The role of sulfhydryl groups in d-aspartate and rubidium release from neonatal rat primary astrocyte cultures

M. Aschner, K. J. Mullaney, M. N. Fehm, D. Vitarella, D. E. Wagoner, H. K. Kimelberg

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Abstract

We have recently demonstrated that both methylmercury (MeHg) and mercuric chloride (MC) induce d-aspartate release from neonatal rat primary astrocyte cultures maintained in isotonic conditions [1,3,21,22]. In the present study, we compare several other sulfhydryl-(-SH) selective alkylating reagents [methyl methanethiosulfonate (MMTS), N-ehtylmaleimide (NEM), and iodoacetamide (IA)] in isotonic, as well as hypotonic conditions to discern the functional importance of -SH groups in [3H]d-aspartate and 86rubidium (86Rb) release from astrocytes. Treatment of astrocytes (5 min) in isotonic buffer with the hydrophobic reagent NEM (10 μM) caused a marked increase in 86Rb release but had no effect of [3H]d-aspartate release. Neither IA-, nor MMTS-treatment (both at 10 μM) induced increase in [3H]d-aspartate of 86Rb release in isotonic buffer. In hypotonic condition (-50 mM Na+), astrocytes were most sensitive to MC exposure (5 μM), exhibiting an increase in both [3H]d-aspartate and 86Rb efflux. The hydrophobic compounds MMTS and NEM, and the hydrophilic -SH modifying reagent, IA, attenuated the hypotonic-induced efflux of [3H]d-aspartate, in the absence of an effect of 86Rb release. These observations are consistent with a critical role for -SH groups both in basal (i.e. isotonic) and hypotonic-induced release of d-aspartate and Rb from astrocytes. Lack of uniformity of these effects may be attributed to site-specificity, related to the physicochemical properties of these -SH alkylating reagents.

Original languageEnglish (US)
Pages (from-to)16-23
Number of pages8
JournalBrain Research
Volume648
Issue number1
DOIs
Publication statusPublished - Jun 13 1994
Externally publishedYes

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Keywords

  • -SH group
  • Astrocyte
  • Hypotonicity
  • Regulatory volume decrease
  • Rubidium
  • d-Aspartate

ASJC Scopus subject areas

  • Neuroscience(all)
  • Molecular Biology
  • Clinical Neurology
  • Developmental Biology

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