Autocrine effects of endothelin-1 on leukocyte-endothelial interaction: stimulation of endothelin B receptor subtype reduces endothelial adhesiveness via a nitric oxide-dependent mechanism.
The effects of endothelin-1 (ET-1) on P-selectin-mediated leukocyte endothelial interaction were examined in vitro. Adherence of autologous polymorphonuclear leukocytes (PMNs) to the endothelium was markedly enhanced by endothelial stimulation with either (2 U/mL) thrombin, (1 mumol/L) histamine, or (100 nmol/L) phorbol myristate acetate (PMA). In contrast, ET-1 alone (10 and 100 nmol/L) only slightly increased the number of adhering PMNs. The increased PMN adherence to thrombin- or histamine-stimulated endothelium, which was blocked by an anti-P-selectin monoclonal antibody, was also significantly attenuated by preincubation of coronary segments with (100 nmol/L) ET-1. We further investigated the mechanism of this anti-adherence action of ET-1 on thrombin-stimulated endothelial adhesiveness. Preincubation of coronary segments with a selective ETA receptor antagonist, BQ485 (1 mumol/L), had no effect on ET-1 inhibition of thrombin-induced PMN adherence. In contrast, preincubation with a selective ETB receptor antagonist, BQ788 (1 mumol/L) significantly reversed ET-1 inhibition of thrombin-induced PMN adherence, whereas the selective ETB receptor agonist BQ-3020 mimicked the inhibitory action of ET-1 on thrombin-induced PMN adherence. Furthermore, (100 mumol/L) N omega-nitro-L-arginine methyl ester (L-NAME), a nitric oxide synthase (NOS) inhibitor, significantly attenuated ET-1 inhibition of thrombin-stimulated PMN adherence. These results suggest that ET-1 may inhibit P-selectin-mediated leukocyte-endothelial interaction via ETB receptor stimulation and subsequent endothelial NO formation. This autocrine effect of ET-1 may be involved in pathophysiologic states such as early atherogenesis by preventing leukocyte-endothelial interaction in constricted blood vessels.
Department of Physiology, Jefferson Medical College, Thomas Jefferson University, Philadelphia, PA 19107-6799, USA.
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D000818:Animals; D002415:Cats; D002448:Cell Adhesion / Q000502:physiology; D002478:Cells, Cultured; D003331:Coronary Vessels / Q000166:cytology; D019332:Endothelin-1 / Q000494:pharmacology / Q000502:physiology*; D006632:Histamine / Q000494:pharmacology; D009504:Neutrophils / Q000378:metabolism*; D009569:Nitric Oxide / Q000502:physiology*; D019007:P-Selectin / Q000502:physiology; D044023:Receptor, Endothelin B; D017466:Receptors, Endothelin / Q000145:classification / Q000187:drug effects* / Q000502:physiology; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D013917:Thrombin / Q000494:pharmacology
D019332:Endothelin-1; D019007:P-Selectin; D044023:Receptor, Endothelin B; D017466:Receptors, Endothelin; D009569:Nitric Oxide; D006632:Histamine; D013917:Thrombin; D013755:Tetradecanoylphorbol Acetate