COLLAGEN-INDUCED THROMBUS FORMATION IN FLOWING NONANTICOAGULATED HUMAN BLOOD FROM HABITUAL SMOKERS AND NONSMOKING PATIENTS WITH SEVERE PERIPHERAL ATHEROSCLEROTIC DISEASE

The objective of the present study was to investigate collagen-induced platelet thrombus formation at arterial blood flow conditions in nona nticoagulated blood from habitual smokers and from nonsmoking patients with severe peripheral atherosclerotic disease. Collagen-induced thro mbogenesis was elicited in native blood drawn directly from an antecub ital vein over immobilized type III collagen fibrils coated on a cover slip positioned in a parallel-plate perfusion chamber. The wall shear rates at the collagen surface were comparable to those encountered in medium-sized (650 s(-1)) and moderately stenosed (2600 s(-1)) arteries . Thrombus formation in blood from habitual smokers after 10 hours of smoking abstinence appeared to be not different from thrombus formatio n in blood from healthy nonsmokers. However, immediately after a cigar ette had been smoked, thrombus volume in blood from the same individua ls was increased twofold at the highest shear rate (P<.05). Thus, the thrombotic response was temporarily upregulated after smoking. Thrombu s formation in blood from nonsmoking patients with severe peripheral a therosclerotic disease was neither enhanced nor decreased but was with in the range of the nonsmoking control subjects. However, fibrinopepti de A generation after 4 minutes of perfusion at 2600 s(-1) was higher in blood from the atherosclerotic patients (P<.05) and associated with a higher plasma fibrinogen level (P<.005). Thus, signs of changed pla telet reactivity in flowing nonanticoagulated blood were encountered o nly in the habitual smokers immediately after they had smoked a cigare tte.