| Popis |
Background: The Y4734C variant in the ryanodine receptor type 2 (RYR2) was found in a female patient with diagnosed catecholaminergic polymorphic ventricular tachycardia. The variant hasn´t been functionally tested before. The cardiomyocytes derived from human induced pluripotent stem cells (hiPSC-CM) of the patient (CPVT) and her healthy son (WT) were prepared to elucidate the proarrhythmic potential of the variant. It was previously shown that sex hormones influence the electrophysiological properties of hiPSC-CM, thus, we decided to test their effect on the hiPSC-CM with the Y4734C variant. Here we bring data showing the spontaneous electrical activity of the hiPSC-CM and its changes under arrhythmogenic conditions. Methods: The spontaneous electrical activity of hiPSC-CM was recorded (i.) in medium (RPMI 1640+B27) before and 48 h after adding hormones (ß-estradiol 1 nM, ESTR, or dihydrotestosterone 3 nM, DHT), (ii.) in control conditions (Tyrode solution 5 mM K+, t37°C), and (iii.) under cumulatively added hypokalemia (3K+), hyperthermia (t40°C), and ß-adrenergic stimulation (0.5 µM ISO) using the multielectrode array technique. The cycle length (CL) and field potential duration (FPD) were evaluated; Fridericia´s formula was used to correct FPD (FPDc). The short-term variability of CL (STVCL) was calculated using the Origin2025 software. The data for CL, FPD, and FPDc are presented as mean±SEM and for STVCL as the median±interquartile range of n samples (nWT=5; nCPVT=8; nCPVT/DHT=10; nCPVT/ESTR=9), The parametric tests were used for CL, FPD, and FPDc, but non-parametric tests were used for STVCL due to non-normal data distribution; P?0.05 was considered statistically significant. Results: There were no significant differences in CL, STVCL, FPD, or FPDc between CPVT groups before and after the application of sex hormones in the medium. In control conditions, WT (0.76±0.06s) showed a significantly shorter CL than CPVT (1.30±0.19s). There were no significant differences among the groups in FPD. However, there was significantly longer FPDc in CPVTESTR (170.5±12.3ms) than in CPVT (139.9±7.1ms). STVCL was significantly higher in CPVT (42.0±120.5ms) than in WT (2.1±0.4ms). There were no significant differences between CPVT groups in STVCL in control conditions. Concerning arrhythmogenic conditions, the accumulation of 3K+ and t40°C caused a significant increment in STVCL in all groups (WT to 8.1±12.8ms, CPVT to 105.4±1891.6ms, CPVTDHT from 352.8±589.3 to 3077.0±3117.5ms, CPVTESTR from 216.0±249.5 to 2373.3±1918.1ms). Furthermore, WT had significantly lower STVCL than CPVT in 3K+ and t40°C, in addition, CPVTDHT and CPVTESTR had significantly higher STVCL than CPVT. Conclusions: CPVT had longer CL and higher beating variability than WT. In CPVT, application of ESTR caused longer FPDc and both DHT and ESTR caused an increment in the beating variability during 3K+ and t40°C. Generally, the results imply a larger arrhythmogenic propensity in CPVT hiPSC-CM.
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