High-speed ratiometric imaging revealed that [Ca2+]i waves propagate at a constant velocity of typically 100 microns/s at 22 degrees C, with a spatially steep wave front rising from 500 to 1200 nM.
A dual, digital, indo-1 fluorescence imaging system was used to obtain high-speed ratiometric images of Ca2+i waves in single voltage-clamped mammalian cardiac cells. The spatiotemporal origin of Ca2+i waves in depolarized cells was detected as the spontaneous appearance, over 100-300 ms, of domelike regions of elevated Ca2+i, approximately 20 microns in diameter and 300 nM at the center. Images of Ca2+i taken at 67-ms intervals during propagation of Ca2+i waves revealed that the Ca2+i wave front was 1) constant in shape, 2) spatially steep, typically rising from 500 to 1200 nM in about 10 microns, and 3) propagating at constant velocity, typically 100 microns/s at 22 degrees C. The observed spatial and temporal patterns of origin and propagation of Ca2+i waves are consistent with the hypothesis that Ca2+i waves arise from propagating Ca2(+)-induced release of Ca2+ mediated by diffusion of cytosolic Ca2+. The Ca2+i waves are smaller in peak magnitude and can occupy a larger fraction of the cell than thought previously on the basis of indirect observations.
Takamatsu et al. (Thu,) conducted a other in Mammalian cardiac cells. Dual, digital, indo-1 fluorescence imaging was evaluated on Spatiotemporal origin and propagation of [Ca2+]i waves. High-speed ratiometric imaging revealed that [Ca2+]i waves propagate at a constant velocity of typically 100 microns/s at 22 degrees C, with a spatially steep wave front rising from 500 to 1200 nM.