PAR-4 Agonist Peptide, amide (PAR-4-AP; AY-NH2) is a proteinase-activated receptor-4 (PAR-4) agonist, which has no effect on either PAR-1 or PAR-2 and whose effects are blocked by a PAR-4 antagonist. IC50 & Target: PAR-4^[1] In Vivo: Compared with their BALB/cBy controls, SCID mice have a significantly greater abdominal response to colorectal distension (CRD) at the distension levels of 0.04 to 0.1 mL increasing the intensity of EMG response by 384% to 132%, respectively (P<0.01; P<0.01; P<0.01; P<0.001). PAR-4 activation effectively reverses this hypersensitivity (P<0.01, P<0.05; P<0.05; P<0.05) ^[1].