This article shows the combination of light activatable ion channels and microelectrode array (MEA) technology for bidirectionally interfacing cells. HL-1 cultures, a mouse derived cardiomyocyte-like cell line, transfected with channelrhodopsin were stimulated with a microscope coupled 473 nm laser and recorded with custom built 64 electrode MEAs. Channelrhodopsin induced depolarization of the cell can evoke action potentials (APs) in single cells. Spreading of the AP over the cell layer can then be measured with good spatiotemporal resolution using MEA recordings. The possibility for light induced pacemaker switching in cultures was shown. Furthermore, the suppression of APs can also be achieved with the laser. Possible applications include cell analysis, e.g. pacemaker interference or induced pacemaker switching, and medical applications such as a combined cardiac pacemaker and defibrillator triggered by light. Since current prosthesis research focuses on bidirectionality, this system may be applied to any electrogenic cell, including neurons or muscles, to advance this field.