砂ネズミ脳毛細血管内皮細胞に対する放射線照射の影響

EFFECTS OF RADIATION ON CAPILLARY ENDOTHELIAL CELLS DERIVED FROM MONGOLIAN GERBIL BRAIN

　砂ネズミの脳毛細血管由来培養内皮細胞にX線照射を行い，その放射線生物学的パラメータおよび照射後の形態，第Ⅷ因子関連抗原（F VIII RAg）染色性，prostacyclin産生能の変化を調べ，他の部位の内皮細胞との差異について検討した。線量—効果曲線からこの内皮細胞の37％不活性化照射線量は190rad，準閾値線量は140rad，外挿値は1.9であった。照射24時閻以降において胞体や核の腫大化，空胞形成，巨細胞化などの形態変化が照射線量依存性にみられ，経時的に増大した。F VIII RAg染色性は，これら形態変化をきたした細胞において低下していた。Prostacyclin産生能は，照射後24時間では冗進し，72時間では有意な変化はなかった。以上の結果から，これまで報告された大血管由来培養内皮細胞の結果を比較すると，脳毛細血管内皮細胞は，大血管内皮細胞よりも放射線感受性が低い可能性が示唆された。また放射線照射による形態的，機能的変化はほぼ同様であると思われた。

Confluent monolayers of capillary endothelial cells derived from Mongolian gerbil brain were irradiated with a single exposure of x-rays, and their radiosensitivity and sequential changes in morphology, staining intensity for factor VIII-related antigen (F VIII RAg), and capacity to produce pro-stacyclin (PGI₂) were examined. The radiobip-logic parameters that characterized the dose-response survival curve for these cells were found to be n=1. 9, D_q=140 rad, and D_o= 190 rad. Mor-phologically, nuclear and cytoplasmic swelling, vacuolation of cytoplasm, and giant cell formation occured in a dose dependent manner after 24 hours from irradiation. Dereased staining intensity for F VIII RAg was observed in morphologically affec-ted cells. The capacity to synthesize PGI₂ was significantly enhanced at 24 hours, but less sig-nificant at 72 hours after irradiation.

The present data suggest that the radiosensi-tivity of brain capillary endothelial cells may be somewhat lower than that of endothelial cells originated from larger vessels, and that radiation induced morphological and functional changes in the brain capillary endothelial cells may be quan-tatively similar to the changes in endothelial cells of larger vessels.