Low-Level X-Radiation-Induced Vascular Alterations in Normal and DMBA-Treated, Tumor-Bearing Cheek Pouch Epithelium of Syrian Hamsters

Abstract

Studies were conducted to examine late changes in vascular volume and vascular perfusion of normal and tumor-bearing Syrian hamster cheek pouches, treated either with DMBA, repeated low-level x radiation, or DMBA + x radiation. Hamsters received once-weekly 20-R exposures to the head and neck for 17 consecutive weeks. During weeks 1 to 5 and 7 to 11 of irradiation, 0.1% DMBA was applied to right cheek pouches twice weekly. Thirty-nine weeks after initial treatment, animals were injected intravenously with /sup 51/Cr-labeled erythrocytes to determine cheek pouch blood volume and /sup 86/RbCl to determine the vascular perfusion of cheek pouch tissues. Following excision of tumors and pouches, /sup 51/Cr and /sup 86/Rb activities and histopathologic changes were assessed. Irradiated animals had no tumors, 53% of the DMBA-treated animals had tumors, and 75% of the DMBA + radiation-treated animals had tumors. Irradiated cheek pouches had increased blood volume, and DMBA-treated tumor-bearing pouches had increased blood volume and perfusion. DMBA + radiation-treated tumor-bearing pouches had increased blood volume similar to that seen in irradiated pouches and increased blood perfusion similar to that seen in DMBA-treated, tumor-bearing pouches. While the presence of DMBA-induced tumors was related to changes in vascular perfusion in all groups,more » low-level x radiation appeared to alter changes in blood volume caused by DMBA or DMBA-induced tumors.« less