Increased vascular permeability by a specific agonist of protease‐activated receptor‐2 in rat hindpaw

The present study examined the effect of intraplantar (i.pl.) administration of a selective agonist of protease‐activated receptor (PAR)‐2, SLIGRL‐NH2(PP6‐NH2), on vascular permeability in rat hindpaw. PP6‐NH2, administered i.pl. at 10–100 nmol per paw, enhanced vascular permeability and caused oedema formation in rat hindpaw. SLIGRL (PP6‐OH) and trypsin, by i.pl. administration, also elicited an increase in vascular permeability, although i.pl. administration of the mixture of constituent amino acids of PP6‐OH at an equivalent dose did not. The PP6‐NH2‐induced increase in vascular permeability was abolished by repeated pretreatment with compound 48/80 to deplete bioactive amines in mast cells. These findings suggest that the activation of PAR‐2 induces acute inflammation, at least partially, via mast cell degranulation in rat hindpaw. British Journal of Pharmacology (1998) 125, 419–422; doi:10.1038/sj.bjp.0702063