HERG duration

It is evident from the literature that there is variance in the IC50 values in cloned hERG channels expressed in native mammalian myocytes and in clonaUy derived mammalian cell lines (Kirsch et al. 2004). Clearly, both temperature and pulse (duration and frequency) patterns can influence the inhibitory... 

Multielectrode array (MEA) Field potential duration (FPD) taken from hiPSC-CMs in vitro correlates with the QT interval in an ECG (Fig. 9.5). FPD was prolonged by I /hERG blockers, whereas it was shortened by an 1 blocker, indicating that these ion current components contribute to FPD in hiPSC-CMs (Braam etal., 2013 Harris et al., 2013 Navarrete et al., 2013). 

Cardiac sodium channel (NaVl.5) blockers Quinidine Inhibition of NaVl.5 current that governs the upstroke velocity of phase 0 of the cardiac AP significantly reduces the upstroke velocity and prolongs the AP duration, independent of hERG blockade (false negative) Roden and Hoffman (1985) Ducroq et al. (2007)... 

Dual channel blockers Verapamil Verapamil-induced prolongation of AP duration due to its hERG blocking properties is negated by its inhibitory effect on cardiac calcium channels (false positive) Zhang et al. (1999) Redfem et al. (2003)... 

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