Cardiac Arrhythmias - New Considerations

Abstract

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L-type channel inactivation balances the increased peak calcium current due to absence of Rad in cardiomyocytes

“…The L-type calcium channel (LTCC) is a heteromultimeric protein complex that governs the entry of calcium necessary to initiate a contraction, and the LTCC contributes to the cardiac action potential (AP) plateau phase ( Breijo-Marquez, 2012 ). Cardiomyocyte LTCC activity is tightly regulated to prevent calcium overload ( Bers, 2002 ) and afterdepolarizations of the AP ( January et al, 1988 ; January and Riddle, 1989 ).…”

“…The decay kinetics of I Ca,L is a key point of control. Inactivation of the LTCC occurs by two distinct mechanisms: calcium-dependent inactivation (CDI) and voltage-dependent inactivation (VDI; Breijo-Marquez, 2012 ; Pelzer et al, 1990 ). The early peak of L-type calcium current (I Ca,L ) triggers CICR from the SR that is essential for excitation–contraction coupling; calcium released from the SR or entering through the channel itself binds to calmodulin (CaM) prebound to the EF hand of the C terminus of the main pore-forming subunit of the LTCC ( Zühlke et al, 1999 ).…”