HUMAN TYPE-II HYPERLIPOPROTEINEMIA ENHANCES PLATELET-COLLAGEN ADHESION IN FLOWING NONANTICOAGULATED BLOOD

We investigated the effects of high plasma lipid levels on platelet ad hesion and platelet thrombus formation in nonanticoagulated human bloo d on collagen fibrils at an arterial wall shear rate of 2600 seconds-1 . Nonanticoagulated blood was drawn directly at a flow rate of 10 mL/m in for 3 minutes from an antecubital vein of patients with type IIa (n =5) and type IIb (n=4) hyperlipoproteinemia over purified human type I II collagen fibrils that were positioned on a plastic coverslip in a p arallel-plate perfusion chamber. Results were compared with those obta ined in healthy individuals with normal lipid plasma levels (n=9). Blo od-collagen interactions were quantified by morphometry as platelet-co llagen adhesion, thrombus volume, and fibrin deposition. Platelet-coll agen adhesion in the two groups of patients was significantly higher t han in healthy individuals (70.7 [61.2 to 82.0] and 70.3 [66.4 to 81.0 ] in types IIa and IIb patients, respectively, versus 51.2 [44.5 to 68 .6] in control subjects; P<.05. All values are percent median [range]) . In contrast, the thrombus volume was similar in the three groups (11 .3 [8.0 to 13.0], 9.6 [6.4 to 15.3], and 10.2 [6.8 to 16.1] mum3/mum2 [range], respectively). Differences in fibrin deposition were not obse rved. Thus, it appears that platelet-collagen adhesion is augmented in patients with type IIa and IIb hyperlipoproteinemia, indicating that the process of thrombogenesis is hastened in these patients.