Interaction between oxygen and the blood vessel wall
Pittman, R.N.
Canadian Journal of Cardiology 2(2): 124-131
1986
ISSN/ISBN: 0828-282X PMID: 3085905 Document Number: 272845
Blood vessels in vivo respond to changes in the supply of oxygen relative to its demand. Whether the vessels which participate in such vasoregulatory responses are directly affected by oxygen remains an open question. Most studies of oxygen sensing by blood vessels have been carried out on strips, rings or segments isolated from relatively large vessels. These preparations are generally sensitive to oxygen from 0 mm Hg to some upper PO2 (10 to 240 mm Hg) whose value depends on experimental conditions. It appears unlikely that reduced energy production secondary to tissue hypoxia is directly responsible for the relaxation usually observed when PO2 is lowered below a critical value. Evidence that an oxygen-linked chemical mediator such as adenosine or prostacyclin is involved in contractile responses to lowered PO2 has been obtained. The site of action of oxygen could be anywhere within the vascular wall, but current evidence suggests a prominent role for the endothelial cells. At present extrapolation of these results to resistance vessels in vivo must be carried out with caution due to potential differences in the behaviour of microvessels relative to large vessels.