PaCO 2 (mm Hg) PaO 2 (mm Hg) MABP (mm Hg) Air/saline (n = 6) Baseline 36.7 ± 3.3 76 ± 10 95 ± 9 90 mins 36.0 ± 3.5 67 ± 10 95 ± 12 180 mins 34.4 ± 5.4 69 ± 8 9 7 ± 10 270 mins 34.6 ± 5.5 75 ± 7 9 9 ± 7 NBO/saline (n = 6) Baseline 37.1 ± 1.9 70 ± 7 9 8 ± 13 90 mins 47. Air, room air; NBO, normobaric hyperoxia; MABP, mean arterial blood pressure; tPA, tissue plasminogen activator. There was no difference in physiological parameters between corresponding groups of the three experiments, and thus, data were pooled for presentation purposes. *P <0.05 versus air/saline. w P <0.05 versus air groups and baseline.