Optical Recording of Action Potentials in Human Induced Pluripotent Stem Cell-Derived Cardiac Single Cells and Monolayers Generated from Long QT Syndrome Type 1 Patients

Figure 3

AP measurements of single cells using a membrane potential dye. (a) Examples of AP waves from control (409B2) measured by the dye. ROIs (1)–(5) are ventricular type. ROI (5) (green wave) shows long APD. (b) Examples of AP waves from LQT1B1. ROIs (1)–(4) are ventricular type with long APD. ROI (4) (purple wave) shows EADs. ROI (5) (green wave) is nodal type. (c) Proportion of subtypes in 3 control- and 3 LQT1-iPSC-CMs: 201B7 (), 409B2 (), 692D2 (), LQT1A1 (), LQT1B1 (), and LQT1C1 (). Ventricular-type cells predominate in all six lines. (d) Representative EADs in a ventricular-type cell from LQT1B1. The EADs were defined as over 20% of the AP amplitude. Arrows show EADs. (e) Occurrence ratio of EADs in ventricular cardiomyocytes from the six lines. The number of ventricular cells was used as the denominator; .

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