coulD contribute to the benefit. The Data inDicate that targeting of actin microfilaments has a potential to suppress in-stent restenosis.
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Effects of Cytochalasin D-eluting stents on intimal hyperplasia in a porcine coronary artery moDel.
Cardiovascular research, 2005Co-Authors: Koen Salu, Johan Bosmans, Yanming Huang, Marc Hendriks, Michel Verhoeven, Anita A.g. Levels, S. J. Cooper, Ivan De Scheerder, Chris J. Vrints, Hidde BultAbstract:Objective: To investigate whether Cytochalasin D-eluting stents (CDES) suppress intimal hyperplasia in porcine coronary arteries anD to compare the efficacy of paclitaxel anD Cytochalasin D as inhibitors of vascular smooth muscle cell (SMC) proliferation anD platelet aggregation in vitro. MethoDs: Rabbit platelet-rich plasma anD SMC cultures DeriveD from rabbit aortas were exposeD to 10−8–10−5 M Cytochalasin D or paclitaxel. Stents Directly coateD with 2 μg Cytochalasin D (low-Dose CDES, n =12) anD bare stents ( n =12) were ranDomly DeployeD in the right anD left coronary artery of 12 pigs. Six weeks later, neointima was stuDieD using quantitative coronary angiography (QCA) anD morphometry. To examine a ten-folD higher Dose, polybutyl methacrylate/polyvinyl acetate-coateD stents were loaDeD with 20 μg Cytochalasin D. High-Dose CDES ( n =10) anD polymer-only stents ( n =11) were DeployeD in 11 pigs. Results: After 7 Days, Cytochalasin D (IC50 9.9 ± 0.4 10−8 M) anD paclitaxel (IC50 1.1 ± 0.4 10−8 M) inhibiteD SMC proliferation in vitro ( n =4). In contrast, Cytochalasin D (10−6–10−5 M, n =5), but not paclitaxel, attenuateD platelet shape change anD aggregation inDuceD by ADP. In vivo QCA showeD less late lumen loss in low-Dose CDES (0.08 ± 0.07 vs. 0.32 ± 0.08 mm, P =0.05), but morphometry DemonstrateD only a tenDency towarD a DecreaseD intimal area. High-Dose CDES inhibiteD both late lumen loss (0.31 ± 0.08 vs. 0.91 ± 0.06 mm, P
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ADDition of Cytochalasin D to a biocompatible oil stent coating inhibits intimal hyperplasia in a porcine coronary moDel.
Coronary artery disease, 2003Co-Authors: Koen Salu, Johan Bosmans, Yanming Huang, Chris J. Vrints, Hidde Bult, Xiaoshun Liu, Lan Wang, Eric Verbeken, Ivan De ScheerderAbstract:BACKGROUND Polymer-baseD, Drug-eluting stents, are currently unDer extensive investigation in the conquest against in-stent restenosis. Concern remains, however, about potential long-term lack of biocompatibility of the polymers useD in these stuDies. Therefore, this stuDy aimeD to evaluate in porcine coronary arteries (1) the in vivo biocompatibility of a new natural, eicosapentaenoic aciD oil stent-coating anD (2) the efficacy of this coating in preventing in-stent restenosis when Cytochalasin D--an inhibitor of actin filament formation, that interferes with cell proliferation anD migration--was aDDeD. METHODS AND RESULTS To assess in vivo biocompatibility of the oil coating, 15 bare anD 15 oil-coateD stents were ranDomly DeployeD in coronary arteries of 15 pigs. No Difference in tissue response, regarDing inflammation or proliferation, was seen between both groups at five Days or at four weeks follow-up. To evaluate the efficacy of the coating in preventing in-stent restenosis by aDDing a potential anti-restenotic Drug, stents were Dip-coateD in 20 mg Cytochalasin D/ml oil solution, resulting in 93 +/- 18 microg Cytochalasin D/stent loaD (n = 3). In vitro Drug release stuDies showeD sustaineD release up to four weeks. Next, 11 oil-coateD anD 11 Cytochalasin D-loaDeD stents were ranDomly implanteD in coronary arteries of 11 pigs. At four weeks, a 39% Decrease in neointimal hyperplasia (p < 0.05, ANCOVA, with injury as covariate) was founD in Cytochalasin D-loaDeD stents compareD to oil-coateD stents. CONCLUSIONS This new natural oil stent-coating shows excellent biocompatibility to vascular tissue. Local Cytochalasin D Delivery from this stent-platform significantly inhibits neointimal hyperplasia in a porcine coronary moDel.
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Effects of local Cytochalasin D Delivery on smooth muscle cell migration anD on collar-inDuceD intimal hyperplasia in the rabbit carotiD artery.
British journal of pharmacology, 2001Co-Authors: Richard H J Bruijns, Hidde BultAbstract:Smooth muscle cell (SMC) migration has been implicateD in neointima formation after angioplasty. Therefore, we investigateD whether Cytochalasin D, a fungal metabolite that inhibits actin filament formation, suppresseD SMC migration anD collar-inDuceD intimal hyperplasia in the rabbit carotiD artery. To establish effective concentrations, contractions of carotiD artery rings to phenylephrine were DetermineD after incubation with Cytochalasin D (10−8 – 10−6 M) for 30 min or 3 Days. In vitro cell migration was stuDieD using carotiD artery explants anD a moDifieD BoyDen chamber with SMCs isolateD from the rabbit aorta. The in vivo effect was testeD after infusion of 10−8 – 10−4 M Cytochalasin D into collars placeD arounD the left carotiD artery; collars placeD arounD the right artery serveD as controls. Contractions to phenylephrine DecreaseD after 30 min or 3 Days exposure to 10−7 anD 10−6 M Cytochalasin D; the effect was partly reversible. These concentrations also inhibiteD cellular outgrowth anD SMC migration in the in vitro assays. Immunohistochemistry showeD that local Delivery of 10−5 or 10−4 M Cytochalasin D for 2 weeks suppresseD collar-inDuceD α-SMC actin expression in the intima by 68% anD 84% respectively. However, the cross-sectional area of the intima was not reDuceD Due to an influx of T-lymphocytes anD macrophages. It is concluDeD that Cytochalasin D suppresseD SMC contractility anD migration in vitro. Although perivascular infusion of Cytochalasin D inhibiteD collar-inDuceD SMC migration from meDia to intima in vivo as well, the intimal hyperplasia was not reDuceD Due to concomitant Development of an inflammatory response. British Journal of Pharmacology (2001) 134, 473–483; Doi:10.1038/sj.bjp.0704281
Ian Zachary - One of the best experts on this subject based on the ideXlab platform.
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Cytochalasin D stimulation of tyrosine phosphorylation anD phosphotyrosine-associateD kinase activity in vascular smooth muscle cells.
Biochemical and biophysical research communications, 1998Co-Authors: Husna Abedi, Ian ZacharyAbstract:The actin filament-Disrupting agent Cytochalasin D strikingly increaseD tyrosine phosphorylation of a 75 kDa protein (p75) in rabbit aortic vascular smooth muscle cells. The microtubule-Disrupting agent, colchicine haD no effect on p75 tyrosine phosphorylation. Cytochalasin D also stimulateD p75-DirecteD kinase activity as DetermineD by kinase assays of anti-Tyr(P) immunoprecipitates. Cytochalasin D stimulateD tyrosine phosphorylation of the F-actin-binDing protein, p80/85 cortactin, but p75 was not immunologically relateD either to cortactin, the phosphatiDylinositol 3'-kinase p85 alpha subunit, or the 80 kDa isoform of calDesmon. These results suggest that p75 may represent a Cytochalasin D-inDucible kinase or kinase-associateD component anD proviDe eviDence for the existence of a potentially novel kinase pathway regulateD by Disruption of the actin cytoskeleton.
Victor A Maltsev - One of the best experts on this subject based on the ideXlab platform.
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Cytochalasin D alters kinetics of ca2 transient in rat ventricular carDiomyocytes an effect of altereD actin cytoskeleton
Journal of Molecular and Cellular Cardiology, 1998Co-Authors: Albertas I Undrovinas, Victor A MaltsevAbstract:The effects of Cytochalasin D, a specific F-actin Depolymerizing agent, on Ca2+ transients in rat ventricular carDiomyocytes were investigateD. Cytochalasin D (20 microM) significantly sloweD Decay of Ca2+ transients (tau Decay control cells=28.1+/-1.3, n=28tau Decay=47.3+/-2.8 ms, n=20, P<0.001). The rising phase of Ca2+ transients was also significantly slower in Cytochalasin D treateD cells (tau rise=5.1+/-0.6 ms, n=17nu tau rise in control cells=3.6+/-0.2, n=21,P<0.01). PhalloiDin (100 microM), an F-actin stabilizer, preventeD Cytochalasin D-inDuceD alterations of Ca2+ transient kinetics. The Cytochalasin D effect was not relateD to the l-type Ca2+ current since the current Density anD kinetics were not altereD by the Drug. We concluDe that integrity of F-actin-baseD cytoskeleton is an important factor for sarcoplasmic reticulum function.
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Cytochalasin D ALTERS KINETICS OF CA2+ TRANSIENT IN RAT VENTRICULAR CARDIOMYOCYTES : AN EFFECT OF ALTERED ACTIN CYTOSKELETON?
Journal of molecular and cellular cardiology, 1998Co-Authors: Albertas I Undrovinas, Victor A MaltsevAbstract:The effects of Cytochalasin D, a specific F-actin Depolymerizing agent, on Ca2+ transients in rat ventricular carDiomyocytes were investigateD. Cytochalasin D (20 microM) significantly sloweD Decay of Ca2+ transients (tau Decay control cells=28.1+/-1.3, n=28tau Decay=47.3+/-2.8 ms, n=20, P
A. C. Leopold - One of the best experts on this subject based on the ideXlab platform.
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Cytochalasin D Does not inhibit gravitropism in roots.
American Journal of Botany, 1997Co-Authors: M. P. Staves, Randy Wayne, A. C. LeopoldAbstract:It is generally thought that seDimenting plastiDs are responsible for gravity sensing in higher plants. We Directly testeD the moDel generateD by the current statolith hypothesis that the gravity sensing that leaDs to gravitropism results from an interaction between the plastiDs anD actin microfilaments. We finD that the primary roots of rice, corn, anD cress unDergo normal gravitropism anD growth even when exposeD to Cytochalasin D, a Disruptor of actin microfilaments. These results inDicate that an interaction between amyloplasts anD the actin cytoskeleton is not critical for gravity sensing in higher plants anD weaken the current statolith hypothesis.
