Journal article
Effects of glucose deprivation on NMDA-induced current and intracellular Ca2+ in rat substantia nigra neurons
Journal of neurophysiology, Vol.75(2), pp.740-749
02/1996
DOI: 10.1152/jn.1996.75.2.740
PMID: 8714649
Abstract
1. The effects of glucose deprivation on N-methyl-D-asparate (NMDA)-induced current (INMDA) and the intracellular free Ca2+ concentration ([Ca2+]i) in the acutely dissociated rat substantia nigra neurons were investigated using the nystatin-perforated patch-clamp technique under voltage clamp and the microfluometry with a fluorescent probe, Indo-1. 2. Application of NMDA induced a peak and a successive steady-state inward current, and an outward current immediately after washout at a holding potential of -40 mV. The amplitudes of the three current components of INMDA were increased by increasing the concentrations of NMDA with half-maximum concentrations (EC50s) of 1.1 x 10(-4) M, 1.2 x 10(-4) M, and 1.6 x 10(-4) M, respectively. 3. The reversal potentials of the peak inward and outward currents were -4 +/- 3 (SE) mV and -76 +/- 2 mV, respectively. The latter was close to the theoretical K+ equilibrium potential (-82 mV). 4. The outward current was potentiated by increase in extracellular Ca2+ concentration and was blocked by Cs+ internal solution and suppressed by 5 x 10(-3) M tetraethylammonium chloride and 10(-7) M charybdotoxin, indicating that it was Ca(2+)-activated K+ current. 5. Application of NMDA increased [Ca2+]i in a concentration-dependent manner with an EC50 of 3.9 x 10(-5) M. 6. Depriving the external solution of glucose induced a slowly developing outward current and increased the basal level of [Ca2+]i. It also prolonged the NMDA-induced outward current without affecting the peak inward current, and prolonged the NMDA-induced increase in [Ca2+]i without changing the peak [Ca2+]i. 7. These findings suggest that the deprivation of glucose did not affect the NMDA-induced influx of Ca2+ into the cells, but it inhibited Ca2+ clearance by affecting the efflux of Ca2+ to the extracellular space, reuptake into the intracellular Ca2+ stores, and/or active extrusion from intracellular stores.
Details
- Title: Subtitle
- Effects of glucose deprivation on NMDA-induced current and intracellular Ca2+ in rat substantia nigra neurons
- Creators
- Y Nakashima - Department of Anesthesiology, Kyushu University, Fukuoka, JapanH IshibashiN HarataN Akaike
- Resource Type
- Journal article
- Publication Details
- Journal of neurophysiology, Vol.75(2), pp.740-749
- Publisher
- United States
- DOI
- 10.1152/jn.1996.75.2.740
- PMID
- 8714649
- ISSN
- 0022-3077
- eISSN
- 1522-1598
- Language
- English
- Date published
- 02/1996
- Academic Unit
- Molecular Physiology and Biophysics
- Record Identifier
- 9984025686402771
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