Vitamin E and the peroxidizability of erythrocyte membranes in neonates.
We showed the increased susceptibility of neonatal biomembranes to oxidation by a kinetic analysis using an azo compound as a free-radical initiator and red blood cell (RBC) ghosts as a model membrane. When the RBC ghosts were oxidized, oxygen consumption was suppressed during the induction period in which membrane tocopherol was consumed at a constant rate, while increased oxygen uptake was observed after the tocopherol was exhausted. The total tocopherol content was similar in cord, maternal, and adult RBC ghosts, and there were no differences in the induction period (tinh) among the three types of ghosts. While the oxygen uptake rate during the induction period (Rinh) was similar in cord and adult ghosts, the rate in the subsequent phase (Rp) was considerably faster in the cord ghosts. Fatty acid analysis in the membrane lipids showed that the active bisallylic hydrogen (active H) content was greater in cord ghosts than in adult ghosts. The active H content closely correlated with the Rp, but did not with the Rinh. The kinetic chain length (KCL), i.e., the ratio of the rate of propagation to that of initiation, was calculated from Rp and tocopherol consumption rate and KCL values were higher in cord ghosts than in adult ghosts. The faster Rp and the higher KCL of the cord ghosts were attributable to a greater active H content rather than to the tocopherol content.
Miyake
M
M
Department of Pediatrics, Osaka Medical College, Japan.
Miki
M
M
Yasuda
H
H
Ogihara
T
T
Mino
M
M
D000328:Adult; D000578:Amidines / Q000494:pharmacology; D004910:Erythrocyte Membrane / Q000378:metabolism*; D005227:Fatty Acids / Q000378:metabolism; D005260:Female; D005312:Fetal Blood; D005609:Free Radicals; D006461:Hemolysis / Q000187:drug effects; D006801:Humans; D006859:Hydrogen / Q000097:blood; D007231:Infant, Newborn / Q000097:blood*; D007700:Kinetics; D015227:Lipid Peroxidation / Q000187:drug effects*; D008054:Lipid Peroxides / Q000096:biosynthesis; D008297:Male; D008563:Membrane Lipids / Q000378:metabolism; D010100:Oxygen / Q000378:metabolism; D011247:Pregnancy; D014810:Vitamin E / Q000097:blood* / Q000502:physiology
D000578:Amidines; D005227:Fatty Acids; D005609:Free Radicals; D008054:Lipid Peroxides; D008563:Membrane Lipids; D014810:Vitamin E; C046728:2,2'-azobis(2-amidinopropane); D006859:Hydrogen; D010100:Oxygen