Fast optical potential mapping in single cardiomyocytes during field stimulation

We have studied the process of cell excitation which was evoked and influenced by electrical fields. Optical potential mapping with very high spatial and temporal resolution (15 μm and about 30 μm, respectively) was performed in isolated ventricular cells from guinea pig using the fluorescent potential sensitive dye Di-4-Anepps and Laser excitation. Depending on duration and amplitude of the electrical pulses, rising phases were distorted extensively. Action potentials were elicited, sometimes more than a millisecond delayed. A simple model of three coupled Bee-ler-Reuter models was capable to simulate closely the develope-ment of action potentials.