Fig 8. Individual cortical PO₂ (P_tO₂) measured in the MCA territory in the non-ischemic hemisphere (left) and ischemic hemisphere (right) under the control and hyperoxia conditions in SHR (top) and Wistar rats (bottom; n = 5 and 4, respectively).

Each line joins P_tO₂ values obtained under both conditions for a single rat; different colors are used for ease of illustration. The inset on the top right zooms on the four SHRs with lowest baseline P_tO₂ values, which are difficult to discriminate on the main graph due to the common scale used across graphs. This figure shows lower P_tO₂ under ischemic vs control condition in both strains, and increases in P_tO₂ under hyperoxia in all 9 rats (although of very small amplitude in one SHR), which was highly statistically significant with pooled data. However, due to small samples and highly variable P_tO₂ increases, only trends were found when strains were assessed separately. The increase in P_tO₂ by hyperoxia was not significantly different between the two strains in the ischemic cortex, although was significantly higher for Wistar rats in the contralateral hemisphere. Statistical tests also showed significantly higher P_tO₂ in the control condition in Wistar rats as compared to SHRs in both hemispheres (see Results for further details).