MEASUREMENTS OF SARCOMERE DYNAMICS SIMULTANEOUSLY WITH AUXOTONIC FORCE IN ISOLATED CARDIAC-CELLS

We developed an easy to use and non-invasive method to study sarcomere motion of enzymatically isolated myocytes which can be simultaneously combined with auxotonic force detection, thus being very useful when studying the contractile performance of cardiac cells. This method bas ically consists in analyzing the periodicity of the cell striation pat tern using the Cooley-Tukey fast Fourier transform (FFT) algorithm on a video image of the cell during the course of the experiment. A longi tudinal fraction of the cell image is recorded with a CCD TV camera, d igitized, then transiently stored on a computer and used to calculate the spectrum corresponding to the distribution of the sarcomere length s (SL). The method gives a real-time measurement of the most probable value of sarcomere length in one isolated cell with a temporal resolut ion of 20 ms. When used on a cell attached between two carbon fibers, the auxotonic force developed by the cell upon electrical stimulation can be simultaneously measured. together with the SL in various condit ions of stretch. Preliminary results have been presented in abstract f orm (Gannier et al., vol 24, pp. S47, 1992).