부산대학교 도서관

Summary: Astroglia regulate neurovascular coupling while engaging in signal exchange with neurons. The underlying cellular machinery is thought to rely on astrocytic Ca2+ signals, but what controls their amplitude and waveform is poorly understood. Here, we employ time-resolved two-photon excitation fluorescence imaging in acute hippocampal slices and in cortex in vivo to find that resting [Ca2+] predicts the scale (amplitude) and the maximum (peak) of astroglial Ca2+ elevations. We bidirectionally manipulate resting [Ca2+] by uncaging intracellular Ca2+ or Ca2+ buffers and use ratiometric imaging of a genetically encoded Ca2+ indicator to establish that alterations in resting [Ca2+] change co-directionally the peak level and anti-directionally the amplitude of local Ca2+ transients. This relationship holds for spontaneous and for induced (for instance by locomotion) Ca2+ signals. Our findings uncover a basic generic rule of Ca2+ signal formation in astrocytes, thus also associating the resting Ca2+ level with the physiological “excitability” state of astroglia. : King et al. show that, in brain astroglia, a high resting [Ca2+] increases the maximum level but decreases the amplitude of local Ca2+ signals. This fundamental relationship holds over a wide range of preparations, ranging from hippocampal astrocytes in acute slices to locomotion-associated Ca2+ signals in the awake animal. Keywords: brain, astrocytes, calcium signalling, mechanism, calcium stores, fluorescence microscopy, quantitative, hippocampus, cortex, in vivo, locomotion