Renormalization of regional brain blood flow during prolonged mild hypoxic exposure in rats.

In this study, we measured regional brain blood flow (BF) in rats during hypoxic exposure. Our data show the hypoxia-induced brain blood flow increase returned to baseline within 1 week as blood hemoglobin increased. Because this return to baseline occurred before capillary angiogenesis, this result suggests that the mechanism for brain blood flow renormalization during prolonged hypoxia exposure is more likely related to the increased systemic arterial oxygen carrying capacity than to local tissue hypoxia that persists for at least 2 weeks.