Figure 8.

Multiplicative properties of tortuosities. Curve labeled ‘λ_g’ represents tortuosity computed, using Eq (11), from an MCell simulation in a medium with cubes and voids (i.e. one cube in eight removed) as a function of time after release of 5000 Ca²⁺ molecules from origin. Curve labeled ‘λ_m’ represent a similar tortuosity calculation in a medium containing only matrix at a concentration of 2.34 μM (i.e. no geometry present). Curve labeled ‘λ’ represents tortuosity calculated in a medium with cubes and voids but with a quantity of matrix in the voids such that the matrix concentration averaged over the whole ECS is also 2.34 μM. Finally, ‘λ_c’ represents the product of the λ_g and λ_m curves. It is seen that λ and λ_c are close in value. Parameters: k_f, k_b and D as for Fig. 7; α = 0.2.