Small Conductance Calcium-Activated Potassium Current is Important in Transmural Repolarization of Failing XXXX Ventricles.

@entity1 @entity3656 @entity3529 @entity31858 @entity34072 @entity9690 @entity141
BACKGROUND: -The transmural distribution of apamin-sensitive small conductance @entity141 -activated @entity3529 ( @entity31858 ) current (IKAS) in failing @entity1 ventricles remains unclear. METHODS AND RESULTS: -We optically mapped left ventricular wedge preparations from 12 failing native hearts and 2 rejected cardiac allografts explanted during transplant surgery. We determined transmural action potential duration (APD) before and after 100 nM apamin administration in all wedges and after sequential administration of apamin, @entity34072 and @entity9690 in 4 wedges. Apamin prolonged APD from 363 ms [95% confidence interval (CI), 341 to 385] to 409 [CI, 385 to 434] (p<0.001) in all hearts, and reduced the transmural conduction velocity from 36 cm/s [CI, 30 to 42] to 32 cm/s [CI, 27 to 37] (p=0.001) in 12 native failing hearts at 1000 ms @entity3656 ( @entity3656 ). The percent APD prolongation is negatively correlated with baseline APD and positively correlated with @entity3656 . Only one wedge had M-cell islands. The percentages of APD prolongation in the last 4 hearts at 2000 ms @entity3656 after apamin, @entity34072 and @entity9690 were 9.1% [CI, 3.9 to 14.2], 17.3% [CI, 3.1 to 31.5] and 35.9% [CI, 15.7 to 56.1], respectively. Immunohistochemical staining of subtype 2 of @entity31858 ( @entity31858 ) protein showed increased expression in intercalated discs of myocytes. CONCLUSIONS: - @entity31858 current is important in the transmural repolarization in failing @entity1 ventricles. The magnitude of IKAS is positively correlated with the @entity3656 , but negatively correlated with APD when @entity3656 is fixed. There is abundant @entity31858 protein in the intercalated discs of myocytes.
