We investigated the influence of hyperoxia on O2 uptake in tetanically contracting canine gastrocnemius. Hyperoxia showed neither increase in O2 uptake nor decrease in lactate release, irrespective of increased O2 supply, venous Po2 and vascular resistance, as compared to normoxia, suggesting that hyperoxia decreases O2 diffusion conductance and/or effective O2 supply probably due to arteriovenous O2 diffusion shunt.
