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Titolo:
Calcium dynamics and buffering in motoneurones of the mouse spinal cord
Autore:
Palecek, J; Lips, MB; Keller, BU;
Indirizzi:
Univ Gottingen, Zentrum Physiol & Pathophysiol, D-37073 Gottingen, GermanyUniv Gottingen Gottingen Germany D-37073 iol, D-37073 Gottingen, Germany Acad Sci Czech Republ, Inst Physiol, CR-14220 Prague 4, Czech Republic Acad Sci Czech Republ Prague Czech Republic 4 0 Prague 4, Czech Republic
Titolo Testata:
JOURNAL OF PHYSIOLOGY-LONDON
fascicolo: 2, volume: 520, anno: 1999,
pagine: 485 - 502
SICI:
0022-3751(19991015)520:2<485:CDABIM>2.0.ZU;2-3
Fonte:
ISI
Lingua:
ENG
Soggetto:
AMYOTROPHIC-LATERAL-SCLEROSIS; CENTRAL-NERVOUS-SYSTEM; MOTOR-NEURON TOXICITY; BINDING PROTEINS; GRANULE CELLS; CA2+ CHANNELS; NEONATAL RAT; CURRENTS; NUCLEUS; INACTIVATION;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Life Sciences
Citazioni:
50
Recensione:
Indirizzi per estratti:
Indirizzo: Keller, BU Univ Gottingen, Zentrum Physiol & Pathophysiol, Humboldtallee 23, D-37073 Gottingen, Germany Univ Gottingen Humboldtallee 23 Gottingen Germany D-37073 many
Citazione:
J. Palecek et al., "Calcium dynamics and buffering in motoneurones of the mouse spinal cord", J PHYSL LON, 520(2), 1999, pp. 485-502

Abstract

1. A quantitative analysis of endogenous calcium homeostasis was performedon 65 motoneurones in slices of the lumbar spinal cord from 2- to 8-day-old mice by simultaneous patch-clamp and microfluorometric calcium measurements.2. Somatic calcium concentrations were monitored with a temporal resolution in the millisecond time domain. Measurements were performed by using a monochromator for excitation and a photomultiplier detection system.3. Somatic calcium signalling was investigated during defined voltage-clamp protocols. Calcium responses were observed for membrane depolarizations positive to -50 mV. A linear relation between depolarization time and free calcium concentrations ([Ca2+](i)) indicated that voltage-dependent calcium influx dominated the response.4. Endogenous calcium homeostasis was quantified by using the 'added buffer' approach. In the presence of fura-2 and mag-fura-5, calcium transients decayed according to a monoexponential function. Decay-time constants showeda linear dependence on dye concentration and the extrapolated constant in the absence of indicator dye was 371 +/- 120 ms (n = 13 cells, 21 degrees C).5. For moderate elevations (< 1 mu M), recovery kinetics of depolarization-induced calcium transients were characterized by a calcium-independent, 'effective' extrusion rate gamma = 140 +/- 47 s(-1) (n = 13 cells, 21 degreesC).6. The endogenous calcium binding ratio for fixed buffers in spinal motoneurones was kappa(B)' = 50 +/- 17 (n = 13 cells), indicating that less than 2% of cytosolic calcium ions contributed to [Ca2+](i).7. Endogenous binding ratios in spinal motoneurones were small compared tothose found in hippocampal or cerebellar Purkinje neurones. From a functional perspective, they provided motoneurones with rapid dynamics of cytosolic [Ca2+](i) for a given set of influx, extrusion and uptake mechanisms.8. With respect to pathophysiological conditions, our measurements are in agreement with a model where the selective vulnerability of spinal motoneurones during excitotoxic conditions and motoneurone disease partially results from low endogenous calcium buffering.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 14/07/20 alle ore 03:45:11