Taurine efflux and intracellular pH during astrocyte volume regulation

Advances in Experimental Medicine and Biology
J E OlsonN Munoz

Abstract

Cytotoxic cerebral edema is characterized by enlarged astroglial cells. In tissue culture, osmotically swollen astrocytes return toward normal volume over a period of 15-30 min in a process termed regulatory volume decrease (RVD). RVD is due, in part, to net efflux of taurine and other amino acids. Our objective in these studies was to examine changes in astrocyte intracellular pH (pHi) which may be related to taurine loss during RVD. We hypothesized net efflux of anionic taurine abandons a proton inside the cell, thus lowering pHi. Primary cultures of cerebral astrocytes were prepared from neonatal rats pups and grown on glass coverslips. Confluent cells were loaded at 37 degrees C with the fluorescent pH indicator BCECF. Fluorescence intensity ratios for excitation wavelengths of 440 nm and 494 nm (530 nm emission) were computed every 2 sec. Intensity ratios were calibrated to pHi at the end of each experiment using 140 mM KCl plus 8.6 microM nigericin at pH 7.4. pHi was measured in isoosmotic Hepes-buffered saline (290 mOsm) and then in hypoosmotic Hepes-buffered saline (200 mOsm) in the presence of 0.5 mM amiloride. Some solutions also contained 150 microM niflumic acid (NA). Cellular taurine content was determined in paral...Continue Reading

Citations

Jun 20, 2001·European Journal of Anaesthesiology·J MühlingG Hempelmann
Apr 11, 2000·Acta Anaesthesiologica Scandinavica·J MühlingG Hempelmann
Sep 25, 2003·Physiological Reviews·Mitchell Chesler
Feb 16, 1999·Biochimica Et Biophysica Acta·J E Olson

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