Studies on Effect of Gamma Radiation on Prostacyclin and Platelet-Activating Factor Synthesis and on Cell Growth Using Smooth Muscle, Fibroblast, and Endothelial Cells in Cultures
The effect of gamma radiation on cell division and the synthesis of prostaglandin and platelet-activating factor was studied using homogeneous cultures of smooth muscle, fibroblast, and endothelial cells isolated from the calf pulmonary artery. Exposure of these cultures to doses of up to 30 Gy resulted in some differences in the ability of the cultures to continue their growth. The endothelial cultures, which were the most rapidly proliferating at the time of irradiation, proved the most easily growth inhibited compared to the smooth muscle cells and fibroblasts. On the other hand, the production of prostacyclin, in response to the addition of bradykinin and arachidonate, increased considerably within 30 hours of irradiation in all three cell types. Maximum activation was observed at 10 Gy. Exposure of smooth muscle cells to a trapper of oxygen radicals after irradiation reduced the radiation-induced increase in prostacyclin (PGI2) synthesis by about 60% in both the bradykinin- and arachidonate-treated cultures. Since the added arachidonate was illustrated to be directly converted to PGI2 without preliminary esterification, these experiments suggest that the cyclooxygenase complex activity was being affected. However, the synthesis of platelet-activating factor in endothelial cells in response to bradykinin and ionophore A23187 also increased almost twofold in response to irradiation, further suggesting that the action of phospholipase A2 is also affected by gamma irradiation.
KeywordsSmooth Muscle Cell Gamma Radiation Pulmonary Artery Smooth Muscle Cell Homogeneous Culture Pulmonary Artery Endothelial Cell
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