Estimation of action potential changes from field potential recordings in multicellular mouse cardiac myocyte cultures.

BACKGROUND Extracellular recordings of electrical activity with substrate-integrated microelectrode arrays (MEAs) enable non-invasive long-term monitoring of contracting multicellular cardiac preparations. However, to characterize not only the spread of excitation and the conduction velocity from field potential (FP) recordings, a more rigorous analysis of FPs is necessary. Therefore in this study we aim to characterize intrinsic action potential (AP) parameters by simultaneous recording of APs and FPs. METHODS A MEA consisting of 60 substrate-integrated electrodes is used to record the FP-waveform from multicellular preparations of isolated embryonic mouse cardiomyocytes. Simultaneous current clamp recordings in the vicinity of individual microelectrodes and pharmacological interventions allowed us to correlate FP and AP components and their time course. RESULTS The experiments revealed a linear relationship between AP rise time and FP rise time as well as a linear relationship between AP duration and FP duration. Furthermore a direct contribution of the voltage dependent Na(+)- and Ca(2+)-current to the FP could be identified. CONCLUSION The characterization of the FP allows us for the first time to estimate AP changes and the contribution of individual current components to the AP by the help of non-invasive recording within a multicellular cardiac preparation during long-term culture.