RESUMEN
Twenty male albino rats, weighing 150 +/- 10 gm were divided into experimental and control groups of equal number. Sodium pentobarbitone [30 mg/kg body weight] was injected intraperitoneally to produce general anaesthesia in all the rats. Heads of the test rats were exposed to gamma irradiation [558.6 rads in a single dose]. Tissues from the precental gyrus of the cerebrum of all the animals were taken out immediately and processed partly for neurohistological stains and partly for biochemical estimations. Microscopic examination revealed hydropic degeneration of the nerve cells. Biochemical estimation established increased sodium level in the nervous tissue without affecting potassium concentration. Alteration in sodium was considered to be an important criterion in acute damage of nervous tissue and also responsible for hydropic degeneration due to irradiation