title: Effect of cardioactive drugs on action potential generation and propagation in embryonic stem cell-derived cardiomyocytes.
abstract: Extracellular recordings of spontaneous electrical activity in contracting cardiac clusters differentiated from murine embryonic stem cells enable to study electrophysiological features of this in-vitro cardiac-like tissue as well as effects of pharmacological compounds on its chronotropy and electrical conduction. To test if the microelectrode array (MEA) system could serve as a basis for development of a pharmacological screening tool for cardioactive drugs, we used spontaneously beating outgrowths of three-dimensional ES cell aggregates ("embryoid bodies", EBs) plated onto substrate-integrated MEAs. The effects of the L-type Ca(2+) channel antagonist verapamil and Na(+) and K(+) channel blockers (tetrodotoxin, 4-aminopyridine, and sparfloxacin) on the deduced interrelated cardiac network function were investigated. Application of 10(-6) M verapamil led to arrhythmic spiking with a burst-like pattern; at a higher concentration (10(-5) M) the drug caused a sustained negative chronotropy up to complete stop of beating. In the presence of tetrodotoxin a conduction block was observed. Since modulation of K(+) channel activity can cause anti- or proarrhythmic effects, the influence of K(+) channel blockers, namely 4-aminopyridine and sparfloxacin, was investigated. 4-aminopyridine (2x10(-3) M) significantly stabilized beating frequency, while the field potential duration (FPD) was concentration-dependently prolonged up to 2.7-fold. Sparfloxacin (3x10(-6) M) stabilized the beating frequency as well. At a higher concentration of sparfloxacin (3x10(-5) M), a significant prolongation of the spike duration was registered; application of the drug caused also early afterdepolarizations. The results demonstrate a suitability of the studied in-vitro cardiac cell model for pharmacological drug testing in cardiovascular research.
authors.affiliation: Institute for Neurophysiology, University of Cologne, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Reppel
authors.forename: Peter
authors.initials: P
authors.lastname: Igelmund
authors.forename: Ulrich
authors.initials: U
authors.lastname: Egert
authors.forename: Frieder
authors.initials: F
authors.lastname: Juchelka
authors.forename: Jürgen
authors.initials: J
authors.lastname: Hescheler
authors.forename: Irina
authors.initials: I
authors.lastname: Drobinskaya
mesh_terms: D000200:Action Potentials / Q000187:drug effects*; D000818:Animals; D002317:Cardiovascular Agents / Q000494:pharmacology*; D053595:Embryonic Stem Cells / Q000166:cytology* / Q000187:drug effects; D024841:Fluoroquinolones / Q000494:pharmacology; D006321:Heart / Q000187:drug effects*; D007473:Ion Channels / Q000187:drug effects; D051379:Mice; D008839:Microelectrodes; D032383:Myocytes, Cardiac / Q000166:cytology* / Q000187:drug effects*; D013779:Tetrodotoxin / Q000494:pharmacology; D014700:Verapamil / Q000494:pharmacology
chemical_list: D002317:Cardiovascular Agents; D024841:Fluoroquinolones; D007473:Ion Channels; D013779:Tetrodotoxin; D014700:Verapamil; C061363:sparfloxacin