Endothelin-1 induces mucosal mast cell degranulation and tissue injury via ETA receptors.

The effects of endothelin-1 (ET-1) on mucosal mast cells are of special interest, since they may be an important component of the tissue response that occurs during ischaemic preconditioning or ischaemia/re-oxygenation injuries. Increasing doses of ET-1 were administered intravenously to anaesthetized rats. In a second series of experiments, animals were pretreated with the ET(A) receptor antagonists BQ-610 or ETR-P1/fl peptide, or with the ET(B) receptor antagonist IRL-1038. Intestinal perfusion changes were recorded, and the proportion of degranulated mast cells and the degree of mucosal damage were determined in ileal biopsies. ET-1 induced dose-dependent alterations in the haemodynamic and morphological parameters, and caused significant mast cell degranulation. These changes were inhibited significantly by pretreatment with the ET(A) receptor antagonists, but not with the ET(B) receptor antagonist. We conclude that a cross-talk exists between endothelial cell-derived humoral mediators and the intestinal mast cell system.