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Potassium and Taurine Release Are Highly Correlated with Regulatory Volume Decrease in Neonatal Primary Rat Astrocyte Cultures
Author(s) -
Vitarella Domenico,
DiRisio Darryl J.,
Kimelberg Harold K.,
Aschner Michael
Publication year - 1994
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1046/j.1471-4159.1994.63031143.x
Subject(s) - taurine , trifluoperazine , calcium , extracellular , chemistry , glutamate receptor , bapta , biochemistry , extracellular fluid , calmodulin , pharmacology , medicine , biology , amino acid , receptor , organic chemistry
Neonatal rat primary astrocyte cultures were swollen by exposure to hypotonic buffer. Using an electrical impedance method for determination of cell volume coupled with on‐line measurements of efflux of radioactive ions or amino acids, we have investigated the role of K + (using 86 Rb), taurine, and d ‐aspartate (an analogue of glutamate) in regulatory volume decrease (RVD). Addition of 1 m M quinine, 10 µ M nimodipine, 100 µ M BAPTA‐AM, 10 µ M trifluoperazine, or a calcium‐free buffer significantly ( p < 0.0001) inhibited RVD. This was accompanied by inhibition of 86 Rb release but an increase in d ‐[ 3 H]‐aspartate release, which was proportional to the degree to which RVD was inhibited. These results support a regulatory role for calcium in RVD and show that inhibition of calcium entry from the extracellular fluid, intracellular calcium sequestration, inhibition of calcium‐activated K + channels, and inhibition of calmodulin all inhibit RVD. Because d ‐[ 3 H]aspartate efflux profiles increase as RVD is inhibited, it is unlikely that d ‐aspartate release is a main determinant of RVD. In contrast, [ 3 H]taurine release was increased by 1 m M quinine and inhibited by 10 µ M trifluoperazine. The net release of K + and taurine is highly correlated with the degree of RVD, implicating a regulatory role for both K + and taurine release in RVD.