Underlying mechanisms of circular calcium wave propagation in rat ventricular myocytes

It was hypothesized that subcellular organelles counteracted the higher release site density along Z-lines by acting as transverse diffusion barriers. The ratio of the longitudinal diffusion coefficient to the transverse coefficient was 2.6, supporting the hypothesis of transverse diffusion barriers. The combination of release sites clustered at the Zlines and a transverse diffusion coefficient 50% fo that in the longitudinal dirrection generated elliptical waves of eccentricity 4/3. Introducing putative release sites between the Z-lines at a density 20% of that on the Z-lines produced circular waves. The experiments and simulations support the presence of transverse diffusion barriers, and possibly intermediate release sites also.