PLATELET MEMBRANE FLUIDITY AND PLASMA MALONDIALDEHYDE LEVELS IN ALZHEIMERS DEMENTED PATIENTS WITH AND WITHOUT FAMILY HISTORY OF DEMENTIA

Platelet membrane fluidity (PMF) was measured with three different flu orescent probes, 1,6-diphenyl-1,3,5-hexatriene (DPH), 1-(4-trimethylam moniumphenyl)-6-phenyl-1 triene (TMA-DPH), 3-(p-phenyl-1,3,5-hexatrien yl)phenyl-proprionic acid (DPH-PA), which labeled different parts of t he bilayer (the hydrophobic core and the positively and negatively cha rged regions, respectively) in Alzheimer's disease (AD)patients with a nd without a family history of dementia, and in a control group. In su pport of earlier findings in the literature, significantly increased P MF was found by the application of DPH in both groups with AD. The use of the fluorescence probe TMA-DPH, however, revealed no differences b etween the groups. In contrast, significant rigidffication was observe d with DPH-PA, but only in the AD group with a positive family history of dementia. The plasma malondialdehyde levels appeared to be similar in each group. Our findings are discussed in light of the controversi es regarding the value of PMF measurements