Translocation of hyaluronic acid in cell surface of cultured mammalian cells after X-irradiation and its recovery by added adenosine triphosphate

To investigate the mechanism of radiation-induced decrease in cell electrophoretic mobility and its recovery by added adenosine triphosphate, specific enzymes and buffer solutions of different ionic strength were utilized. Decrease in the mobility of irradiated cells was detected only with the buffer solution of ionic strengths higher than 0.100. In this range of ionic strengths, removal of hyaluronic acid from cell surface by hyaluronidase had no effect on the electrophoretic mobility of irradiated cells, while the enzyme treatment resulted in 27% mobility reduction in non-irradiated cells. The removal of sialic acid and chondroitin sulfate by their specific enzymes resulted in the similar decrease in mobility either in irradiated and non-irradiated cells. These results suggest that the X-ray induced translocation of hyaluronic acid from the peripheral zone of 0–7.5 Å into the deeper zone of about 10–17 Å, if we use the Debye-Hückel's thickness of ion atmosphere for an approximate estimate of effective depth of electrokinetic plane of shear. Hyaluronic acid reappeared to the peripheral zone by the subsequent incubation after small dose irradiation, or by the addition of 1 mM adenosine triphosphate with Ca²⁺.