QUANTIFICATION OF THE PASSIVE MECHANICAL-PROPERTIES OF THE RESTING PLATELET

Sudden coronary artery occlusion is one of the leading causes of death . Several in vitro models have been used to study the relationship bet ween hemodynamic forces and platelet function. However, very few in vi vo studies exist that fully explore this relationship due to the lack of theologic data for the platelet. For this purpose, micropipette asp iration techniques were used in the present study to determine the mec hanical properties of platelets. The data were analyzed by two mathema tical models: (1) an erythrocyte-type membrane model which yielded a p latelet shear modulus of 0.03 +/-0.01 dyn cm(-1) (mean+/-SD) and a vis cous modulus of 0.12 +/-0.04 dyn a cm(-1). (2) An endothelial-type cel l model which approximated the platelet Young's modulus to be 1.7+/-0. 6 x10(3) dyn cm(-2) with a viscous modulus of 1.0+/-0.5 x 10(4) dyn s cm(-2). The endothelial-type cell model more accurately describes the mechanics occurring at the micropipette tip and permits more appropria te assumptions to be made in quantifying the theologic properties of a platelet. Results from this study can be integrated into numerical mo dels of blood how in stenosed coronary arteries to elucidate the impac t of local hemodynamics on platelets and thrombus formation in coronar y artery disease. (C) 1998 Biomedical Engineering Society.