ENDOTHELIN DOES NOT AFFECT AGGREGATION OF HUMAN PLATELETS

Summary. Endothelin (ET‐1) is a recently discovered endothelial‐derived peptide with pronounced vasoconstrictor activity. The present study addressed whether ET‐1, in analogy with several other vasoactive agents, can induce or modulate aggregation of human platelets in vitro. Venous blood from healthy donors was collected in citrate or heparin and platelet‐rich plasma (PRP) was prepared. Portions of the PRP were added to drugs, and platelet aggregation was recorded according to Born & Cross (1963). ET‐1 added to the PRP (final concentrations 1–100 nM) did not induce aggregation of platelets, either in citrate‐ or heparin‐containing plasma. Adenosine‐diphosphate (0·5‐2 μM) or thrombin (0·1‐0·4 NIH units ml‐1) induced dose‐dependent aggregation of platelets in citrate‐ or heparin‐containing PRP; such aggregation was, however, not affected by ET‐1 (1–100 μM) either. We conclude that ET‐1, in contrast to other endothelial‐derived vasoactive agents, lacks direct effect on platelet aggregation in vitro. Copyright © 1990, Wiley Blackwell. All rights reserved