Goda F, O'Hara J A, Rhodes E S, Liu K J, Dunn J F, Bacic G, Swartz H M
Department of Radiology, Dartmouth-Hitchcock Medical Center, Hanover, New Hampshire 03755, USA.
Cancer Res. 1995 Jun 1;55(11):2249-52.
Electron paramagnetic resonance oximetry was used to measure the partial pressure of oxygen (pO2) in two types of tumor in vivo in C3H/HeJ mice. The pO2 in MTG-B (high hypoxic fraction) and RIF-1 (low hypoxic fraction) tumors was monitored prior to and at several time points after a single dose of X-ray irradiation (up to 7 days after treatment). Initial values of pO2 in RIF-1 (8.7 +/- 1.1 mm Hg; n = 14) were higher than that of pO2 in MTG-B (3.3 +/- 0.5 mm Hg; n = 19). The pO2 in both types of unirradiated tumors decreased slowly with tumor growth. Irradiation of tumors had a two-phase effect on pO2: an initial sharp decrease in pO2, followed by slow reoxygenation. After a 20-Gy radiation dose, the pO2 was 2.2 +/- 0.5 mm Hg at 6 h [significantly lower (P < 0.0001) than in control] and 3.2 +/- 0.5 mm Hg at 48 h [significantly higher (P < 0.02) than in control] in MTG-B, and 5.4 +/- 1.2 mm Hg at 24 h and 8.2 +/- 1.0 mm Hg at 72 h in RIF-1. The time course for these changes in pO2 was found to be independent of the doses in use in this study (10, 20, and 40 Gy). The occurrence of radiation-induced changes in pO2 and the different time courses of these changes suggest that repeated monitoring of pO2 in tumors during treatment could be used to enhance the efficacy of clinical treatments.
采用电子顺磁共振血氧测定法测量C3H/HeJ小鼠体内两种肿瘤的氧分压（pO2）。在单次X射线照射前及照射后的几个时间点（治疗后长达7天）监测MTG-B（高乏氧分数）和RIF-1（低乏氧分数）肿瘤的pO2。RIF-1肿瘤的pO2初始值（8.7±1.1 mmHg；n = 14）高于MTG-B肿瘤的pO2初始值（3.3±0.5 mmHg；n = 19）。两种未照射肿瘤的pO2均随肿瘤生长而缓慢下降。肿瘤照射对pO2有两阶段影响：pO2最初急剧下降，随后缓慢复氧。给予20 Gy辐射剂量后，MTG-B肿瘤在6小时时pO2为2.2±0.5 mmHg[显著低于对照组（P < 0.0001）]，在48小时时为3.2±0.5 mmHg[显著高于对照组（P < 0.02）]；RIF-1肿瘤在24小时时为5.4±1.2 mmHg，在72小时时为8.2±1.0 mmHg。发现pO2这些变化的时间进程与本研究中使用的剂量（10、20和40 Gy）无关。辐射诱导的pO2变化的发生以及这些变化的不同时间进程表明，在治疗期间重复监测肿瘤中的pO2可用于提高临床治疗效果。
