Quantitative radioisotopic measurement and scanning electron microscopic study of platelet adherence to a collagen-coated surface and to subendothelium with a rotating probe device.

Abstract

A simple in vitro method has been developed to measure the adherence of individual platelets (rather than platelet aggregates) to a collagen-coated glass surface or to the subendothelium of the aorta of rabbits. Platelets are isolated, washed, labeled with /sup 51/Cr, and resuspended in media containing 4% albumin, 40% red blood cells, apyrase, and approximately physiological concentrations of calcium and magnesium. The surfaces are mounted in the form of cylinders on probes, rotated for 10 min at 200 rpm at 37/sup 0/C in a suspension of washed platelets containing 40% red blood cells, and rinsed in EDTA to remove platelet aggregates; the radioactivity associated with the surfaces is measured. Fewer platelets adhered when the suspending fluid contained 4% albumin than when it contained 0.35% albumin. Red blood cells increased platelet adherence. Chelation of divalent cations in the platelet-suspending medium strongly inhibited platelet adherence (approximately 80% inhibition of adherence to collagen and 85% to 95% inhibition of adherence to the subendothelium). These observations raise serious questions concerning the relevance to the physiological situation of studies of platelet adherence in systems in which divalent cations have been chelated. In the present study similar results were obtained with the subendothelium of the aortamore » and a collagen-coated glass surface. With this method, platelet adherence to a collagen-coated surface can be used as a rapid screening method to study the effect of drugs and conditions that may inhibit platelet adherence to the subendothelium.« less