Abstract
The ionic mechanism of the membrane permeability changes caused by l-glutamate in hippocampal neurons prepared from 17- to 19-day-old fetal rat in dispersed cell cultures was studied with the whole-cell variation of the patch electrode voltage-clamp technique. The cultured hippocampal neurons became sensitive to glutamate 7 days after plating, and thereafter the sensitivity gradually increased. The conductance increase caused by glutamate was voltage-sensitive, decreasing with membrane hyperpolarization at potentials more negative than -40 mV. The relative permeability of glutamate-activated channels to alkali metal and alkaline earth cations was estimated by reversal potential measurements. The alkali metal cations, Li+, Na+, K+, Rb+ and Cs+ were permeant to the glutamate channels, and the selectively among them was weak. The alkaline earth cations, Ca2+, Sr2+ and Ba2+ were more permeant than the alkali metals. The permeability ratios of these divalent cations relative to Na+ were 2.4 (Ca2+), 2.4 (Sr2+) and 2.8 (Ba2+), respectively. Mg2+ was much less permeant and the permeability ratio (PMg/PNa) was only 0.1. Anion conductance made no contribution to the glutamate-induced current. Functional implications of the glutamate-induced increase in Ca2+-influx were discussed.
Original language | English |
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Pages (from-to) | 85-94 |
Number of pages | 10 |
Journal | Brain Research |
Volume | 443 |
Issue number | 1-2 |
DOIs | |
Publication status | Published - 1988 Mar 8 |
Externally published | Yes |
Keywords
- Alkali metal cation
- Calcium
- Cultured hippocampal neuron
- Magnesium
- Membrane permeability
- Whole-cell voltage-clamp
- l-Glutamate
ASJC Scopus subject areas
- Neuroscience(all)
- Molecular Biology
- Clinical Neurology
- Developmental Biology