EMCCD optical mapping system for measurement of action potentials
ŠVRČEK, M. RUTHERFORD, S. CHEN, A. SMAILL, B. PROVAZNÍK, I.
Optical mapping using membrane potential-sensitive fluorescent dyes provides a means of recording electrical activation on the heart surface with high spatial resolution. However, in order to interpret these data, it is necessary to correct for artifacts introduced by heart wall motion. The new optical system based on EMCCD camera is designed to be able to record optical signal in high resolution 128x128 at 400fps (via a 550nm> long-pass filter). The system allows use of new ratiometric technique. Image sequences can be recorded sequentially with and without a second long-pass filter (620nm>) which is introduced into the light path using a fast purpose-built translation system. The system consist of the novel chamber design which allows simultaneously recordings of optical signal on the one side of the heart as well as electrical on another one, all in physiological temperatures. The heart is illuminated with 2 blue LEDs (Luxen V Star, LHXL-LB5C), each equipped with a small reflector, short pass filter (505 nm) and cooling fan. The LEDs were driven at 700 mA using a power supply (POWERTECH, MP3087) in current control mode. The LEDs are equipped with electronic shutter. Perfusion is controlled with Imed PC-2 micropump, the heart temperature is controlled by thermo-regulator. This system brings new advantages of using ratiometry techniques on 2D based recordings and allows several improvements in optical mapping techniques including novel image registration approach which rely on relatively high spatial resolution.
Opttical mapping, dye, EMCCD camera, array of electrodes, Di-4ANEPPS, action potential
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