Theoretical simulation of oxygen transport to brain by networks of microvessels: effects of oxygen supply and demand on tissue hypoxia.
OBJECTIVE
Simulations of oxygen delivery by a three-dimensional network of microvessels in rat cerebral cortex were used to examine how the distribution of partial pressure of oxygen (PO2) in tissue depends on blood flow and oxygen consumption rates.


METHODS
Network geometry was deduced from previously published scanning electron micrographs of corrosion casts. A nonlinear least-squares method, using images obtained at three different angles, was used to estimate vessel locations. The network consisted of 50 segments in a region 140 microm x 150 microm x 160 microm. A Green's function method was used to predict the PO2 distribution. Effects of varying perfusion and consumption were examined, relative to a control state with consumption 10 cm3O2/100 g per min and perfusion 160 cm3/100 g per min.


RESULTS
In the control state, minimum tissue PO2, was 7 mm Hg. A Krogh-type model with the same density of vessels, but with uniform spacing, predicted a minimum tissue PO2 of 23 mm Hg. For perfusion below 60% of control, tissue hypoxia (PO2 <1 mm Hg) was predicted. When perfusion was reduced by 75%, the resulting hypoxia could be eliminated by a 31% reduction in oxygen consumption rate.


CONCLUSIONS
The simulations suggest that tissue hypoxia resulting from a severe decrease in brain perfusion, as can occur in stroke, may be avoided by a moderate decrease in oxygen consumption rate.
Secomb
T W
TW
Department of Physiology, University of Arizona, Tucson 85724-5051, USA. secomb@u.arizona.edu
Hsu
R
R
Beamer
N B
NB
Coull
B M
BM
D000818:Animals; D001692:Biological Transport; D001783:Blood Flow Velocity; D001921:Brain / Q000098:blood supply / Q000378:metabolism; D015687:Cell Hypoxia / Q000187:drug effects; D002560:Cerebrovascular Circulation / Q000502:physiology*; D003198:Computer Simulation; D016319:Corrosion Casting; D002534:Hypoxia, Brain / Q000097:blood; D008833:Microcirculation; D008855:Microscopy, Electron, Scanning; D008954:Models, Biological; D010100:Oxygen / Q000097:blood* / Q000494:pharmacology; D010101:Oxygen Consumption; D010477:Perfusion; D051381:Rats
D010100:Oxygen