Grdina D J, Sigdestad C P, Jovonovich J A
Cancer Clin Trials. 1980 Summer;3(2):149-54.
The effects of misonidazole on fibrosarcome FSa) tumor cells irradiated in situ were determined for tumor cell subpopulations isolated by density gradient centrifugation. Mice (C3HF/Kam) bearing FSa tumors in the flank were injected i.p. with misonidazole (1 mg/g) 20 minutes before irradiation with various doses from a 137Cs gamma source. Immediately after irradiation single-cell suspensions were prepared and tumor cell subpopulations were separated by density gradient centrifugation. Clonogenicity for selected tumor cell populations was determined using the lung colony assay. It has been reported previously that following in situ irradiation, the cell population collected at a density of 1.08g/cm3 contains a relatively large fraction of sensitive (oxic) cells. It has also been reported that the cell population collected at 1.14 g/cm3 behaves as a chronically hypoxic cell population with respect to radiation response (Do = 400 rads; n = 5.2). Following injection of misonidazole, both the Do and the n of the resultant survival curve were reduced (Do = 306 rads; n = 0.5) indicating that the drug was effective in radiosensitizing this chronically hypoxic cell population. It also effectively sensitized the small fraction of resistant cells present in the cell population banding at 1.08 g/cm3. This was evidenced by a change in the survival curve parameters calculated for the terminal region of the curve: drug, Do = 279 rads, n = 0.3; no drug, Do = 459 rads, n = 1.2. Similar sensitization was found on unseparated control cells (USC). No cytotoxic effects from misonidazole were observed due to the short time interval in which the FSa was exposed to the sensitizer.
对于通过密度梯度离心分离得到的肿瘤细胞亚群，测定了米索硝唑对原位照射的纤维肉瘤FSa肿瘤细胞的影响。将携带位于胁腹的FSa肿瘤的小鼠（C3HF/Kam）腹腔注射米索硝唑（1mg/g），20分钟后用137Csγ源进行不同剂量的照射。照射后立即制备单细胞悬液，并通过密度梯度离心分离肿瘤细胞亚群。使用肺集落试验测定选定肿瘤细胞群体的克隆形成能力。先前有报道称，原位照射后，密度为1.08g/cm³收集的细胞群体含有相对较大比例的敏感（有氧）细胞。也有报道称，密度为1.14g/cm³收集的细胞群体在辐射反应方面表现为慢性缺氧细胞群体（Do = 400拉德；n = 5.2）。注射米索硝唑后，所得存活曲线的Do和n均降低（Do = 306拉德；n = 0.5），表明该药物对使这个慢性缺氧细胞群体产生放射增敏作用有效。它还有效地使密度为1.08g/cm³条带的细胞群体中存在的一小部分抗性细胞产生增敏作用。这通过计算曲线末端区域的存活曲线参数变化得到证明：用药组，Do = 279拉德，n = 0.3；未用药组，Do = 459拉德，n = 1.2。在未分离的对照细胞（USC）上也发现了类似的增敏作用。由于FSa暴露于增敏剂的时间间隔较短，未观察到米索硝唑的细胞毒性作用。
