title: Platelet affinity for burro aorta collagen.
abstract: Despite ingenious concepts, there are no unequivocal clues as to what, when, and how some undefined biochemical factor(s) or constituent(s) that localizes in the arterial wall can precipitate a thromboatheromatous lesion or arterial disease. The present study focused on the extraction, partial purification, and characterization of a collagen-active platelet stimulator from the aortas of aged burros. The aggregator moiety in the aorta extracts invariably had a higher affinity for platelets in citrated platelet-rich plasma of human beings than for platelets of homologous burros. The platelet-aggregating factor(s) in the aorta extract was retained by incubation with alpha-chymotrypsin. Platelet-aggregating activity was rapidldy abolished after incubation with collagenase, as determined by plateletaggregometry tests. Evidence based on light microscope and polysaccharide histochemical reactions indicates a probability that the intracellular amorphous matrix (PAS-positive) and filamentous components (PTAH-positive) expelled from smooth muscle cells disrupted during homogenization of the aorta may be a principle source of a precursor collagen species which is a potent inducer of platelet aggregation.
mesh_terms: D000818:Animals; D001013:Aorta, Thoracic / Q000032:analysis* / Q000033:anatomy & histology; D002918:Chymotrypsin / Q000378:metabolism; D003094:Collagen / Q000302:isolation & purification / Q000494:pharmacology*; D006736:Horses; D006801:Humans; D003012:Microbial Collagenase / Q000378:metabolism; D010527:Perissodactyla / Q000378:metabolism*; D010974:Platelet Aggregation / Q000187:drug effects*
chemical_list: D003094:Collagen; D002918:Chymotrypsin; D003012:Microbial Collagenase