SELENIUM HOMEOSTASIS IN THE CENTRAL-NERVOUS-SYSTEM OF THE RAT

These experiments have investigated selenium movement between blood an d CNS in anaesthetised rats. Each animal was surgically anaesthetised and the left femoral blood vessels cannulated for blood withdrawal and solute infusion. Each rat received 75-selenium as sodium selenite inf used in normal saline and experiments lasted between 5 minutes and 5 h ours during which blood samples were periodically taken. At terminatio n, the CNS was removed, regionally dissected and analysed with the pla sma samples for 75-Se radioactivity by gamma-counting. Data were analy sed by graphical analysis. Results showed unidirectional uptake of 75- Se into the CNS and regional differences were not found except for the hypothalamus. On average the CNS influx rate constant (K-in) Was abou t 7 +/- 1 x 10(-5) ml/min/g. Data suggest that the 75-Se most likely e ntered the CNS as a free ionic form.