Choline Pathways during Normal and Stimulated Renal Growth in Rats

during normal and stimutlated renal growNth. Choline in the kidney is utilized as a precuirsor for membrane synthesis via the choline kinase reaction. We in-vestigated choline phosphorylation dturing normal and stimulated renal growth. Rapidly growing neonatal rat kidneys contained relatively high levels of choline kinase activity (61 pmol phosphoryleholine/min per mg protein). Choline kinase activity and phosphorvl-choline production then fell gradually over the 1st mo of life; by 1 mo phosphorylcholine produiction was 34 pmol phosphorylcholine/min per mg protein. Choline kinase activity increased by 27 % (P < 0.001) in 28-day-old rats when renal growth was stimtulated by contra-lateral nephrectomy; the increase occuirred wvithin 2 h after suirgery. Thus, changes in the activity of this important enzyme in the initiation of membrane svn-thesis is associated both with normal renal develop-ment and with adaptation to nephron loss. The findings further stuggest that the cell membrane may be involved in the initiation of compensatory renal growth