THE ROLE OF EPIDERMAL GROWTH-FACTOR IN PLATELET-ENDOTHELIUM INTERACTIONS

The objective of this study was to determine whether endogenous EGF re leased after submaximal physical exercise, affects platelet - endothel ium interactions, Sixteen healthy male volunteers, aged 23-26 years, w ere submitted to a submaximal bicycle ergometry test. Blood for determ ination of EGF concentrations, platelet function studies (concentratio ns of beta-TG, PF4 and TXB2) acid endothelium activity (LTC, and endot helin-1,2 concentrations) was taken via an intravenous catheter before starting exercise and 15, 30 and 60 min after. A similar scheme was f ollowed to investigate changes in the same parameters induced by a slo w intravenous infusion of 0.3 mg/kg b.w. phentolamine tan a-adrenergic blocker) before exercise. Plasma concentrations of EGF and the marker s of platelet function - beta-TC and PF4 as well as LTC, concentration s increased only 15 min following exercise. The concentrations of TXB2 and endothelium-1,2 were almost unchanged 15 min after the submaximal bicycle ergometry test. Phentolamine markedly decreased the EGF conce ntrations in plasma (15 min following: exercise) while at 30 and 60 mi n after exercise it had no effect on this parameter. No significant ch anges in concentrations of beta-TC, PF4, LTC, and endothelin-1,2 after phentolamine infusion were found. These results show that increase of plasma EGF following exercise was accompanied with increase of beta-T G, PF4 and LTC, concentrations. Inhibition of alpha-adrenergic recepto rs with phentolamine abolished the exercise - induced increase in plas ma EGF concentration. The findings suggest that endogenous EGF may aff ect the platelet function and changes the reactivity of the vascular e ndothelium.