GSTM1 and brain neoplasm: Of the 26 rats, 17 were excluded from the MRI study for the following reasons: MABP <100 mmHg, Hb <10 g dl−1 or pHa <7.30 during control episode (n=5); MABP <70 mmHg, PaCO2 <27 mmHg or pHa <7.30 during hypoxia episodes (n=9), absence of brain tumour (n=3).