title: Endothelial cell damage after gamma-irradiation in vitro: impaired uptake of alpha-aminoisobutyric acid.
abstract: The effects of gamma-irradiation with a cesium-137 source were assessed on endothelial cells isolated from bovine pulmonary arteries and maintained in culture. The radiobiologic parameters that characterize the dose-response survival curve for these cells, expressed as mean +/- SD were found to be n = 1.6 +/- 0.2, Dq = 71 +/- 13 rads, and Do = 161 +/- 35 rads, indicating a relatively low capacity of these cells to accumulate or repair radiation damage. Increasing doses of radiation led to decreasing uptake by endothelial cells of [14C]2-aminoisobutyric acid (AIB), a Na+-dependent and nonmetabolizable amino acid. A dose of 500 rads, which caused marked inhibition of cell survival, resulted in a 45% decrease in AIB uptake at 6 h and a 69% decrease in uptake at 24 h after irradiation. No morphologic abnormality was noted in these cells by light microscopy at 24 h after this dose of radiation. Bovine pulmonary artery fibroblasts, on the other hand, showed no significant impairment in uptake of AIB 24 h after exposure to doses of radiation as high as 5,000 rads. The uptake by endothelial cells of [14C]1-aminocyclopentane-1-carboxylic acid, an amino acid transported by a Na+-independent process, was not influenced by 5,000 rads of radiation. Our studies show that endothelial cells are sensitive to radiation and that impaired Na+-dependent uptake of AIB represents an early event in radiation damage to the endothelial cell.
mesh_terms: D000621:Aminoisobutyric Acids / Q000378:metabolism*; D000818:Animals; D001692:Biological Transport; D002417:Cattle; D004307:Dose-Response Relationship, Radiation; D004727:Endothelium / Q000528:radiation effects; D005720:Gamma Rays; D066298:In Vitro Techniques; D011651:Pulmonary Artery / Q000166:cytology / Q000378:metabolism / Q000528:radiation effects*
chemical_list: D000621:Aminoisobutyric Acids