AJP - Regulatory, Integrative and Comparative Physiology, Vol 256, Issue 1 78-R85, Copyright © 1989 by American Physiological Society
Cerebral oxygenation and blood flow in infant and young adult rats
N. R. Kreisman, J. E. Olson, D. S. Horne and D. Holtzman
Department of Physiology, Pharmacology, and Psychiatry, Tulane University School of Medicine, New Orleans, Louisiana 70112.
In vitro cerebral oxidative metabolism undergoes dramatic increases in
infant rats between 10 and 20 days of age. To determine this was also the
case in vivo, comparisons were made of cerebral blood flow (CBF) and
oxygenation in rats at 10, 20, and 60-90 days of age, under pentobarbital
sodium anesthesia. Measurements were made of CBF, arterial and venous O2
content, cerebral PO2 distributions, and the oxidation state of
cytochrome-c oxidase (cytochrome aa3). CBF, O2 delivery, and O2 consumption
all increased progressively with maturation. In contrast, cerebral PO2,
cytochrome aa3 oxidation state, and O2 extraction fraction were higher in
20-day-old rats than in either 10-day-old or adult rats. We attribute this
difference primarily to the high density of cerebral capillaries in the
20-day-old rat. We conclude that cerebral tissue PO2 and the oxidation
state of cytochrome aa3 are determined by the density of perfused
capillaries in addition to the more commonly accepted factors of cerebral
O2 delivery and consumption.
