AJP - Heart and Circulatory Physiology, Vol 234, Issue 5 582-H591, Copyright © 1978 by American Physiological Society
Role of tissue hypoxia in local regulation of cerebral microcirculation
H. A. Kontos, E. P. Wei, A. J. Raper, W. I. Rosenblum, R. M. Navari and J. L. Patterson Jr
The mechanism of action of hypoxia on cerebral blood vessels and its role
in the regulation of the cerebral circulation were investigated in
anesthetized cats. Arterial hypoxia produced marked cerebral arteriolar
vasodilation, which was partially reversed by perfusing the space under the
cranial window with artificial cerebrospinal fluid (CSF) containing 6-94%
oxygen. More marked increase in the local supply of oxygen, via perfusion
of the space under the cranial window with fluorocarbon FC-80 equilibrated
with 100% oxygen, completely eliminated the vasodilation induced by
arterial hypoxia. Fluorocarbon equilibrated with 100% N2 had no effect on
the vasodilation. The vasodilation associated with hypotension was
completely reversed by perfusion with fluorocarbon equilibrated with 100%
oxygen and was unaffected by perfusion with fluorocarbon or CSF
equilibrated with gas not containing oxygen. The vasodilation associated
with Metrazole-induced seizures was partially reversed by perfusion with
fluorocarbon containing oxygen. The results show that hypoxia dilated
cerebral blood vessels entirely via a local mechanism, that hypoxia is the
dominant mechanism involved in the vasodilation associated with
hypotension, and that it is, at least partially, responsible for the
vasodilation associated with seizures.
