Long-lasting depression of rabbit aortic prostacyclin formation by single-dose irradiation.

Male rabbits were exposed to a single irradiation dose of 1000-5000 rad when 12, 15, 16, and 17 months old and were killed when 18 months old (i.e., 1, 2, 3, and 6 months after irradiation). Even after this long interval after irradiation, abdominal aortic prostacyclin formation was significantly depressed, whereas the nonirradiated thoracic aortic segment exhibited no significant alteration in vascular PGI2 generation. The data show that the severe decrease in PGI2 synthesis was not caused by deendothelialization induced by irradiation alone. The data support the view that a deterioration in the prostaglandin system regulating hemostatic balance is an important determinant in the development of radiation-induced vasculopathy.