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001-es BibID:	BIBFORM049392
Első szerző:	Csernoch László (élettanász)
Cím:	The Low Affinity Calcium Buffer TPEN Alters Calcium Release From the Sarcoplasmic Reticulum (SR) of Mammalian Skeletal Muscle / Laszlo Csernoch, Cecilia Simut, János Almássy, Carole Jung, Ernst Niggli, István Jona
Dátum:	2005
ISSN:	0006-3495
Megjegyzések:	Recent experiments suggested that chelating calcium within the SR using phosphate in the intracellular solution of skinned mammalian skeletal muscle fibers leads to the increase in the frequency of elementary calcium release events (ECRE) as observed under laser scanning confocal microscopy (Csernoch et al. 2003. Biophys. J. 84, 386a). To understand if this phenomenon was solely due to the buffering of intra SR calcium we incubated our saponin skinned, Fluo-4 loaded fibers with the low affinity membrane permeant buffer N,N,N',N'-tetrakis (2-pyridylmethyl)ethylene diamine (TPEN) and measured ECRE in the line-scan mode using a confocal scanner. In the concentration of 0.2 mM TPEN suppressed, rather than increased the frequency of ECRE sometimes to the point that no events were detectable. To determine whether this effect was due to chelating calcium or to a direct inhibition of ryanodine receptors (RyR1) by TPEN, the effects of the drug were studied on isolated RyR1-s incorporated into planar lipid bilayers. TPEN increased channel activity (open probability) at negative (cis compared to trans) holding potentials in a concentration and calcium dependent manner. In contrast, at positive holding potentials an inhibition was observed. Channel inhibition exhibited a voltage dependence resulting in a full inhibition at and above 40 mV. On the other hand, no potential dependence was observed when negative holding potentials were applied. In addition, the activity of the calcium pump was also inhibited by TPEN with a Kd of 639?44 ?M and a Hill coefficient of 0.87 ? 0.06. It is concluded that chelation alone of intra SR calcium will not increase ECRE frequency.This work was supported by OTKA T034894, T037727 and ETT 250/2003.
Tárgyszavak:	Természettudományok Biológiai tudományok idézhető absztrakt calcium release
Megjelenés:	Biophysical Journal. - 88 : Supplement 2 (2005), p. 636a. -
További szerzők:	Simut, Cecilia Almássy János (1981-) (élettanász, biológus, angol-magyar szakfordító) Jung, Carole Niggli, Ernst Jóna István (1948-) (élettanász, fizikus)
Pályázati támogatás:	T037727 OTKA
Internet cím:	Szerző által megadott URL Intézményi repozitóriumban (DEA) tárolt változat
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