Calcium waves in mammalian heart: quantification of origin, magnitude, waveform, and velocity.
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
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Department of Physiology, University of Maryland School of Medicine, Baltimore 21201.
Wier
W G
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D000818:Animals; D002118:Calcium / Q000378:metabolism* / Q000502:physiology; D005456:Fluorescent Dyes; D006168:Guinea Pigs; D007091:Image Processing, Computer-Assisted; D066298:In Vitro Techniques; D007211:Indoles; D008564:Membrane Potentials / Q000502:physiology; D008856:Microscopy, Fluorescence; D009206:Myocardium / Q000378:metabolism*; D009991:Oscillometry; D014741:Video Recording
D005456:Fluorescent Dyes; D007211:Indoles; C048960:indo-1; D002118:Calcium