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Cell and Developmental Biology

2002

Hyposmolarity

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Full-Text Articles in Life Sciences

Osmosensitive Release Of Neurotransmitter Amino Acids: Relevance And Mechanisms, Herminia Pasantes-Morales, Rodrigo Franco, Lenin Ochoa, Benito Ordaz Feb 2002

Osmosensitive Release Of Neurotransmitter Amino Acids: Relevance And Mechanisms, Herminia Pasantes-Morales, Rodrigo Franco, Lenin Ochoa, Benito Ordaz

School of Veterinary and Biomedical Sciences: Faculty Publications

Hyposmolarity activates amino acid efflux as part of the corrective volume process in a variety of cells. This review discusses the mechanism of amino acid release in brain cells preparations. Results present evidence of substantial differences between the efflux of taurine and that of GABA and glu-tamate, which besides a possible role as osmolytes, have a main function as synaptic transmitters. The differences found concern the efflux time course, the sensitivity to Cl channel blockers, the modulation by tyrosine kinases, the influence of PKC and the effect of cytoskeleton disruptive agents. While taurine efflux features fit well with the …


Influence Of Protein Tyrosine Kinases On Cell Volume Change-Induced Taurine Release, Herminia Pasantes-Morales, Rodrigo Franco Jan 2002

Influence Of Protein Tyrosine Kinases On Cell Volume Change-Induced Taurine Release, Herminia Pasantes-Morales, Rodrigo Franco

School of Veterinary and Biomedical Sciences: Faculty Publications

Taurine efflux occurs in association with cell swelling in both hyposmotic and isosmotic conditions and during cell shrinkage in apoptotic death. Release occurs through a leak pathway, is largely Ca2+-independent and is sensitive to Cl channel blockers. Taurine efflux elicited by hyposmolarity is reduced or suppressed by tyrosine kinase blockers and increased by tyrosine phosphatase inhibitors. The specific kinases involved are still unknown and may be different in the various cell types. Non-receptor and scr-related protein kinases have been identified in some cells as elements that directly phosphorylate the taurine efflux pathway. Possible tyrosine kinase targets are …


Mechanisms Counteracting Swelling In Brain Cells During Hyponatremia, Herminia Pasantes-Morales, Rodrigo Franco, Benito Ordaz, Lenin D. Ochoa Jan 2002

Mechanisms Counteracting Swelling In Brain Cells During Hyponatremia, Herminia Pasantes-Morales, Rodrigo Franco, Benito Ordaz, Lenin D. Ochoa

School of Veterinary and Biomedical Sciences: Faculty Publications

Water gain in the brain consequent to hyponatremia is counteracted by mechanisms that initially include a compensatory displacement of liquid from the interstitial space to cerebrospinal fluid and systemic circulation and subsequently an active reduction in cell water accomplished by extrusion of intracellular osmolytes to reach osmotic equilibrium. Potassium (K+), chloride (Cl), amino acids, polyalcohols, and methylamines all contribute to volume regulation, with a major contribution of ions at the early phase and of organic osmolytes at the late phase of the regulatory process. Experimental models in vitro show that osmolyte fluxes occur via leak pathways …