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001-es BibID:BIBFORM040778
Első szerző:Batta József Tamás (fül-orr-gégész)
Cím:Active and passive behaviour in the regulation of stiffness of the lateral wall in outer hair cells of the guinea-pig / Batta, T. J., Panyi, G., Gaspar, R., Sziklai, I.
Dátum:2003
ISSN:0031-6768
Megjegyzések:The stiffness of the outer hair cell (OHC) lateral wall, measured by the micropipette aspiration technique, is non-linear, decreasing from the ciliary pole (stiffness parameter Sp 1.83+/-0.13 nN/microm n=10) towards the cell base (Sp 1.14+/-0.16 nN/microm, n=10) irrespective of the cochleoapical or cochleobasal origin of the cells. The length of the aspirated lateral wall segment was related exponentially to the duration of the applied negative pressure (6 cm H2O) in the synaptic region of the OHCs whereas an active, sigmoid component was observed between 30 and 60 s in the supranuclear regions. A significant increase of the midlateral wall stiffness (to 1.91+/-0.23 nN/microm; n=10) was observed in calcium-free medium and the sigmoid component of the response of the lateral wall was abolished. Salicylate (5 mM) had no significant effect on the active sigmoid behaviour of the lateral wall (n=10). Gadolinium (5 mM), a non-specific cation channel blocker, increased the stiffness of the lateral wall and attenuated the active component (n=10). The motor protein prestin thus does not seem to be involved in the active stiffness regulation seen in this study. A role for the cortical cytoskeleton in the regulation of stiffness seems reasonable according to our model. The mechanism may involve calcium-dependent metabolic modification of cytoskeletal or membrane proteins.
Tárgyszavak:Orvostudományok Klinikai orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban
Megjelenés:Pflugers Archiv. - 447 : 3 (2003), p. 328-336. -
További szerzők:Panyi György (1966-) (biofizikus) Gáspár Rezső (1944-) (biofizikus) Sziklai István (1954-) (fül-orr-gégész)
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DOI
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2.

001-es BibID:BIBFORM004927
Első szerző:Gáspár Rezső (biofizikus)
Cím:Tetrodotoxin-sensitive fast Na+ current in embryonic chicken osteoclasts / Rezső Gáspár, A. Freek Weidema, Zoltán Krasznai, Peter J. Nijweide, Dirk L. Ypey
Dátum:1995
ISSN:0031-6768
Megjegyzések:A voltage-dependent, fast, transient inward current was characterized in embryonic chicken osteoclasts using the permeabilized patch configuration of the patch-clamp technique. The current was activated by depolarizations to higher than -28 +/- 4 mV from a holding potential of -80 mV. It peaked within 1-1.5 ms, and inactivated within 3.3-6.9 ms. The 50% inactivation voltage was -59 +/- 6 mV with a steepness factor of 0.11 +/- 0.06. The current disappeared with the removal of extracellular Na+ and was reversibly blocked by tetrodotoxin (K0.5 < 15 nM) but not by verapamil (< or = 100 microM). We conclude that this new current in embryonic chicken osteoclasts is a sodium current known from excitable cells.
Tárgyszavak:Orvostudományok Elméleti orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban
Animal
Chick Embryo
Culture Media
drug effects
Hungary
In Vitro
metabolism
Osteoclasts
Patch-Clamp Techniques
pharmacology
Sodium
Sodium Channels
Support,Non-U.S.Gov't
Tetrodotoxin
Verapamil
Megjelenés:Pflügers Archiv. - 430 : 4 (1995), p. 596-598. -
További szerzők:Weidema, Adam Freek (biofizikus) Krasznai Zoltán (1950-) (biofizikus) Nijweide, Peter J. Ypey, Dirk L.
Internet cím:DOI
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3.

001-es BibID:BIBFORM004728
Első szerző:Hajdu Péter (biofizikus)
Cím:Cholesterol modifies the gating of Kv1.3 in human T lymphocytes / Péter Hajdú, Zoltán Varga, Carlo Pieri, György Panyi, Rezső Gáspár
Dátum:2003
ISSN:0031-6768
Megjegyzések:The Kv1.3 potassium channel that belongs to the Shaker family of voltage-gated K(+) channels plays a crucial role in the mitogenic response of T cells. Because it spans the cell membrane its function can be influenced by lipid-protein interactions. In order to study the effect of lipid-protein interactions on the functioning of Kv1.3 we manipulated the membrane cholesterol content in T cells mimicking various physiological conditions by means of the oligosaccharide methyl-beta-cyclodextrin (MbetaCD) and its cholesterol-saturated complex (MbetaCD/C). Fluorescence polarization anisotropy and peak current density were used to monitor the efficiency of cholesterol removal (MbetaCD) and loading (MbetaCD/C). Using whole-cell patch-clamp technique we determined the kinetic and steady-state parameters of activation and inactivation of the Kv1.3 currents under different treatment conditions. Upon elevation of cholesterol content by 1 or 1.5 mg/ml MbetaCD/C the rates of both activation and inactivation were slowed. Moreover, the increased cholesterol level in the membrane resulted in a biphasic activation curve. Cholesterol depletion with MbetaCD (0.95 and 1.425 mg/ml) caused no significant changes in the gating characteristics of Kv1.3. The equilibrium between the open and the closed states of the channels was affected by increased cholesterol content, but at the same time steady-state inactivation was unchanged. We argue that manipulation of membrane cholesterol changed both the kinetic properties of Kv1.3 and steady-state parameters of activation by modifying lipid-protein interactions
Tárgyszavak:Orvostudományok Elméleti orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban
beta-Cyclodextrins
Biophysics
Cell Membrane
Cells
Cholesterol
Cyclodextrins
drug effects
Electric Conductivity
Fluorescence
Fluorescence Polarization
Human
Humans
Hungary
Ion Channel Gating
Kinetics
Kv1.3 Potassium Channel
Lymphocytes
Membrane Microdomains
Membrane Potentials
metabolism
pharmacology
physiology
Potassium
Potassium Channels
Potassium Channels,Voltage-Gated
Research
Support
T-Lymphocytes
Megjelenés:Pflügers Archiv. - 445 : 6 (2003), p. 674-682. -
További szerzők:Varga Zoltán (1969-) (biofizikus, szakfordító) Pieri, Carlo Panyi György (1966-) (biofizikus) Gáspár Rezső (1944-) (biofizikus)
Internet cím:DOI
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