Rheological properties and membrane fluidity of red blood cells and platelets in primary hyperlipoproteinemia.

Lipid fluidity of the erythrocyte membrane and intact platelets was examined in 32 male patients affected by types IIA, IIB and IV primary hyperlipoproteinemia and 15 control subjects. Lipid fluidity was determined by fluorescence polarization using two probes: DPH and TMA-DPH which are localized in different lipid areas of the cell membrane. Classical haemorheological tests were also performed including plasma viscosity, whole blood viscosity and erythrocyte aggregation. As compared to a control group, plasma viscosity and whole blood viscosity at low shear rate was significantly increased in types IIB and IV, but not in type IIA patients. In contrast, the increase in erythrocyte aggregation was significant in all HLP types. Concerning lipid fluidity, the results recorded with red cells and platelets were not significantly different for type IIA HLP compared to the control group. In contrast, erythrocyte membranes from patients with types IIB and IV HLP had a significantly higher level of fluidity in lipid regions characterized by TMA-DPH. Using DPH as a fluorescent probe, identical results were only noted in type IIB patients. Regarding intact platelets of IIB and IV patients, an increase in lipid fluidity was noted for two fluorescent probes. These findings suggest that HLP associated erythrocyte and platelet fluidity alterations are not related to hypercholesterolemia but to the triglyceride level.