Fig. 6

Range in TMA concentration curves for experimental data compared with diffusion and convection simulations with perivascular exchange. Simulations performed at a mid (50 μm min⁻¹) and high (250 μm min⁻¹) velocity based on bulk flow estimates. a Experimental data in rats from Cserr et al. (grey, n = 33) [30] compared with diffusion and mid-velocity convection simulations (blue, n = 112). Experimental median values were α = 0.18, and λ = 1.6, assuming diffusion only. For simulation, \(v\) = 50 μm min⁻¹, α = 0.18, and λ = 1.85. b Experimental data from Cserr et al. (grey, n = 33) [30] compared with diffusion and high-velocity convection simulations (blue, n = 112). For simulation, \(v\) = 250 μm min⁻¹. c Experimental data in mice from Kress et al. (grey) for female (n = 9) [25] compared with mid-velocity simulations (blue). Experimental median values were α = 0.224, and λ = 1.6, assuming diffusion only. For simulations, average bulk flow velocity = 50 μm min⁻¹, α = 0.224, and λ = 1.85. d Experimental data in mice from Kress et al. (grey) for male (n = 11) [25] compared with mid-velocity simulations (blue). Experimental and simulation parameters same as c. The range for 50 μm min⁻¹ simulation results is equivalent to the full variability reported by both Cserr et al. and Kress et al. consistent with the presence of bulk flow. Range for the 250 μm min⁻¹ simulation is much higher than experimental observations, suggesting that bulk flow in the interstitium is significantly less than 250 μm min⁻¹