Regional cerebral metabolic rate for glucose immediately following exposure to two atmospheres absolute oxygen in conscious rats.
Hyperbaric oxygenation (HBO) at different pressures produces significant increases in the regional cerebral metabolic rate for glucose (rCMRgl) of various neuroanatomical structures in conscious rats. These increases in rCMRgl precede the neurological signs of oxygen toxicity. In previous studies 1- and 4-h exposures to 2 atmospheres absolute oxygen (ATA O2) produced significant increases in rCMRgl of several neuroanatomical structures. These observations are now extended to include the rCMRgl changes produced during a brief 30-min exposure to 2 ATA O2. The purpose of the present study was to investigate whether HBO has an immediate effect on rCMRgl and to determine the neuroanatomical basis of changes in brain energy metabolism during an early stage of HBO. The rCMRgl was autoradiographically measured by 2-[14C]deoxyglucose technique in conscious unrestrained rats exposed either to air at atmospheric pressure or oxygen at 2 ATA O2 for 30 min. Statistically, no significant changes in rCMRgl were observed between air-exposed and oxygen-exposed groups in the 28 neuroanatomical structures examined. It is concluded that HBO requires a certain amount of time to elicit its effect on rCMRgl in a given pressure. However, the neuroanatomical origins of the previously observed increases in rCMRgl during prolonged HBO could not be detected in this early period of exposure to 2 ATA O2.
PubMed Abstracts
PubMed Abstracts