单个神经元O2消耗量、细胞内Ca2+浓度和线粒体膜电位的...

单个神经元O2消耗量、细胞内Ca2+浓度和线粒体膜电位的同时记录

Abstract：
In order to determine the sequence of cellular processes in glutamate toxicity, we simultaneously recorded O₂ consumption,cytosolic Ca²⁺ concentration ([Ca²⁺]i), and mitochondrial membrane potential (mDw) in single cortical neurons. Oxygen consumption was measured using an amperometric selfreferencing platinum electrode adjacent to neurons in which [Ca²⁺]i and mDw were monitored with Fluo-4 and TMRE+,respectively, using a spinning disk laser confocal microscope.Excitotoxic doses of glutamate caused an elevation of [Ca²⁺]i followed seconds afterwards by an increase in O₂ consumption which reached a maximum level within 1–5 min. A modest increase in mDw occurred during this time period, and then, shortly before maximalO₂ consumption was reached, themDw, as indicated by TMRE+ fluorescence, dissipated. Maximal O₂ consumption lasted up to 5 min and then declined together with mDw and ATP levels, while [Ca²⁺]i further increased. mDw and [Ca²⁺]i returned to baseline levels when neurons were treated
with an NMDA receptor antagonist shortly after the [Ca²⁺]i increased. Our unprecedented spatial and time resolution revealed that this sequence of events is identical in all neurons, albeit with considerable variability in magnitude and kinetics of changes in O₂ consumption, [Ca²⁺]i, and mDw. The data obtained using this new method are consistent with a model where Ca²⁺ influx causes ATP depletion, despite maximal mitochondrial respiration, minutes after glutamate receptor activation.
Keywords: excitotoxicity, glutamate, oxygen consumption.