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. Author manuscript; available in PMC: 2014 Sep 1.
Published in final edited form as: Nat Genet. 2013 Jul 21;45(9):1044–1049. doi: 10.1038/ng.2712

Figure 3.

Figure 3

Increased conduction velocity and sodium channel availability in the RVOT of adult Hey2+/− mice. (a) Representative optical activation maps from isolated wild-type (WT; n = 12) and Hey2+/− (n = 11) hearts stimulated at the RVOT at a basic cycle length of 120 ms (scale bars, 1 mm). Arrows indicate conduction along the RVOT epicardium through the connection of similar isochrones. Isochrones (0.5-ms intervals) in the RVOT of Hey2+/− hearts are less crowded compared to wild-type isochromes, indicating faster conduction in the RVOT of Hey2+/− hearts (as indicated by increased arrow length). (b) On average, conduction velocity in the RVOT of Hey2+/− hearts was significantly increased compared to that in wild-type hears (*P < 0.05; Student’s t test). Error bars, s.e.m. (c) Representative action potentials measured in adult wild-type (WT; n = 7) and Hey2+/− (n = 11) cardiomyocytes isolated from RVOT. (d) Average action potential characteristics measured at 4 Hz. RVOT cardiomyocytes from Hey2+/− mice showed a significant increase in maximal upstroke velocity (dV/dTmax, a measure of sodium channel availability and a determinant of conduction velocity) and action potential amplitude (APA), indicating increased sodium channel availability (*P < 0.05; **P < 0.01; Student’s t test). Resting membrane potential (RMP), action potential duration at 20% and 50% repolarization (APD20 and APD50, respectively) were not significantly different in wild-type and Hey2+/− mice; action potential duration at 90% repolarization (APD90) was significantly increased in RVOT cardiomyocytes from Hey2+/− mice. Results are expressed as mean ± s.e.m.