Platelet Activation During Treadmill Exercise In Patients With Chronic Peripheral Arterial Disease

Abstract

β-Thromboglobulin (β-TG) and platelet factor 4 (PF-4) are specific platelet proteins released during in vivo platelet activation. An increase in PF-4 after exercise- induced myocardial ischemia was reported by Green, L.H. et al.. This observation prompted us to measure β-TG and PF-4 in patients with chronic occlusive arterial disease of the lower limbs and to look for increments during treadmill exercise. β-TG was measured using the Amersham test kit and PF-4 using the radioimmunoassay kit of Abbott Diagnostics Division. Plasma levels in 28 normal individuals ranged for β-TG from 7 to 39 ng/ml with a mean value of 21.0 ng/ml, for PF-4 from 1 to 19 ng/ml with a mean value of 6.0 ng/ml. β-TG and PF-4 were measured in 59 patients with chronic peripheral arterial disease before and 5 min. after treadmill exercising till occurrence of claudication. Plasma levels of β-TG before treadmill exercising ranged from 24 to 260 ng/ml with a mean of 77.9 ng/ml, PF-4 levels ranged from 2 to 240 ng/ml with a mean of 30.4 ng/ml. These levels were significantly higher than those measured in normal individuals.After treadmill exercise β-TG levels showed a statistically significant increase to a mean value of 87.3 ng/ml but PF-4 did not rise significantly (mean value : 32.4 ng/ml). The supplementary increase of already elevated β-TG levels may be explained by enhanced in vivo platelet activation during treadmill exercising till occurrence of claudication. As the clearance of PF-4 from human plasma has been shown to be much faster than the clearance of β-TG increases in PF-4 levels may be more difficult to detect during dynamic explorations of the vascular system.