Table 1.

O₂ transport parameters used to model oxygenation in the FaDu tumor and the cremaster muscle microregions.

Parameter	Unit	Value for		Description
		FaDu	Cremaster
V	mm3	0.12	0.091	Volume of the mapped region
Q	nl/min	40.0	75.0	Total blood inflow to region = sum of blood flow in all feeding arterioles
Q/V	nl/min/mm3	333	824
pO2	mm Hg	40.0	50.0	O2 partial pressure in inflowing vessels
P50	mm Hg	38.0	38.0	O2 partial pressure for half saturation of hemoglobin
N		3.0	3.0	Hill coefficient for O2 binding to hemoglobin
C0	cm3 O2/mm Hg	0.5	0.5	O2 binding capacity of red blood cells
HD		0.4	0.4	Discharge hematocrit
α	cm3 O2/cm3/mm Hg	3.1 × 10−5	3.1 × 10−5	O2 solubility
$\mathrm{\alpha }{D}_{{\mathrm{O}}_2}$	cm3 O2/cm/s/mm Hg	4.2 × 10−10	9.4 × 10−10	Krogh diffusion coefficient for O2 diffusion
$D_{{\mathrm{O}}_2}$	cm2/s	1.4 × 10−5	3.0 × 10−5	O2 diffusion coefficient
M0	cm3 O2/cm3/s	5 × 10−4	9.5 × 10−4	Rate of O2 consumption when supply is not limiting
KmO2	mm Hg	1.0	1.0	Michaelis constant for O2 consumption

Parameters were as reported previously for the FaDu (35) and the cremaster muscle microregion (56) except that M₀ in the cremaster region was adjusted to achieve the required hypoxic fraction. The chosen M₀ value is intermediate between the values previously used to represent mild and moderate levels of muscle activity (56). These O₂ transport parameters gave hypoxic fractions and median pO₂ values (Figure 3) in the range measured for tumors and normal tissues in humans using O₂ electrode histography (45).