TY - JOUR
T1 - Efflux of osmolyte amino acids during isovolumic regulation in hippocampal slices
AU - Franco, Rodrigo
AU - Quesada, Octavio
AU - Pasantes-Morales, Herminia
PY - 2000/9/15
Y1 - 2000/9/15
N2 - The efflux of potassium (K+) and amino acids from hippocampal slices was measured after sudden exposure to 10% (270 mOsm), 25% (225 mOsm) or 50% (150 mOsm) hyposmotic solutions or after gradual decrease (-2.5 mOsm/min) in external osmolarity. In slices suddenly exposed to 50% hyposmotic solutions, swelling was followed by partial (74%) cell volume recovery, suggesting regulatory volume decrease (RVD). With gradual hyposmotic changes, no increase in cell water content was observed even when the solution at the end of the experiment was 50% hyposmotic, showing the occurrence of isovolumic regulation (IVR). The gradual decrease in osmolarity elicited the efflux of 3H-taurine with a threshold at -5 mOsm and D-[3H]aspartate (as marker for glutamate) and at -20 mOsm for [3H]GABA. The efflux rate of [3H]taurine was always notably higher than those of [3H]GABA and D-[3H]aspartate, with a maximal increase over the isosmotic efflux of about 7-fold for [3H]taurine and 3- and 2-fold for [3H]GABA and D-[3H]aspartate, respectively. The amino acid content in slices exposed to 50% hyposmotic solutions (abrupt change) during 20 min decreased by 50.6% and 62.6% (gradual change). Taurine and glutamate showed the largest decrease. An enhancement in 86Rb efflux and a corresponding decrease in K+ tissue content was seen in association with RVD but not with IVR. These results demonstrate the contribution of amino acids to IVR and indicate their involvement in this mechanism of cell volume control. (C) 2000 Wiley-Liss, Inc.
AB - The efflux of potassium (K+) and amino acids from hippocampal slices was measured after sudden exposure to 10% (270 mOsm), 25% (225 mOsm) or 50% (150 mOsm) hyposmotic solutions or after gradual decrease (-2.5 mOsm/min) in external osmolarity. In slices suddenly exposed to 50% hyposmotic solutions, swelling was followed by partial (74%) cell volume recovery, suggesting regulatory volume decrease (RVD). With gradual hyposmotic changes, no increase in cell water content was observed even when the solution at the end of the experiment was 50% hyposmotic, showing the occurrence of isovolumic regulation (IVR). The gradual decrease in osmolarity elicited the efflux of 3H-taurine with a threshold at -5 mOsm and D-[3H]aspartate (as marker for glutamate) and at -20 mOsm for [3H]GABA. The efflux rate of [3H]taurine was always notably higher than those of [3H]GABA and D-[3H]aspartate, with a maximal increase over the isosmotic efflux of about 7-fold for [3H]taurine and 3- and 2-fold for [3H]GABA and D-[3H]aspartate, respectively. The amino acid content in slices exposed to 50% hyposmotic solutions (abrupt change) during 20 min decreased by 50.6% and 62.6% (gradual change). Taurine and glutamate showed the largest decrease. An enhancement in 86Rb efflux and a corresponding decrease in K+ tissue content was seen in association with RVD but not with IVR. These results demonstrate the contribution of amino acids to IVR and indicate their involvement in this mechanism of cell volume control. (C) 2000 Wiley-Liss, Inc.
KW - Cell swelling
KW - Hyposmolarity
KW - K efflux
KW - Regulatory volume decrease
KW - Taurine
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U2 - 10.1002/1097-4547(20000915)61:6<701::AID-JNR14>3.0.CO;2-T
DO - 10.1002/1097-4547(20000915)61:6<701::AID-JNR14>3.0.CO;2-T
M3 - Article
C2 - 10972967
AN - SCOPUS:0034666576
SN - 0360-4012
VL - 61
SP - 701
EP - 711
JO - Journal of Neuroscience Research
JF - Journal of Neuroscience Research
IS - 6
ER -