The influence of gamma radiation on arachidonic acid release and prostacyclin synthesis.

Cultured pulmonary artery endothelial cells produce PGI2 as their primary prostaglandin. Conditions which inhibit cell division have been shown to accelerate the synthesis of this compound. Exposure of endothelial cells to gamma radiation results in an irreversible cessation of growth and enhanced production of PGI2. The level of PGI2 measured after radiation exposure exceeds that observed in cultures rendered quiescent by serum reduction. This indicates a role for gamma radiation in the elevation of PGI2 levels which is distinct from its effect on cell division. Results presented indicate that exposure to gamma radiation does not, in and of itself, elevate PG levels but capacitates cells for enhanced production when presented with appropriate stimuli. Increased PGI2 synthesis appears to be a result of an observed increase in arachidonic acid release and an activation of cyclooxygenase.