Microwave induced stimulation of 32Pi incorporation into phosphoinositides of rat brain synaptosomes med./bio.

To study the effect of microwave exposure on the metabolism of synaptosomal membrane phospholipids. ³²Pi-incorporation into phosphoinositides was studied.

• rat brain synaptosomes

Irradiation of synaptosomes at a power density of 10 mW/cm² or more produced stimulation of the ³²Pi-incorporation into phosphoinositides. The extent of ³²Pi-incorporation was found to be much more pronounced in phosphatidylinositol-4-phosphate (PIP), and phosphatidylinositol-4,5-bisphosphate (PIP2) as compared to phosphatidylinositol (PI) and phosphatidic acid (PA). Inclusion of 10 mM lithium (Li⁺) in the medium decreased the basal labeling of PIP2, PIP and PI and increased PA labeling. Li⁺ also inhibited the microwave stimulated PIP2, PIP and PI labeling but had no effect on PA labeling. Calcium ionophore (A23187) inhibited the basal and microwave stimulated ³²Pi labeling of PIP and PIP2, stimulated basal labeling of PA and PI and had no effect on microwave stimulated PA and PI labeling. Calcium chelator (EGTA) on the other hand, had no effect on basal labeling of PA and PI, stimulated basal PIP and PIP2 labeling but did not change microwave stimulated labeling of these lipids. Microwave exposure did not produce any significant effect on the endogenous concentrations of the total as well as individual phospholipids of synaptosomes indicating that only phosphoinositide turnover was stimulated.