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001-es BibID:	BIBFORM006036
Első szerző:	Gáspár Rezső (biofizikus)
Cím:	Effects of bretylium tosylate on voltage-gated potassium channels in human T lymphocytes / Gaspar, R., Panyi, G., Ypey, D. L., Krasznai, Z., Vereb, G., Pieri, C., Damjanovich, S.
Dátum:	1994
Megjegyzések:	Using the patch-clamp technique, we determined that bretylium tosylate, a quaternary ammonium compound possessing immunomodulating activity, decreased the whole-cell K+ current in human T lymphocytes, in a dose-dependent manner, in the 0.05-5 mM extracellular concentration range. Bretylium tosylate prolonged the recovery from inactivation and accelerated the inactivation and deactivation of the K+ current but did not influence the kinetics of activation or the voltage dependence of activation and steady state inactivation of the K+ conductance. The percentage of drug-induced block was independent of membrane potential. K+ channel block by bretylium tosylate was partially and slowly removable by washing with drug-free extracellular solution. Bovine serum albumin (10 mg/ml) in the bath lifted the drug-induced block almost instantaneously, although not completely. In control experiments bovine serum albumin increased the inactivation time constant of the K+ channels but left the peak K+ current amplitude unaffected. On the basis of the experimental evidence, a gating-dependent allosteric interaction is suggested for the mechanism of drug action. The effective dose range, time of exposure, and reversibility of bretylium tosylate-induced K+ channel block correlated well with the same parameters of the drug-induced inhibition of T lymphocyte activation. The reported effects of bretylium tosylate on T cell mitogenesis can be regarded partly as a consequence of its blocking effects on voltage-gated K+ channels.
Tárgyszavak:	Orvostudományok Elméleti orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban Bretylium Tosylate Cell Membrane drug effects Electrophysiology Human Hungary In Vitro Ion Channel Gating Kinetics Lymphocytes pharmacology physiology Potassium Potassium Channels Support,Non-U.S.Gov't T-Lymphocytes
Megjelenés:	Molecular pharmacology. - 46 : 4 (1994), p. 762-766. -
További szerzők:	Panyi György (1966-) (biofizikus) Ypey, Dirk L. Krasznai Zoltán (1950-) (biofizikus) Vereb György (1965-) (biofizikus, orvos) Pieri, Carlo Damjanovich Sándor (1936-2017) (biofizikus)
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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.
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001-es BibID:	BIBFORM040003
Első szerző:	Krasznai Zoltán (biofizikus)
Cím:	A slow outward current and a hypoosmolality induced anion conductance in embryonic chicken osteoclasts / Krasznai, Z., Weidema, F., Ypey, D. L., Damjanovich, S., Gaspar, R., Marian, T.
Dátum:	2001
ISSN:	0236-5383
Megjegyzések:	In this paper we report on a hypoosmolality induced current, I(osmo), in embryonic chicken osteoclasts, which could only be studied when blocking a simultaneously active, unidentified slow outward current, I(slo). I(slo) was observed in all of the examined cells when both the intracellular and extracellular solutions contained sodium as the major cation and no potassium. The current was outwardly rectifying and activated at membrane potentials more positive than -44 +/- 12 mV (n = 31). The time to half activation of the current was also voltage dependent and was 350 ms at Vm = +80 mV, and 78 ms at Vm = +120 mV. The current did not inactivate during periods up to 5 s. Extracellular 4-AP (5 mM), TEA (5 mM) and Ba2+ (1 mM), blockers of K+ conductances in chicken osteoclasts, did not influence I(slo). However, I(slo) was inhibited by 50 microM extracellular verapamil, which allowed us to study I(osmo) in isolation. Exposure of the osteoclasts to hypotonic solution resulted in the development of a depolarization activated I(osmo). It developed after a 1-min delay and reached its maximum within 10 minutes. Half-maximal activation occurred after 4.4 +/- 0.9 min (n = 9). The current activated within a few ms upon depolarization and did not inactivate during at least 5 sec. I(osmo) reversed around the calculated Nernst potential for Cl- (E(Cl) = +7.3 mV and V(rev) = +5.4 +/- 3.6 mV, n = 9). The underlying conductance, G(osmo) exhibited moderate outward rectification around 0 mV in symmetrical Cl- solutions. Ion substitution experiments showed that G(osmo) is an anion conductance with P(Cl) approximately = P(F) > P(gluc) >> P(Na). I(osmo) was blocked by 0.5 mM SITS but 50 microM verapamil, 5 mM TEA, 5 mM 4-AP, 1 mM Ba2+, 50 microM cytochalasin D and 0.5 mM alendronate did not have any effect on the current. Cl- currents have been implicated in charge neutralization during osteoclastic acid secretion for bone resorption. The present results imply that osmolality may be a factor controlling this charge neutralization.
Tárgyszavak:	Orvostudományok Elméleti orvostudományok idegen nyelvű folyóiratközlemény hazai lapban Animal Anions Calcium Calcium Channel Blockers Chick Embryo Cytochalasin D drug effects Hungary Ion Transport Membrane Potentials metabolism Osmolar Concentration Osteoclasts pharmacology physiology Potassium Sodium Support,Non-U.S.Gov't Verapamil
Megjelenés:	Acta Biologica Hungarica. - 52 : 1 (2001), p. 47-61. -
További szerzők:	Weidema, F. Ypey, Dirk L. Gáspár Rezső (1944-) (biofizikus) Márián Teréz (1950-) (radiobiológus) Damjanovich Sándor (1936-2017) (biofizikus)
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