2-Photon excitation fluorescence microscopy enables deeper high-resolution imaging of voltage and Ca(2+) in intact mice, rat, and rabbit hearts
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Updated: May 7, 2026
Optical Mapping of Action Potentials and Calcium Transients in the Mouse Heart
Published on: September 13, 2011
Iffath A Ghouri1, Allen Kelly, Francis L Burton
1Institute of Cardiovascular and Medical Sciences; College of Medical, Veterinary, and Life Sciences, University of Glasgow, Glasgow, G12 8QQ, UK.
Abstract:
We describe a novel two-photon (2P) laser scanning microscopy (2PLSM) protocol that provides ratiometric transmural measurements of membrane voltage (Vm ) via Di-4-ANEPPS in intact mouse, rat and rabbit hearts with subcellular resolution. The same cells were then imaged with Fura-2/AM for intracellular Ca(2+) recordings. Action potentials (APs) were accurately characterized by 2PLSM vs. microelectrodes, albeit fast events (<1 ms) were sub-optimally acquired by 2PLSM due to limited sampling frequencies (2.6 kHz). The slower Ca(2+) transient (CaT) time course (>1ms) could be accurately described by 2PLSM. In conclusion, Vm - and Ca(2+) -sensitive dyes can be 2P excited within the cardiac muscle wall to provide AP and Ca(2+) signals to ∼400 µm.
