Superhigh dose effects of 6 MeV EB irradiation on Ca2+ and Mg2+ contents in rat brain

The work is to study possible mechanisms of radiation injuries to brain by observing Ca2+ and Mg2+ contents in electron beam irradiated rat brain. Sprague-Dawley rats were irradiated with a single dose of 10 Gy, 20 Gy or 30 Gy by 6 MeV electrons. On different days after the irradiation, Ca2+ and Mg2+ contents in whole brain of the rats were measured by direct-reading plasma spectrography, and the brain water content was calculated with wet-dry weight formula. In comparison to the control groups, the total tissue water and Ca2+ content in brain of all the irradiated rats increased, while the Mg2+ content in brain decreased. The of Ca2+ content increased markedly (p<0.05) 24h after the irradiation, and the Mg2+ content decreased significantly (p<0.05) 7d after the irradiation. The content changes became severe with increasing dose. Discusions are made on mechanisms of radiation induced brain injuries based on observations of the Ca2+ and Mg2+ contents changes in the rat brain. (authors)