Binding of Endothelin-1 To Human Blood Monocyte

Abstract

Monocyte attachment to the endothelium and migration into the vessel intima are the initiating steps in atherogenesis. This is thought to be facilitated by endothelin-1 (ET-1) as a potent chemoattractant to human blood monocytes. To explore the presence of ET-1 receptor(s) on the monocyte, we studied the binding of ET-1 to freshly isolated human blood monocytes, in the laboratory of the Institute of Clinical Biochemistry, University of Bon, Germany in 1995. Radioligand binding studies revealed the presence of two distinct subclasses of binding sites with apparent dissociation constants, K s, of 10.3 pM and 3.5 nM and maximal binding capacities, B s, of 0.027 fmol and 0.63 d max fmol/1.5x105 cells. Using monocyte migration as a response to ET-1, and ET-1 receptor antagonists BQ-123, BQ- 18257B and IRL-1038, the presence of two ET receptor subtypes, ET and ET , were detected. These results suggest A B that the chemotactic stimulus introduced by ET-1 can be activated ET-1 specific receptors on the monocytes.

Keywords

• Endothelin-1
• monocyte
• receptor-binding