Presented at the Neonatal Society 2001 Summer Meeting.
Kurlak LO, Stephenson TJ, Broughton-Pipkin F
School of Human Development, Queen’s Medical Centre, Nottingham, NG7 2UH, UK
We have previously shown that membrane fluidity is greater in cord than adult platelets (1). Phospholipid structure incorporates fatty acyl chains which can influence membrane fluidity and function. We investigated whether the fatty acid profile differs between adults and neonates and whether it has an influence on platelet membrane fluidity.
Washed platelets were prepared from adults (n=19),full term umbilical cord (n=52),and snap frozen in liquid N2. Thawed samples were sonicated and extracted using chloroform: methanol (2:1). Phospholipids were separated by differential solvent extraction on Sep-Pak Silica cartridges(2)and their fatty acid methyl esters were identified using Gas Chromatography-Mass Spectrometry. Membrane fluidity was assessed by measurement of fluorescence anisotropy using TMA-DPH and DPH fluorophores.
(n.d. = not detected)
In a subset of neonates (n=28) studied, there was no direct correlation between fatty acid levels and fluorescence anisotropy.
The difference in fatty acid composition in the neonates may reflect the accretion pattern in late pregnancy, when accumulation rates are higher for longer chain fatty acids relative to shorter fatty acids. Total antioxidant capacity increases towards term therefore membrane fluidity may be more affected by increased free radical -induced lipid peroxidation. This may also explain the greater variability in the neonatal samples.
References
1. Kurlak LO, Stephenson TJ, Broughton Pipkin F. J Physiol 1999;517.P:7P.
2. Hamilton JG, Comai K. Lipids 1988;23(12):1146-1149.