title: Characteristics of taurine release from cerebral cortex slices induced by sodium-deficient media.
abstract: Taurine release from rat cerebral cortex slices as influenced by changes in sodium metabolism has been investigated. Superfusion of the slices with sodium deficient medium enhanced taurine release in a reversible manner. The enhancement was about 6 times greater than that induced by 50 mM potassium. Moreover, elevated potassium concentrations slightly decreased the enhancement produced by sodium-free medium. Omission of calcium ions increased the spontaneous efflux of taurine and diminished, but did not abolish, the release induced either by sodium-free or high-potassium medium. The changes in taurine release in the presence of calcium were parallel to the changes in concomitant calcium uptake. Sodium-deficient medium decreased the potassium content of the slices, indicating inhibition of the Na+, K+-ATPase. In agreement with this result, ouabain greatly increased the spontaneous efflux of taurine and eliminated the stimulation by sodium-free medium. The present results emphasize the importance of the resting-state sodium gradients for neural cells to retain high taurine concentrations. Thus, when the Na+, K+-ATPase activity is inhibited, a decrease in sodium gradients may lead to a redistribution of taurine between cytoplasmic and interstitial spaces. Such a mechanism would allow taurine to act as an unspecific modulator of neural membrane events.
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism; D002540:Cerebral Cortex / Q000502:physiology*; D046508:Culture Techniques; D005110:Extracellular Space / Q000502:physiology; D007473:Ion Channels / Q000502:physiology; D008297:Male; D008564:Membrane Potentials; D011188:Potassium / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains; D012964:Sodium / Q000502:physiology*; D009435:Synaptic Transmission; D013654:Taurine / Q000378:metabolism*
chemical_list: D007473:Ion Channels; D013654:Taurine; D012964:Sodium; D011188:Potassium; D002118:Calcium