Muscle venous PO2 and VO2 are linearly related in repetitive tetanic contractions of canine muscle during hypoxic hypoxia.
1. It has previously been shown that perfusion with high O2-affinity-erythrocytes decreases venous PO2 (PVO2) and decreases O2 uptake (VO2) in contracting muscle at the same O2 delivery (arterial O2 concentration x flow). A linear VO2-PVO2 relationship has been obtained with a VO2-axis intercept, suggesting that, during this type of hypoxia, VO2 is composed of a PVO2-dependent and -independent VO2. However, the VO2-PVO2 relation during hypoxic hypoxia has not been examined. 2. To clarify this relation, PVO2 and VO2 have been measured in contracting gastrocnemius (1 Hz trains of 0.2 s isometric tetani) under both normoxic and hypoxic conditions during 5 min of stimulation. 3. Venous O2 changes proportionally with O2 delivery. Each VO2-PVO2 relation was linear, with the mean described by the equation VO2 = 5.06 + 0.41 x PVO2 (n = 6, r = 0.81, P < 0.05). The VO2-axis intercept was significantly different from zero (P < 0.05). 4. These results were similar to those obtained during hypoxia induced by high O2-affinity-erythrocytes. We conclude that there is a linear relationship between PVO2 and VO2 above the VO2-axis intercept, regardless of the type of hypoxia.
Kohzuki
H
H
Department of Physiology II, Nara Medical University, Kashihara, Japan. hkohzuki@naramed-u.ac.jp
Misawa
H
H
Kishi
T
T
Ohga
Y
Y
Sakata
S
S
Takaki
M
M
D000818:Animals; D015687:Cell Hypoxia; D004058:Diffusion; D004285:Dogs; D009119:Muscle Contraction; D018482:Muscle, Skeletal / Q000098:blood supply / Q000378:metabolism*; D010100:Oxygen / Q000378:metabolism*; D010101:Oxygen Consumption; D010313:Partial Pressure; D014680:Veins
D010100:Oxygen