A radioenzymatic assay to identify three groups of phospholipase A2 in platelets

Phospholipases A2 (PLA2) are key enzymes in membrane metabolism. The release of fatty acids and lysophospholipids by PLA2 activates several intra-cellular second messenger cascades that regulate a wide variety of physiological responses. The aim of the present study is to describe a radioenzymatic assay to determine the activity of three main PLA2 subtypes in platelets, namely extracellular calcium-dependent PLA2 (sPLA2) and intracellular calcium-dependent (cPLA2) and calcium-independent PLA2 (iPLA2). The differentiation of these distinct PLA2 subtypes was based on the enzyme substrate preference (arachdonic acid or palmitoyl acid) and calcium concentration. Our results indicate that this new assay is feasible, precise and specific to measure the activity of the aforementioned subtypes of PLA2. Therefore, this protocol can be used to investigate modifications of PLA2 homeostasis in distinct biological models addressing the pathophysiology of many medical and neuropsychiatric disorders such as schizophrenia and Alzheimer's disease.