The effects of mild hyperoxia and/or hypertension on oxygen availability and oxidative metabolism in acute focal ischaemia.
The effects of oxygen inhalation (FiO2 = 0.4-0.5) and/or induced hypertension (delta MBP = around 20%) on the cortical oxygen tension (CoPO2) and the cortical oxidative metabolism (NADH/NAD redox state) in acute focal ischaemia were studied in 44 rabbits. CoPO2 was recorded by a polarographical method and NADH/NAD redox state was measured with a compensated fluorometer/reflectometer. The acute focal ischaemia was induced by the occlusion of the middle cerebral artery. With oxygen inhalation, CoPO2 improved 24.8 +/- 23.2% (mean +/- SD) in ischaemic areas where CoPO2 decreased to less than 40% of control. The oxygen inhalation also partially improved NADH levels in ischaemia by 1.5 +/- 1.6% in 8 rabbits, where NADH elevated 17.6 +/- 12.1% from the normal stage. CoPO2 and NADH redox level in ischaemia were also improved by induced hypertension. delta CoPO2/delta MBP were 1.29 +/- 1.53%/mmHg in the severely ischaemic area (less than 20% of control), 1.52 +/- 0.93 in the moderately ischaemic area (20-40% of control), and 1.03 +/- 0.62 in the mildly ischaemic area (greater than 40% of control), respectively. delta NADH/delta MBP were statistically greater in the ischaemic area than in the normal cortex (p less than 0.005). It is concluded that mild hyperoxia and induced hypertension both of which are easily employed not only can improve cortical oxygen tension but also partially restore the oxidative metabolism in acute focal ischaemia.
Kaminogo
M
M
Stroke Research Foundation, University of California, Santa Barbara.
D000818:Animals; D006973:Hypertension / Q000378:metabolism*; D002546:Ischemic Attack, Transient / Q000378:metabolism*; D009243:NAD / Q000378:metabolism; D010084:Oxidation-Reduction; D010100:Oxygen / Q000378:metabolism*; D011817:Rabbits
D009243:NAD; D010100:Oxygen