1989 Volume 36 Issue 1 Pages 23-28
We measured the intra-platelet content of human epidermal growth factor (hEGF) and beta-thromboglobulin (β-TG) and the quantities of these released from platelets during in vitro aggregation. The intra-platelet amounts of hEGF and β-TG in 108 platelets were 104.9±18.9 (Mean±SEM) pg and 2920.9±149.9 ng, respectively. During platelet aggregation elicited by 9, 11-epithio-11, 12-methano-thromboxane A2, a stable thromboxane A2 agonist, hEGF and β-TG were released in amounts about 50% and 40% of the respective content in platelets. Also during arachidonate-induced aggregation, hEGF and β-TG were released at about 60% and 50%, respectively. Various concentrations of thromboxane A2 antagonist, (9, 11), (11, 12)-di-deoxa-9, 11-dimethyl-methano-11, 12-methano-13, 14-dihydro-13-aza-14-oxo-l5-cyclopentyl-16, 17, 18, 19, 20-pentanor-15-epi-thromboxane A2, suppressed both aggregation and release reactions in a dose-dependent manner. There were good correlations between the platelet aggregation rate and released β-TG (r=0.9368, p<0.01) or hEGF (r=0.8931, p<0.01) and between released β-TG and hEGF (r=0.9385, p<0.01). These results suggest that hEGF is released from platelets in a similar fashion to β-TG in vitro.
