Impact of I_SK Voltage and Ca²⁺/Mg²⁺-Dependent Rectification on Cardiac Repolarization.

ABSTRACT: Cardiac small conductance Ca²⁺-activated K⁺ (SK) channels are activated solely by Ca²⁺, but the SK current (I_SK) is inwardly rectified. However, the impact of inward rectification in shaping action potentials (APs) in ventricular cardiomyocytes under β-adrenergic stimulation or in disease states remains undefined. Two processes underlie this inward rectification: an intrinsic rectification caused by an electrostatic energy barrier from positively charged amino acids at the inner pore and a voltage-dependent Ca²⁺/Mg²⁺ block. Thus, Ca²⁺ has a biphasic effect on I_SK, activating at low [Ca²⁺] yet inhibiting I_SK at high [Ca²⁺]. We examined the effect of I_SK rectifi

SUBMITTER: Bronk P 

PROVIDER: S-EPMC7399499 | biostudies-literature | 2020 Aug

REPOSITORIES: biostudies-literature