Effect of Nine Reference Compounds
Autonomic Nervous System: Adrenergic stimulation using isoproterenol increased the beating rate between +64% to +85%. As expected, cholinergic stimulation using carbachol slowed beating between -18% and -11% at first and second addition (which differed in concentration, whereby the first addition was the lower and the second addition the higher concentration). Interestingly, mESC-CM reacted stronger to carbachol than hiPS-CM, with contractions blocked at first compound addition.
L-type calcium current: Using amlodipine to block the L-type calcium current stopped beating in human cells at second compound addition and in mouse cells already at first addition, suggesting concentrations were too high and immediately toxic.
T-type calcium current: Effect of blocking T-type calcium channels was tested using four different compounds. Mibefradil did not show any effect on the concentrations used in hiPS-CM, whereas contractions in mESC-CM were inhibited at the second addition. The higher sensitivity of mESC-CM toward T-type calcium channel blockers was confirmed using three additional compounds.
hERG current: This current plays an important role during repolarization of the action potential. hERG current block is a frequent side effect, which can prolong the QT interval resulting in lethal ventricular arrhythmia torsade de pointes. The E-4031 specific hERG channel blocker decreased beating rate and induced irregular beating at first compound addition.
Pacemaker current: This current plays a key role in the spontaneous beating of nodal cells. As expected, Zatebradine reduced beating rate in both CM models.
This research study showed that the xCELLigence Cardio Instrument has potential for 96-well throughput screening of compounds for effects on cardiac beating patterns.