Structural changes of liver microsomes in rat during neonatal life: influence on the glucuronidation rates of various substrates.
The Vmax of the membrane bound UDP-glucuronosyltransferase (UDP-GT) towards group 1 substrates (4-nitrophenol, 2-naphthol) was particularly higher in young rats than in adults. On the contrary, activity towards group 2 substrates such as borneol or testosterone was not detectable in fetus liver. The developmental pattern of UDP-GT was related to changes in lipid composition of microsomes, namely in the content in lysophosphatidylcholine which rose at birth. The phospholipid-cholesterol molar ratio also increased 2 fold from the 16th day of fetal life to the 4th day after birth. Measurement of the steady state anisotropy of 1,6-diphenyl-1,3,5-hexatriene (DPH) as well as determination of the order parameter S and the rotation cone angle of the fluorescent probe strongly suggested an increase in membrane fluidity in rat liver microsomes during ontogenesis.
D000818:Animals; D002784:Cholesterol / Q000378:metabolism; D014453:Glucuronosyltransferase / Q000378:metabolism*; D008099:Liver / Q000196:embryology / Q000254:growth & development*; D008244:Lysophosphatidylcholines / Q000378:metabolism; D008560:Membrane Fluidity; D008563:Membrane Lipids / Q000378:metabolism*; D008862:Microsomes, Liver / Q000378:metabolism*; D010743:Phospholipids / Q000378:metabolism; D051381:Rats; D013379:Substrate Specificity; D014783:Viscosity
D008244:Lysophosphatidylcholines; D008563:Membrane Lipids; D010743:Phospholipids; D002784:Cholesterol; D014453:Glucuronosyltransferase