CHANGES IN SPECIFIC AMINO-ACID-RESIDUES AND NA-ATPASE ACTIVITY IN CELL-MEMBRANES OF RAT CEREBRAL-CORTEX BY LOW-DOSE X-IRRADIATION(,K+)

This study examines the influence of low dose X-irradiation on the str ucture and transport function of cell membranes of rat cerebral cortex . We found that unlike high dose irradiation which promotes membrane d amage, low dose irradiation stimulates the SH group of membrane protei ns and enhances the ability to control the membrane transport mechanis m as reflected by an increase in Na+, K+-ATPase activity. The concentr ation of cysteine (Cys) significantly increased at 25-100 cGy and the concentration of cystine (Cys-Cys) significantly decreased at 25 cGy. It showed no dose dependent changes in tyrosine (Tyr), phenylalanine ( Phe) and glycine (Gly). Similarly phospholipid and cholesterol levels were unchanged. Na+, K+-ATPase activities significantly decreased at 1 00 cGy or higher but significantly increased at doses of 25 and 50 cGy .