Change in ascorbate radical production in an irradiated experimental tumor with increased tumor size.
We have reported that ascorbate radical (Asc.-) could serve as an indicator of the amount of hydroxyl radical and superoxide produced by irradiation in vivo. Using this method, we investigated the relationship between tumor size and Asc.- production after irradiation (10 Gy) and between tumor size and the radical-scavenging ability of WR-2721 (300 mg/kg). Asc.- was measured in normal muscle and SCC-VII tumors transplanted into mice (n = 6). In tumors, the increase in Asc.- significantly decreased with increasing tumor size (r = -0.483; P < 0.05). The increase in Asc.- production after irradiation was more inhibited by WR-2721 in normal muscle tissue than in tumor tissue at various sizes. In tumors, the increase in Asc.- was less inhibited by WR-2721 with increasing tumor size. These results demonstrate that the increase in radical production after irradiation and drug distribution decreased with increasing tumor size and that WR-2721 has excellent differential protection. This method is expected to measure changes in the amounts of local hydroxyl radical and superoxide modified by a change of tumor environment or drug administration.
Isoda
H
H
Department of Radiology, Kansai Medical University, Osaka, Japan.
Akagi
K
K
Murata
T
T
Aoki
Y
Y
Ikeda
S
S
Tanaka
Y
Y
Kihara
T
T
Ikeda
M
M
D004999:Amifostine / Q000494:pharmacology; D000818:Animals; D001205:Ascorbic Acid / Q000378:metabolism*; D002294:Carcinoma, Squamous Cell / Q000378:metabolism* / Q000473:pathology / Q000532:radiotherapy; D008297:Male; D051379:Mice; D008809:Mice, Inbred C3H; D018482:Muscle, Skeletal / Q000378:metabolism* / Q000528:radiation effects; D011837:Radiation-Protective Agents / Q000494:pharmacology
D011837:Radiation-Protective Agents; D004999:Amifostine; D001205:Ascorbic Acid