Regional blood-to-tissue transport in an irradiated rat glioma model.
To assess vascular permeability in intracerebral grafts of the 36B-10, F-344 rat glioma following 20 Gy 137Cs whole brain irradiation, the blood-to-tissue transport constant, K, of [14C]-alpha-aminoisobutyric acid (AIB) was measured with quantitative autoradiography. Mean, 90th percentile, and 95th percentile values of K were determined in individual tumors and in treatment groups. In 15-day-old unirradiated control tumors, mean, 90th percentile, and 95th percentile values of K were, respectively, 11.3, 18.4, and 20.8 ml kg-1 min-1. In 15-day-old tumors irradiated on Day 14 (Day 1 postirradiation tumors) the K values were 5.9, 9.4, and 10.4, all of which were significantly less than the respective control values (P less than 0.01). In 16-day-old tumors irradiated on Day 14 (Day 2 postirradiation tumors), the K values were 10.8, 15.0, and 16.0, respectively, none of which was significantly different from control tumors. Mean K values for Day 2 vs Day 1 postirradiation tumors (10.8 vs 5.9) yielded P less than 0.05, but the 90th percentile and 95th percentile values for Day 2 vs Day 1 yielded 0.05 less than P less than 0.10. Separate experiments measured AIB and 86RbCl uptake in 36B-10 cells in vitro 1 and 2 days following 20 Gy irradiation to assess whether this radiation dose reduced the capacity of tumor cells to trap AIB or Rb+. Irradiation did not reduce the accumulation of either tracer, but rather was associated with an increased accumulation of AIB. Therefore, the AIB transport data suggest that vascular permeability and/or surface area decreases significantly in the day following 20 Gy irradiation and that this decrease reverses by the second day following irradiation.
D000621:Aminoisobutyric Acids / Q000378:metabolism; D000818:Animals; D001254:Astrocytoma / Q000098:blood supply / Q000532:radiotherapy*; D001345:Autoradiography; D001812:Blood-Brain Barrier / Q000528:radiation effects*; D001932:Brain Neoplasms / Q000098:blood supply / Q000532:radiotherapy*; D002199:Capillary Permeability / Q000528:radiation effects; D002588:Cesium Radioisotopes / Q000627:therapeutic use; D007700:Kinetics; D009368:Neoplasm Transplantation; D010953:Plasma Volume / Q000528:radiation effects; D051381:Rats; D011916:Rats, Inbred F344; D012413:Rubidium / Q000378:metabolism
D000621:Aminoisobutyric Acids; D002588:Cesium Radioisotopes; C100049:2-aminoisobutyric acid; D012413:Rubidium