1. Probing intracellular potassium dynamics in neurons with the genetically encoded sensor lc-LysM GEPII 1.0 in vitro and in vivo.
- Author
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Groschup B, Calandra GM, Raitmayr C, Shrouder J, Llovera G, Zaki AG, Burgstaller S, Bischof H, Eroglu E, Liesz A, Malli R, Filser S, and Plesnila N
- Subjects
- Animals, Mice, Action Potentials, Cells, Cultured, Fluorescence Resonance Energy Transfer methods, Optogenetics methods, Potassium metabolism, Neurons metabolism, Biosensing Techniques methods
- Abstract
Neuronal activity is accompanied by a net outflow of potassium ions (K
+ ) from the intra- to the extracellular space. While extracellular [K+ ] changes during neuronal activity are well characterized, intracellular dynamics have been less well investigated due to lack of respective probes. In the current study we characterized the FRET-based K+ biosensor lc-LysM GEPII 1.0 for its capacity to measure intracellular [K+ ] changes in primary cultured neurons and in mouse cortical neurons in vivo. We found that lc-LysM GEPII 1.0 can resolve neuronal [K+ ] decreases in vitro during seizure-like and intense optogenetically evoked activity. [K+ ] changes during single action potentials could not be recorded. We confirmed these findings in vivo by expressing lc-LysM GEPII 1.0 in mouse cortical neurons and performing 2-photon fluorescence lifetime imaging. We observed an increase in the fluorescence lifetime of lc-LysM GEPII 1.0 during periinfarct depolarizations, which indicates a decrease in intracellular neuronal [K+ ]. Our findings suggest that lc-LysM GEPII 1.0 can be used to measure large changes in [K+ ] in neurons in vitro and in vivo but requires optimization to resolve smaller changes as observed during single action potentials., (© 2024. The Author(s).)- Published
- 2024
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