Phosphate (P32) Exchange in Brain Phospholipids in vivo and in vitro.

Abstract

P32 turnover of rat brain homo-genates, as evidenced by specific activity rise on incubation with p32O4 =, is complete in acid soluble and lipid fractions within 20 min. Total lipid specific activity reaches 0.1% of inorganic phosphate, but separate fractions range from 2% (lipoprotein) to 0.02% (methanol, choline lipids). In vivo, by contrast, P32 uptake by brain lipids was much higher at 20 hrs. than at 4 and specific activities of all the lipid fractions, alike, rose to almost 10% of the presumable precursor (delta 7) level. Factors involved in these findings are discussed.