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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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001-es BibID:	BIBFORM029944
Első szerző:	Márián Teréz (radiobiológus)
Cím:	Hypoglycemia activates compensatory mechanism of glucose metabolism of brain / Marian, T., Balkay, L., Fekete, I., Lengyel, Z., Veress, G., Esik, O., Tron, L., Krasznai, Z.
Dátum:	2001
ISSN:	0236-5383
Megjegyzések:	The effect of plasma glucose concentration on the cerebral uptake of [18F]-fluorodeoxy-D-glucose (FDG) was studied in a broad concentration range in a rabbit brain model using dynamic FDG PET measurements. Hypoglycemic and hyperglycemic conditions were maintained by manipulating plasma glucose applying i.v. glucose or insulin load. FDG utilization (K) and cerebral glucose metabolic rate (CGMR) were evaluated in a plasma glucose concentration range between 0.5 mM and 26 mM from the kinetic constant k1, k2, k3 obtained by the Sokoloff model of FDG accumulation. A decreasing set of standard FDG uptake values found with increasing blood glucose concentration was explained by competition between the plasma glucose and the radiopharmacon FDG. A similar trend was observed for the forward kinetic constants k1, and k3 in the entire concentration range studied. The same decreasing tendency of k2 was of a smaller magnitude and was reverted at the lowest glucose concentrations where a pronounced decrease of this backward transport rate constant was detected. Our kinetic data indicate a modulation of the kinetics of carbohydrate metabolism by the blood glucose concentration and report on a special mechanism compensating for the low glucose supply under conditions of extremely low blood glucose level.
Tárgyszavak:	Orvostudományok Klinikai orvostudományok idegen nyelvű folyóiratközlemény hazai lapban
Megjelenés:	Acta Biologica Hungarica. - 52 : 1 (2001), p. 35-45. -
További szerzők:	Balkay László (1963-) (biofizikus) Fekete István (1951-) (neurológus, pszichiáter) Lengyel Zsolt (nukleáris medicina szakorvos) Veress Gábor (1971-) (neurobiológus) Ésik Olga Trón Lajos (1941-) (biofizikus) Krasznai Zoltán (1950-) (biofizikus)
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