The effect of aging (2-14 months) and total body irradiation (5.7 Gy of gamma radiation) on liver regeneration was investigated in rats 30 h after partial hcpatcctomy. Exposure of rats to irradiation 30 min before partial hepatectomy caused latent injury in the remaining liver cells. During the course of liver regeneration this became manifested as a delay in increasing the nucleic acid concentration and content and liver weight and, furthermore, as inhibition of the increase in the mitotic index and ccllularity and pronounced increase in the frequency of chromosome aberrations in the postmetaphase. The pattern of age-related changes during liver regeneratin was the same as that after irradiation, so that the differences between irradiated and nonirradiated animals became smaller with age.
Gamma irradiation with a dose of 5.7 Gy within 30 min before partial hepatectomy (PHE) caused latent damage in the intact rat liver. This was expressed in the course of proliferation induced in the liver remnant by inhibition of the regenerative process, which was indicated by a decreased mitotic index and cellularity, an increased ratio of metaphases/prophases and a high chromosomal aberration frequency. The preparation of essential phospholipids (ESSENTIALE) that was injected in a dose of 360 mg/kg (i.p.) either 24 h before irradiation or 30 min after irradiation or repeatedly before and after irradiation, markedly stimulated the process of liver regeneration after PHE in both nonirradiated and irradiated rats. It moderated all the alterations induced by irradiation, especially changes in cellularity. The most effective was the repeated administration of ESSENTIALE whereas its single administration before irradiation was more effective than that after irradiation. Our results suggest that ESSENTIALE has not only a stabilizing effect on cell membranes, but also mitigates damage of genetic material induced by irradiation.