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Red blood cells stabilize flow in brain microvascular networks

Fig 1

The relative velocity difference is smaller at divergent than at convergent capillary bifurcations.

(A-B) Examples of an in vivo divergent (A) and convergent (B) capillary bifurcation. (C) Line scans for the divergent bifurcation in (A). (D) RBC velocity in the daughter vessels of a divergent bifurcation in vivo. Dotted lines: median of each velocity. The velocity measurements have been performed consecutively (Methods). Further examples: S5 Fig. (E) Upper plot: Bulk flow velocity in the daughter vessels of a divergent bifurcation for the simulation with red blood cells (RBCs, Methods). The time course has been smoothed by a moving average (Methods). Lower plot: Instantaneous relative velocity difference . Dotted lines: median of each variable. Blue box: , well-balanced flow situation. Further examples: S6 Fig. (F-J) Histogram: Distribution of the relative velocity difference at divergent (F, H, J) and convergent (G, I) capillary bifurcations for the simulation with RBCs (H, I) with passive particles, pPs (J) and in vivo (superscript: RBC; F, G). The histograms are normalized, i.e., the density of the underlying empirical distributions is displayed. Lower plot: Raw data for histograms. Blue bars: Well-balanced bifurcations (). DoWB: Degree of well-balanced bifurcations: ratio of the number of well-balanced bifurcations to the total number of bifurcations (n). A detailed analysis of the distributions is provided in the Methods. (K) Cumulative density of |Δ^rv| for the simulation with RBCs and the in vivo measurements. Filling indicates regions where the cumulative density of divergent bifurcations is larger than that of convergent ones. For all in vivo measurements (D, F-G, K) the RBC velocity is displayed instead of the bulk flow velocity (superscript: RBC). Mouse icon: in vivo measurements. Computer icon: simulation results.

doi: https://doi.org/10.1371/journal.pcbi.1007231.g001