Saltatory propagation of Ca2+ waves by Ca2+ sparks.
Punctate releases of Ca2+, called Ca2+ sparks, originate at the regular array of t-tubules in cardiac myocytes and skeletal muscle. During Ca2+ overload sparks serve as sites for the initiation and propagation of Ca2+ waves in myocytes. Computer simulations of spark-mediated waves are performed with model release sites that reproduce the adaptive Ca2+ release observed for the ryanodine receptor. The speed of these waves is proportional to the diffusion constant of Ca2+, D, rather than D, as is true for reaction-diffusion equations in a continuous excitable medium. A simplified "fire-diffuse-fire" model that mimics the properties of Ca2+-induced Ca2+ release (CICR) from isolated sites is used to explain this saltatory mode of wave propagation. Saltatory and continuous wave propagation can be differentiated by the temperature and Ca2+ buffer dependence of wave speed.
Institute of Theoretical Dynamics and Section on Neurobiology, Physiology, and Behavior, University of California, Davis, California 95616 USA. jkeizer@ucdavis.edu
J
J
Keizer
G D
GD
Smith
S
S
Ponce-Dawson
J E
JE
Pearson
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism*; D003198:Computer Simulation; D004058:Diffusion; D007700:Kinetics; D008954:Models, Biological; D018482:Muscle, Skeletal / Q000378:metabolism*; D009206:Myocardium / Q000378:metabolism*; D019837:Ryanodine Receptor Calcium Release Channel / Q000378:metabolism*
D019837:Ryanodine Receptor Calcium Release Channel; D002118:Calcium