Brain Phospholipid Metabolism During Ischemia

Molecular mechanisms accounting for the vulnerability of brain to ischemic damage are incompletely understood. To assess the role of membrane integrity, phospholipid metabolism is investigated in subcellular organelles of brain following varying degrees of ischemia. Global brain ischemia is produced in rabbits by combining hypotension and hypoxia (4% oxygen). Restoration of blood pressure and oxygen after a three-minute isoelectric EEG results in full recovery, while a five-minute isoelectric EEG results in either a lack of recovery or neurological deficits. Quantitative analysis of seven phospholipids in subcellular organelles shows no consistent pattern of phospholipid changes following ischemia. Incorporation of radioactive phosphate, on the other hand, discloses moderate alterations following five-minute ischemia. These findings indicate that brain ischemia provokes phospholipid changes, but their role in impairing membrane integrity and in initiating irreversible ischemic brain damage is uncertain.