[Release of arachidonate from rat spleen lymphocytes after irradiation].

After spleen lymphocytes incubation with 14C-arachidonic acid 14C label was found associated predominantly with phosphatidylethanolamine (PE) and phosphatidylcholine (PC). Addition of 0.5 mkM a 23187 to the incubation media with 2 mM CaCl2 caused a 4-fold increase in release of labeled free arachidonate in lymphocytes of the control animals. A dose-dependent increase in release of free arachidonate and membrane Ca(2+)-dependent phospholipase activity towards exogenous 2-14C-arachidonoyl-PE and -PC take place in a period 6-12 h after animal's irradiation in a doses 0.5 and 1.0 Gy. The maximum arachidonate release in 6h following 1 Gy irradiation correlates with activation of more active phospholipase A2, hydrolyzing PE. Free arachidonate is supposed to be mobilized from different phospholipid pools, depending on the content of Ca2+ in the cells after irradiation.