Effects of Temperature on Arachidonic Acid-Induced Cellular Edema and Membrane Perturbation in Rat Brain Cortical Slices

The effects of temperature on arachidonic acid-induced cellular edema in the first cortical brain slices of rats were studied. Incubation of the cortical slice in arachidonic acid at 37 degrees C induced cellular swelling, and increased intracellular Na+ and lactic acid contents concomitant with decreased intracellular K+. When the incubation temperature was reduced these changes were reduced in severity. The uptake of [3H]arachidonic acid in cortical slices was temperature-dependent. The incorporation of [3H]arachidonic acid into various lipid fractions was further studied by HPLC. The majority of [3H]arachidonic acid was incorporated into triacylglycerol and phosphatidylinositol (PI), but the incorporation of [3H]arachidonic acid into PI was temperature-dependent, unlike that into other phospholipids and neutrolipids. Further, cortical (Na+ + K+)-ATPase activity was inhibited whereas its subunit K+-activated p-nitrophenyl-phosphatase was activated by arachidonic acid at various incubation temperatures. The effects of arachidonic acid on these enzymes is similar to that of thimerosal, a lipid removal agent. These data suggest that both temperature and arachidonic acid play an important role in the development of cellular edema associated with membrane perturbation and inactivation of (Na+ + K+)-ATPase activity.