Imaging Ca ²⁺ Nanosparks in Heart With a New Targeted Biosensor

Culture and adenoviral infection of sinoatrial node myocytes from adult mice

“…Ca 2ϩ release from the SR is thought to be critical for pacemaker activity in SAMs (5,13,34), and genetically-encoded Ca 2ϩ indicators (GECIs) could provide important new insights into this process. GECIs can be targeted to subcellular microdomains and have yielded much important information about localized Ca 2ϩ signaling in other types of cardiac myocytes (10,11,22,27,36). In a similar manner, tethered FRET-based cAMP sensors could be used to characterize spatio-temporal cAMP signaling associated with different GPCRs and phosphodiesterase isoforms, as has been done in other cardiac myocytes (20,23,30,37,43).…”

Genetically Encoded Ca 2+ Indicators in Cardiac Myocytes

“…76 Based on the fastest version of these indicators (GCaMP6f), C-terminal fusion proteins of tradin1 and junctin, GCaMP6f-T and GCaMP6f-J, respectively, allowed Ca 2+ measurements exclusively in the dyadic cleft. 118 The recorded signals were termed Ca 2+ nanosparks because their calculated volume was ≈50× smaller than that of Ca 2+ sparks. Although the focus of that article 118 was methodology, the peak intensity (F/F o ) of the nanotransients was 7.8-fold higher because of global Ca 2+ elevation.…”

Revealing t-tubules in striated muscle with new optical super-resolution microscopy techniques

“…50 We also underscore the potential utility of SMLM and other optical super-resolution modes in supplementing (diffraction-limited) confocal fluorescence microscopy of calcium micro-and nanodomains (e.g. imaging Ca 2+ sparks with intra-dyadic Ca 2+ sensors 87 ) to correlate functional measurements with the local ultrastructure.…”