Fig. 6.

Results of oxygen transport simulation of a tissue supplied by 4 discrete capillary networks for 4 different flow distributions among the networks. The solid line in each graph shows the combined tissue Po₂ distributions for all 4 networks, while the shaded areas show the contribution from the subset of networks that are under- or oversupplied. A: tissue Po₂ distribution is presented for 1 network undersupplied at 25% of normal blood flow (0.25Q, shaded area) and the remaining 3 networks each with normal blood supply (Q) for a total blood flow to the simulated tissue of 3.25Q. B–D: results of 3 different ways to adjust the blood supply in an attempt to restore tissue Po₂ levels. B and C: represent flows that occur in response to a vasodilator that uniformly increases flow in all arterioles while D represents a regulatory system that directs flow where it is needed. B: total flow to the 4 networks was increased to normal (4Q) with a uniform 23% (100% × 4/3.25) increase in flow to each network. Flow to the undersupplied network (shaded area) increased to 0.31Q. C: flow to the undersupplied network was restored to normal by uniformly increasing flow to all networks by 4-fold such that total flow increased to 13Q, with 3 networks receiving an oversupply (4Q, shaded area). D: represents the case where blood supply to the undersupplied network was increased to normal while blood supply to the other 3 networks was maintained at normal (total flow = 4Q) and hence represents the normal tissue Po₂ distribution. Using a vasodilator cannot restore tissue oxygenation to normal since a uniform increase in flow results in some regions either undersupplied (B, shaded area) or oversupplied (C, shaded area).