The fusion radiosensitivity of differentiating chick embryo myoblasts in vitro is not determined by the plasma membrane

Protective effects of insulin-like growth factor-I on the decrease in myogenic differentiation by ionizing radiation

PURPOSE

The aim of the work is to evaluate the effects of insulin-like growth factor-1 (IGF-1) on the decrease in myotube formation induced by ionizing radiation.

MATERIALS AND METHODS

We induced C2C12 cells to a myogenic linage following X-ray irradiation at 2 and 4 Gy. Myogenic differentiation was estimated using immnocytochemical staining with anti-myosin antibody, and the anti-myosin antibody positive areas, the total number of nuclei, the number of nuclei included in multinucleated myotubes per field, and the myotube formation ratio were analyzed.

RESULTS

In the myogenic differentiation in the presence of IGF-1, the decrease in anti-myosin antibody positive areas, the nuclei included in myotubes, and the myotube formation ratio induced by X-ray irradiation at 2 Gy was restored to control levels.

CONCLUSIONS

The addition of IGF-1 protected against the decrease myotube formation induced by X-ray irradiation at 2 Gy. Since X-ray irradiation at 2 Gy is usually used for multi-fractionated irradiation in radiotherapy, our findings suggest that IGF-1 could be useful to protect against impairment of muscle repair induced by therapeutic dose radiation.

Recent developments in the radiobiology of cellular membranes

We have reviewed the literature on cellular membrane radiobiology over the last ten years and, in particular, report on the development of rapid techniques used to identify damage soon after irradiation. It is clear that damage can now be quantified after low doses, and further refinements can be expected. From the work summarised, it would appear that changes to membranes at low doses may occur soon after damage to other important macromolecules by intercommunicating processes. We believe that there now exists a variety of rapid methods of measuring deposition of damage in vital macromolecules, such as cellular membranes and DNA, which can give a fuller picture of the overall effects of radiation and lead to predictions of eventual cellular mortality.