[Inhibition of lipoxygenase activity reduces radiation-induced DNA fragmentation in lymphocytes]. / Ingibirovanie lipoksigenaznoi aktivnosti snizhaet indutsirovannuiu radiatsiei fragmentatsiiu DNK limfotsitov.

Lypoxygenase activity of lymphocytes towards exogenous substrate linolic acid and the level of endogenous arachidonate metabolite 15-HETE are increased within 6 h and decreased below the control level at 24 h after 1 Gy X-ray irradiation of Wistar rats. DNA fragmentation is stimulated both in vivo within 12 h and during in vitro incubation of lymphocytes, obtained 3 h following irradiation. DNA analysis by agarose gel shows that DNA fragments are multiples of the 200 base pair unit. When 20 microM nordihydroguayaretic acid, a selective inhibitor of arachidonate lypooxidation, was added to the incubation medium, DNA fragmentation was observed to be significantly less, especially at the early steps of incubation.

[Lipoxygenase activity and 15-hete content of rat spleen lymphocytes after exposure to ionizing radiation]. / Lipoksigenaznaia aktivnost' i soderzhanie 15-hete v limfotsitakh selezenki krys pri deistvii ioniziruiushchei radiatsii.

Pretreatment of rat spleen lymphocytes with 0.5 mM A23187 had no influence on the prostaglandins E2 and F2 alpha content, but was followed by the increasing of both 15-HETE and leukotriene B4 levels. Lypoxygenase activity of lymphocytes towards exogenous substrate linoleic acid was increased within 3-12 h after 1 Gy irradiation and decreased below the control level at 24 h. The changes of lypoxygenase activity correlate with that of 15-HETE content. Additional incubation of the cells, obtained at 3 h after irradiation, was followed by the intensification of the chromatin internucleosomal fragmentation and low-molecular DNA fragments accumulation. When 20 mM nordihydroguaiaretic acid, a selective inhibitor of arachidonate lipooxidation, was added to the incubation medium, DNA fragmentation was observed to be significantly less, especially at the early steps of incubation. These results suggest, that metabolites like H(P)ETE are early endogenous mediators of radiation-induced spleen lymphocytes apoptosis.