title: Vascular response to fractionated irradiation in the rat lung.
abstract: The effects of fractionated hemithorax irradiation on normal lung tissue were examined by measuring changes in the vascular permeability surface area product (PS) and relative lung blood flow in Sprague-Dawley rats. The rats received five daily fractions per week of either 3.0 or 4.0 Gy for 4 weeks to the left lung. Between 3 and 5 weeks after the start of irradiation, the average PS was approximately 50% above normal for the group of rats that received 3.0 Gy/day and 200-300% above normal in the group of rats that received 4.0 Gy/day. Treatment with cyproheptadine, indomethacin, or theophylline had no effect, but treatment with dexamethasone significantly reduced PS to near normal levels. Left-to-right blood flow ratios in the group of rats that received 3.0 Gy/day decreased to 66% of normal levels by 4 weeks. In the group of rats that received 4.0 Gy/day, blood flow decreased to 46% of normal levels by 4 weeks. Treatment with dexamethasone maintained normal blood flow until the drug dose was reduced. These results agree with earlier studies using single-dose irradiation and indicate that the methods used to measure PS and blood flow are sensitive at low doses.
authors.affiliation: Department of Radiation Oncology, University of Washington Medical Center, Seattle 98195.
authors.forename: L M
authors.initials: LM
authors.lastname: Peterson
authors.forename: M L
authors.initials: ML
authors.lastname: Evans
authors.forename: K L
authors.initials: KL
authors.lastname: Thomas
authors.forename: M M
authors.initials: MM
authors.lastname: Graham
mesh_terms: D000818:Animals; D002199:Capillary Permeability / Q000187:drug effects / Q000528:radiation effects*; D003533:Cyproheptadine / Q000494:pharmacology; D003907:Dexamethasone / Q000494:pharmacology; D007213:Indomethacin / Q000494:pharmacology; D008168:Lung / Q000098:blood supply / Q000187:drug effects / Q000528:radiation effects*; D008297:Male; D011652:Pulmonary Circulation / Q000187:drug effects / Q000528:radiation effects*; D051381:Rats; D011919:Rats, Inbred Strains; D013047:Specific Pathogen-Free Organisms; D013806:Theophylline / Q000494:pharmacology
chemical_list: D003533:Cyproheptadine; D003907:Dexamethasone; D013806:Theophylline; D007213:Indomethacin