In preparation for tracheal intubation during induction of anesthesia, the patient may be ventilated with 100% oxygen. To investigate the impact of acute isocapnic hyperoxia on endothelial activation and vascular remodeling, ten healthy young men (24±3 years) were exposed to 5-min normoxia (21% O₂) and 10-min hyperoxia trials (100% O₂). During hyperoxia, intercellular adhesion molecules (ICAM-1) (hyperoxia: 4.16±0.85 vs normoxia: 3.51±0.84 ng/mL, P=0.04) and tissue inhibitor matrix metalloproteinase 1 (TIMP-1) (hyperoxia: 8.40±3.84 vs normoxia: 5.73±2.15 pg/mL, P=0.04) increased, whereas matrix
metalloproteinase (MMP-9) activity (hyperoxia: 0.53±0.11 vs normoxia: 0.68±0.18 A.U., P=0.03) decreased compared to the normoxia trial. We concluded that even short exposure to 100% oxygen may affect endothelial activation and vascular remodeling.