Figure 5. Values of LD-CBF, cortical tPO₂ and CMRO₂.

A, mean values of relation of LD-CBF normalized to the per cent high voltage low frequency ECoG state (HVLF and LVHF), during 60 min control period, first and second 20 min periods of hypoxia, and 60 min recovery period. The continuous and dotted lines represent significant differences (P < 0.01) in LD-CBF for HVLF and LVHF states, respectively, between the control and hypoxic periods. As seen, LD-CBF increased significantly in response to hypoxia during both HVLF and LFHF states. B, cortical tissue values (Torr) as function of ECoG state during control, hypoxia and recovery periods. C, cerebral metabolic rate for O₂ as per cent of HVLF control, during periods of normoxia, 20 and 40 min isocapnic hypoxia, and recovery. As is evident, CMRO₂ decreased significantly for the LVHF state during both periods of hypoxia (P < 0.05). Values are mean ±s.e.m., n for each value 20–200; HVLF, high voltage low frequency; LVHF, low voltage high frequency.