Spontaneous and experimentally evoked [Ca 2+] i-transients in cardiac myocytes measured by means of a fast Fura-2 technique

A setup for dual wavelength-excitation fluorescence measurements is introduced which permits a temporal resolution of up to 1 KHz, using the Ca 2+-sensitive fluorescent dye Fura-2. The system makes use of a novel technical solution for chopping between two excitation wavelengths which does not move any optical components. Two beams, which are alternatively opened or shut by a rotating chopper wheel, are united by a dichroic mirror and are used for low-noise epifluorescence microscopy. The system includes a device for fast changes of extracellular solution that can be used for studying various components of [Ca 2+] i-regulation in excitable and non-excitable cells. Sample recordings of spontaneous and experimentally-evoked [Ca 2+] i-transients from cardiac myocytes are presented. Cardiac myocytes are a cell species that produces particularly fast [Ca 2+] i-transients and therefore, a high temporal resolution is required in order to study physiological and/or pharmacological properties of these transients.