Activation of PLA2 isoforms by cell swelling and ischaemia/hypoxia

Phospholipase A(2) (PLA(2)) activity is increased in mammalian cells in response to numerous stimuli such as osmotic challenge, oxidative stress and exposure to allergens. The increased PLA(2) activity is seen as an increased release of free, polyunsaturated fatty acids, e.g. arachidonic acid and membrane-bound lysophospholipids. Even though arachidonic acid acts as a second messenger in its own most mammalian cells seem to rely on oxidation of the fatty acid into highly potent second messengers via, e.g. cytochrome P450, the cyclo-oxygenase, or the lipoxygenase systems for downstream signalling. Here, we review data that illustrates that stress-induced PLA(2) activity involves various PLA(2) subtypes and that the PLA(2) in question is determined by the cell type and the physiological stress condition.