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Release of taurine from astrocytes during potassium-evoked swelling

✍ Scribed by Herminia Pasantes-morales; Dr. Arne Schousboe

Publisher: John Wiley and Sons
Year: 1989
Tongue: English
Weight: 630 KB
Volume: 2
Category: Article
ISSN: 0894-1491
DOI: 10.1002/glia.440020105

No coin nor oath required. For personal study only.

✦ Synopsis

Cultured astrocytes superfused with isosmotic solutions containing high concentrations of potassium, i.e., 25,56,75, and 100 mM, showed a proportional increase in cell volume corresponding to 25, 36, 57, and 75% greater than the cell volume in physiological solutions. This volume increase was abolished in low chloride or hypertonic solutions.

The release of 3H-taurine previously accumulated by astrocytes was stimulated by potassium at all concentrations examined. During 4-minute exposure to 25,56,75, or 100 mM of potassium, cells released 13.5,15.6,20.2, or 36.2%, respectively, of the total labeled taurine accumulated during the preloading period. The potassium-stimulated release of 3H-taurine was calcium-independent and insensitive to BaClz and bumetanide. Substitution of chloride by gluconate to concentrations necessary to maintain the K+ X C1product constant abolished the potassium-stimulated release of 3H-taurine. Superfusion with solutions made hypertonic with sucrose also decreased the potassium-elicited efflux of 3H-taurine. In both conditions, the depolarizing effect of potassium measured with 3H-TPP+ was unchanged. High potassium concentrations and hyposmotic solutions released 3H-taurine by a nonadditive mechanism. These results indicate that in cultured astrocytes high concentrations of potassium produce both swelling and depolarization, but only swelling elicits the release of taurine. These observations suggest a n involvement of taurine in cell-volume regulation in astrocytes.

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