Characterization of the Volume-Activated Taurine Pathway in Cultured Cerebellar Granule Neurons
Early studies on the mechanism of cell taurine transport have consistently identified a component of taurine uptake which is nonsaturable, energy-independent and clearly corresponding to a diffusional mechanism. For long time this component was normally discarded in all studies of taurine uptake in order to obtain the saturable curves of the energy-dependent, high affinity component, which was associated with a presumed neurotransmitter function for taurine. The recent studies on a role for taurine as an osmolyte have praised the diffusional component of the transport system as it has been identified as the mechanism allowing a rapid extrusion of the amino acid to regulate, together with other osmolytes, the cell water content. The occurrence and features of the two components of the taurine transport system fit very adequately this osmolyte role: a diffusional, rapid release of intracellular pools corrects almost immediately an excess of cell water and after this regulatory function, the intracellular taurine pools are replenished by the energy-dependent, high affinity component, which is able to accumulate taurine against large concentration gradients.
KeywordsAnion Channel Regulatory Volume Decrease Niflumic Acid Cell Volume Regulation Taurine Transport
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