Time-Resolved Imaging Reveals Heterogeneous Landscapes of Nanomolar Ca(2+) in Neurons and Astroglia.
Maintaining low intracellular calcium is essential to the functioning of brain cells, yet the phenomenology and mechanisms involved remain an enigma. We have advanced a two-photon excitation time-resolved imaging technique, which exploits high sensitivity of the OGB-1 fluorescence lifetime to nanomolar Ca(2+) concentration ([Ca(2+)]) and enables a high data acquisition rate in situ. The [Ca(2+)] readout is not affected by dye concentration, light scattering, photobleaching, micro-viscosity, temperature, or the main known concomitants of cellular activity. In quiescent tissue, standard whole-cell configuration has little effect on resting [Ca(2+)] inside neuronal dendrites or inside astroglia dye-filled via gap junctions. Mapping basal [Ca(2+)] in neurons and astrocytes with submicron resolution unveils heterogeneous concentration landscapes that depend on age and preceding activity. The rich information content represented by such landscapes in acute slices and in vivo promises to unveil the hitherto unexplored, potentially fundamental aspects of brain cell physiology.
UCL Institute of Neurology, University College London, Queen Square, London WC1N 3BG, UK. Electronic address: k.zheng@ucl.ac.uk.
Kaiyu
K
Zheng
UCL Institute of Neurology, University College London, Queen Square, London WC1N 3BG, UK.
Lucie
L
Bard
UCL Institute of Neurology, University College London, Queen Square, London WC1N 3BG, UK.
James P
JP
Reynolds
UCL Institute of Neurology, University College London, Queen Square, London WC1N 3BG, UK.
Claire
C
King
UCL Institute of Neurology, University College London, Queen Square, London WC1N 3BG, UK.
Thomas P
TP
Jensen
Department of Neuroscience, Physiology and Pharmacology, University College London, Gower Street, London WC1E 6BT, UK.
Alexander V
AV
Gourine
UCL Institute of Neurology, University College London, Queen Square, London WC1N 3BG, UK. Electronic address: d.rusakov@ucl.ac.uk.
Dmitri A
DA
Rusakov
D000818:Animals; D001253:Astrocytes / Q000737:chemistry*; D002118:Calcium / Q000032:analysis*; D008297:Male; D036641:Microscopy, Fluorescence, Multiphoton / Q000379:methods*; D036103:Nanotechnology / Q000379:methods*; D009474:Neurons / Q000737:chemistry*; D009924:Organ Culture Techniques; D051381:Rats; D017207:Rats, Sprague-Dawley; D059008:Time-Lapse Imaging / Q000379:methods*
D002118:Calcium