Irradiation Effects upon Ischemic Regenerating Rat Liver Cells

Starch particles injected into the arterial and portal systems of the liver of the rat caused a temporary blockage of the liver circulation and consequent hypoxia in the liver cells. In the regenerating liver this resulted in a 30-40% decrease of thymidine incorporation into DNA, when analysed 1.5 hours after injection. Irradiation-induced cell damage, evaluated by thymidine incorporation 1.5 hours after irradiation with a single dose of X-rays, was not ameliorated by the ischemic condition. It is suggested that this depends on an inhibited nucleotide metabolism and DNA synthesis leading to an additive metabolic hypoxic effect of the starch particles on radiation damage. An equal level of thymidine incorporation, however, was found in an ischemic and a non-ischemic group of animals 16 hours after irradiation. In this case the liver cells in the ischemic group had overcome the additional inhibition of DNA synthesis caused by temporary hypoxia.