The characteristics of K+-evoked outflow of [3H]d-aspartate, a glutamate release marker, were systematically investigated in the rat hippocampus, using 35 mM K+-evoked [3H]noradrenaline outflow as a reference. Elevation of external K+-concentrations increased [3H]d-aspartate outflow in a concentration-dependent manner both in slices and synaptosomes. In the absence of external Ca2+, K+-evoked [3H]d-aspartate outflow was decreased by approx 60% in synaptosomes and 80% in slices. However, elimination of external Ca2+ in the presence of 2 mM EGTA significantly reduced only 100 mM K+-evoked outflow, both in slices and synaptosomes. In the absence of external Ca2+, 35 mM K+-evoked [3H]noradrenaline outflow was abolished even when EGTA was present in the solution. Furthermore, the Ca2+-channel blockers omega-conotoxin (10 nM) and nifedipine (0.5 μM) did not significantly reduce K+-evoked [3H]d-aspartate outflow; [3H]noradrenaline outflow, however, was reduced by more than one third by omega-...
Characterization of K+-evoked [3H]d-aspartate outflow in the rat hippocampus in vitro
SIMONATO, Michele;BREGOLA, Gianni;BIANCHI, Clementina;BEANI, Lorenzo
1993
Abstract
The characteristics of K+-evoked outflow of [3H]d-aspartate, a glutamate release marker, were systematically investigated in the rat hippocampus, using 35 mM K+-evoked [3H]noradrenaline outflow as a reference. Elevation of external K+-concentrations increased [3H]d-aspartate outflow in a concentration-dependent manner both in slices and synaptosomes. In the absence of external Ca2+, K+-evoked [3H]d-aspartate outflow was decreased by approx 60% in synaptosomes and 80% in slices. However, elimination of external Ca2+ in the presence of 2 mM EGTA significantly reduced only 100 mM K+-evoked outflow, both in slices and synaptosomes. In the absence of external Ca2+, 35 mM K+-evoked [3H]noradrenaline outflow was abolished even when EGTA was present in the solution. Furthermore, the Ca2+-channel blockers omega-conotoxin (10 nM) and nifedipine (0.5 μM) did not significantly reduce K+-evoked [3H]d-aspartate outflow; [3H]noradrenaline outflow, however, was reduced by more than one third by omega-...I documenti in SFERA sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
