放射線全身照射に伴うマウス血清と癌部局所照射に伴う担癌マウス血清の脂質過酸化物（TBA反応陽性物質）並びに脂肪酸組織の変動

Effects of irradiation on lipid peroxides of mouse serum, Ehrlich solid tumor-bearing mouse serum, which tomor cells were transplanted to the leg, and its tumor tissue were studied by a thiobarbituric acid (TBA) color reaction in the acetic acid condition with (Fe-TBA value) or without (TBA value) ferrous ammonium sulfate. TBA reactive substances were caluculated into the amount of malondialdehyde. Besides, fatty acid and lipid compositions were analyzed as a substrates. Irradiated samples were isolated at 3 days after irradiations. The TBA value of normal mouse serum was expressed 17nmoles/ml of serum, and Fe-TBA value gave 2.4-fold of the TBA value. Although an increase TBA value was not observed by whole-body irradiation, a significant increase of Fe-TBA value was measured, indicating 2.5-fold at 10Gy exposure compared with the normal Fe-TBA value, and 5.5-fold with the TBA value. The TBA value of tumor-bearing mouse serum was 14nmoles/ml as a low rate to that of normal serum, but the Fe-TBA value gave same magnification of that of normal one. The TBA value of tumor-bearing mouse serum was not changed by the local irradiation to the tumor region of leg, but the Fe-TBA value was increased 2.8 and 4.4 times at 10Gy and 20Gy exposures, respectively, comparing with the non-irradiated one, and 7.7 and 10.5 times with the TBA value, respectively. The TBA value of solid tumor homogenate exhibited 1.16nmoles/mg of protein, and the Fe-TBA value, pointed out 5 times as much as the TBA value. Both values slightly increased by the irradiation. These facts suggest that a shift of TBA value of serum hard to get, but Fe-TBA value of serum distinctly increases by the irradiation. The fatty acid composition of mouse serum lipids showed an increment of relative percentages of linoleic and arachidonic acids by the whole-body irradiation. The relative percentage of fatty acid compositon of lipids from solid tumor-bearing mouse serum was similar tendency to that of normal one, and the local exposure to the tumor part was not affected the each percentage. The percentage of high unsaturated fatty acid of tumor lipids similar to that of serum lipids, and a decrease of the percentage of arachidonic acid was accounted by the irradiation. In relative percentages of lipid compositions, the percentage of choleste rolester of serum lipids increased by the whole-body irradiation, and that of phospholipid fraction was not changed. In the case of tumor-bearing mouse serum lipids, an increment of the percentage of cholesterolester was obtained as compared with that of normal serum lipids, and this percentage decreased by the local irradiation to tumor part with an increment of the percentage of phospholipid. The percentage of phospholipid in tumor lipids had decreased by the irradiation. The facts suggest that a cause of the increased Fe-TBA value of tumor-bearing mouse serum by the irradiation to tumor is due to the release of peroxidizable phospholipid into serum from the damaged menbranes of tumor cells at large doses to exposure.

放射線照射に伴うマウス血清、大腿に移植形成させたEhrlich固定癌担癌マウス血清並びにその固型癌部組織の過酸化脂質の変化を酢酸酸性下、チオバルビツル酸発色法（TBA値）及びニ価鉄添加発色法（Fe-TBA値）で測定し、チオバルビツル酸反応陽性物質（TBARS）としてマロンジアルデヒド（MDA）に換算し評価した。合わせて過酸化反応基質としての脂肪酸組成と脂質組成を解析した。正常マウス血清のTBA値は本条件下で17nmoles MDA/ml値が得られ、Fe-TBA値はTBA値の2.4倍が得られた。全身照射によるTBA値の増加はみられなかったが、Fe-TBA値は半致死線量以上で明らかな増加がみられ、10Gy照射群で正常血清Fe-TBA値の2.5倍、TBA値に対し5.5倍が示された。担癌マウス血清のTBA値は14nmoles/mlで若干正常値に比し低値が得られたが、Fe-TBA値正常同様の倍率2.5倍値が示された。担癌マウス血清のTBA値は癌部10、20Gy局所照射により変化はみられなかったものの、Fe-TBA値は線量依存的に著しい増加がみられ、10Gyで対照値の2.8倍、20Gyで4.4倍値、TBA値に対し各7.7倍、10.5倍が得られた。固型癌部組織のTBA値は蛋白質当り1.16nmoles/mgが測定され、Fe-TBA値はTBA値の5倍であった。癌部照射でTBA値、Fe-TBA値とも若干の増加がみられた。これらのことから放射線照射によりTBA値の変化はみられ難いがFe-TBA値は増加することが示唆される。血清脂肪酸組成比では、全身照射によりリノール酸、アラキドン酸の増加がみられた。担癌血清脂肪酸組成比は正常のそれと同様であり、局所20Gy照射で変化はみられなかった。癌部組織の脂肪酸組成比においては、高級不飽和脂肪酸比は血清のそれと大差なかったが飽和脂肪酸比の変化が得られた。局所照射によりアラキドン酸比の減少がみられた。脂質組成比では、全身照射により血清のコレステロ－ル比の増加がみられたがリン脂質比は変化がみられなかった。担癌血清では正常に比し、コレステロールエステル比の増加がみられたが、局所照射により減少し、リン脂質比の増加が得られた。癌部組織の脂質組成比では照射によりリン脂質比の減少とトリグリセリド比の増加がみられた。これらのことから癌部局所照射により脂質過酸化反応の主たる基質としての過酸化物を含む細胞膜成分リン脂質の血清への流出が示唆され、これが癌部局所照射に伴う血清Fe-TBA値増加の一原因と考えられる。