Abstract
We synthesized a water-soluble, long-wavelength K+ sensor, TAC-Red, consisting of triazacryptand coupled to 3,6-bis(dimethylamino)xanthylium, whose fluorescence increased 14-fold at 0–50 mM K+ with K+-to-Na+ selectivity >30. We visualized K+ waves in TAC-Red–stained brain cortex in mice during spreading depression, with velocity 4.4 ± 0.5 mm/min, and K+ release and reuptake half-times (t1/2) of 12 ± 2 and 32 ± 4 s, respectively. Aquaporin-4 (AQP4) deletion slowed K+ reuptake about twofold, suggesting AQP4-dependent K+ uptake by astroglia.
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Acknowledgements
This work was supported by US National Institutes of Health grants EB00415, DK35124, EY13574, HL59198, DK72517 and HL73856, and a Research Development Program grant from the Cystic Fibrosis Foundation.
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Supplementary Video 1
Video of propagating wave of increasing [K+]o. 1 frame/2 seconds; total video: 194 seconds; image width: 2.75 mm. TAC-Red fluorescence intensity encoded in pseudocolor as per legend to Figure 2b. (MOV 2168 kb)
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Padmawar, P., Yao, X., Bloch, O. et al. K+ waves in brain cortex visualized using a long-wavelength K+-sensing fluorescent indicator. Nat Methods 2, 825–827 (2005). https://doi.org/10.1038/nmeth801
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DOI: https://doi.org/10.1038/nmeth801
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