Abstract
Aim: We established a preparation of adult murineventricular slices suitable for electrophysiologicalrecordings as a new in vitro model of adultmyocardium with preserved in vivo tissue structure.Methods: Short axis slices (thickness: 150 µm) ofadult murine ventricles were prepared with amicrotome. Sharp glass electrodes were used formeasurements of action potentials (APs) atstimulation frequencies of 2 Hz and 10 Hz. Fieldpotential (FP) recordings by means of microelectrodearrays (MEAs) were performed to map excitationspread. Results: APs showed the characteristics ofadult murine ventricular APs: (i) a stable restingmembrane potential, (ii) a fast upstroke and (iii) afast phase 1 repolarization. Application of the Na+channel blocker lidocaine (30 µM) led to a declineof upstroke slope, amplitude and conduction speed.The unspecific K+ channel blocker 4-aminopyridine(5 mM) caused a prolongation of APD50. The excitationspread was homogenous throughout the ventricularwall. Conclusion: Adult murine ventricular slices areelectrophysiologically intact and respondphysiologically to cardioactive drugs. Thus, theyprovide a new multicellular in vitro model of adultcardiac tissue suitable for electrophysiologicalinvestigations, which in future could be used to studythe functional integration of stem cells transplantedin infarcted hearts in vivo.
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