Abstract 11948: Flecainide Induces a New Population of Calcium Sparks in Rat Cardiomyocytes

Flecainide has previously been reported to reduce spark amplitude and mass, but increase frequency, in ventricular cardiomyocytes from a Catecholaminergic Polymorphic Ventricular Tachycardia (CPVT) mouse model. We studied the therapeutic potential of flecainide to suppress catecholamine-induced Ca2+ sparks in healthy cardiomyocytes. Confocal microscopy of isolated intact adult rat ventricular cardiomyocytes treated with 30nM isoprenaline was used to record Ca2+ sparks, transients and SR Ca2+ load in the presence (FLEC) or absence (CTRL) of 5µM flecainide loaded for 5 mins. In concordance with previous results flecainide reduced Ca2+ transient amplitude consistent with its known negatively inotropic effects (CTRL F/F0 8.7±0.4, FLEC 7.8 ± 0.4, p=0.0003, n=24 cells) despite SR load being similar between the two groups. With respect to mean spark parameters (n=380 sparks from 31 cells), there were no significant differences in frequency, amplitude, spark mass or spark-mediated SR leak (mass x frequency). Howe...