In Vivo Studies of Mitochondrial Respiration
In the course of an investigation of adding new collateral blood flow to the cortex of ischemic patients, the point was raised as to whether an increase in cortical oxygen tension would lead to improved oxygen utilization and energy production. If so, this might at least partially supply an explanation for improved neurologic function. The work on isolated mitochondria is firm in stating that there is no decrease in O2 utilization until less than 0.1 mmHg ambient PO2 (Chance et al, 1955, 1973). On the other hand, recent work on in vivo mitochondria suggest that they may respond differently, i.e., changes in cortical mitochondrial respiration may occur at a much higher brain PO2 (Rosenthal et al, 1975 & Austin et al, 1975). To investigate this problem, the authors used cats anesthetized similarly to humans undergoing microanastomosis surgery. Previous reported studies by others had shown the cytochrome a3 end of the respiratory chain to be more responsive to changes in O2 concentration. In the present study, the authors have added measurements of relative cortical PO2 (bPO2), relative cortical O2 utilization (bṖO2), and a power spectral analysis of the cortical electrical activity to obtain a measure of functional brain metabolism.
KeywordsMitochondrial Respiration Power Spectral Analysis Collateral Blood Flow Ischemic Patient Femoral Artery Catheter
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