title: Irradiation decreases vascular prostacyclin formation with no concomitant effect on platelet thromboxane production.
abstract: Effects of irradiation on vascular tissue include endothelial cell degeneration, vasoconstriction, and thrombus formation. The effect of irradiation on the in-vitro production of prostacyclin (PGI2) was evaluated, since it is a potent antithrombotic metabolite and vasodilator. After a single dose of 200 rad, umbilical artery PGI2 levels were much decreased when estimated both be bioassay and by evaluation of the stable end-product of PGI2, 6-keto-prostaglandin in Fl alpha. The mean PGI2 production in control tissue was 0.94 +/- 0.14 (1SEM) ng/mg vascular tissue compared with 0.18 +/- 0.07 ng/mg in paired irradiated vessels (p less than 0.001). However, irradiation had no effect on platelet thromboxane formation in a dose rage of 200-2000 rad. Since radiotherapy is routinely administered for the whole period of therapy in daily dose fractions similar to the in-vitro experimental dose used in this study, recovery of vascular PGI2 production may be inhibited for the total period of radiotherapy.
mesh_terms: D001792:Blood Platelets / Q000378:metabolism*; D001808:Blood Vessels / Q000378:metabolism / Q000528:radiation effects*; D004727:Endothelium / Q000378:metabolism / Q000528:radiation effects; D011464:Epoprostenol / Q000096:biosynthesis*; D005260:Female; D006801:Humans; D009131:Muscle, Smooth, Vascular / Q000378:metabolism / Q000528:radiation effects; D011453:Prostaglandins / Q000096:biosynthesis*; D011829:Radiation Dosage; D013929:Thromboxane B2 / Q000096:biosynthesis*; D013931:Thromboxanes / Q000096:biosynthesis*
chemical_list: D011453:Prostaglandins; D013931:Thromboxanes; D013929:Thromboxane B2; D011464:Epoprostenol