Fig. 2

Propagation of stable and abortive calcium waves. (A) Axial calcium profiles of a stable calcium wave at different points in time (dendrite radius 0.4 μm, ER radius 0.15 μm, RyR density 2.5 \(\upmu \mathrm{m}^{-2}\)). The depicted cytosolic calcium profiles are recorded directly at the ER membrane and over the whole length of the model dendrite. The shape of the wave remains constant and travels from left to right in a convective manner, although driven by a reaction-diffusion process with nonlinear calcium exchange across the ER. (B) Axial calcium wave profiles of an abortive calcium wave (same setup as in A, but with a smaller ER radius of 0.11 μm). While a wavefront traveling from left to right is clearly visible, it has a smaller amplitude than in A and breaks down before reaching the far end of the dendrite. (C) Velocity of the calcium wave fronts in A and B as a function of time. The stable wave quickly reaches a constant velocity of about 1.06 \(\upmu \mathrm{m}\ \mathrm{ms}^{-1}\) and travels through the whole dendrite at this speed, while the velocity of the abortive wave peaks at about 0.98 \(\upmu \mathrm{m}\ \mathrm{ms}^{-1}\) and then declines to zero while the wave breaks down. (D) Sample simulation of a 1 μm dendrite with elicitation of a stable calcium wave. The radial coordinate is scaled by a factor of 8 to enhance visibility