Journal of Applied Physiology, Vol 50, Issue 2 450-455, Copyright © 1981 by American Physiological Society
Blood flow and oxygen consumption in avian skeletal muscle during hypoxia
B. R. Grubb
Birds are known to be much more tolerant than mammals to high altitude [low
oxygen pressure (PO2)], and it is therefore of interest to know the
responses of their muscles to low oxygen. We studied the influence of
hypoxia on the rate of blood flow, oxygen extraction, and oxygen
consumption (VO2) in resting hindlimb muscle of ducks. We found that during
normoxia the VO2 in this muscle mass was similar to resting mammalian red
muscle. However, blood flow rate (45 ml x 100 g-1 x min-1) and venous PO2
(70 Torr) were much higher than in resting red or white mammalian muscle.
Hypoxia down to 35-40 Torr resulted in no change in blood flow, but oxygen
extraction increased dramatically as arterial PO2 fell below 70 Torr. The
resting VO2 was maintained even at the lowest arterial oxygen content (5
ml/100 ml). From these experiments it appears as though duck skeletal
muscle has a "luxuriant" resting blood flow rate that is sufficient to
supply skeletal muscle with adequate oxygen.
