LIPID FLUIDITY MODULATES PLATELET-AGGREGATION AND AGGLUTINATION IN-VITRO

To determine the effect of altered membrane fluidity on platelet aggre gation/agglutination, fresh, washed human platelets were treated with A2C, a cyclopropyl fatty acid ester which is known to enhance mobility of intrinsic membrane bilayer constituents and increase membrane flui dity. Fluorescence polarization studies demonstrated A2C incubation ti me- and concentration-dependent increases in platelet membrane fluidit y (decreased fluorescence anisotropy). Preincubation with A2C was asso ciated with diminished collagen, thrombin and ristocetin-induced plate let aggregation/agglutination. Aggregation/agglutination was diminishe d by 93 +/- 5% for collagen (0.2 mg/ml), 53 +/- 3% for thrombin (1.0 U /ml) and 85 +/- 9% for ristocetin (1.1 mg/ml). These data suggest that membrane fluidity is involved in the regulation of platelet function.