RADIOPROTECTIVE EFFECTS OF A PROTEIN-FREE HEMODIALYSATE IN HUMAN EPIDERMIS

The accidental or therapeutic exposure of human skin to ionizing radia tion is known to cause the radiation syndrome with its various manifes tations. The aim of the study was to investigate the potential radiopr otective effects of the protein-free hemodialysate Actovegin. After ex posure to X-rays (single dose, 6 Gy), 70% of the cells died. In the pr esence of the hemodialysate, irradiation did not lead to cell death. I nstead a slight increase in cell number was observed. A 5-fold increas ed cell number was found after 6 days when the cells were treated with the hemodialysate alone. To elucidate molecular mechanisms of the obs erved biological effects the correlation between the expression of the epidermal growth factor receptor (EGFR) and the demonstrated growth a ctivation was investigated. Radiation alone resulted in a clear induct ion of EGFR, whereas the combination of irradiation and Actovegin trea tment led to a strong downregulation after 2 days. Thus, the hemodialy sate suppressed one of the radiation-induced effects. Further investig ations have to elucidate the role of other proteins which are involved in the signal transduction cascade of tyrosine kinases (e.g. Pas, Raf , MAP kinases) leading to the transcription factor AP-1 in response to radiation under Actovegin treatment.