Automated microdensitometry and protein assays as a measure for platelet adhesion and aggregation on collagen-coated slides under controlled flow conditions.

A parallel-plate perfusion cell was developed for the in vitro study of platelet adhesion and aggregation. Two collagen-coated slides were exposed simultaneously to citrated blood under laminar and controlled flow conditions. The extent of the surface covered with platelets (adhesion) and platelet accumulations (aggregation) greater than about 5 micrometers in height was determined en face by automated microdensitometry of the fuchsin-stained collagen slides. The global measurement of deposited platelet protein per unit of surface was measured with a modified Lowry technique. Correlation among different parameters used to estimate the mass density on the slides, i.e., platelet number, amount of protein, and extent of platelet aggregation, is demonstrated. Acetylsalicylic acid at 100 microM decreased platelet aggregation without affecting adhesion. The new parallel-plate perfusion system offers rapid quantitation of platelet adhesion and aggregation after exposure to flowing blood.