Substance P as a mediator of colonic secretory reflexes

The role of substance P in mucosal stroking responses and intrinsic secretory reflexes was analyzed in muscle-stripped segments of distal colon isolated from male albino guinea pigs. Administration of antagonist GR-82334 in muscle-stripped segments of guinea pig distal colon reduced mucosal stroking by 69-75%. The application of neurokinin1 (NK1)- and NK3-receptor agonist caused tetrodotoxin-sensitive increase in short-circuit current indicating the role of substance P together with NK1 and NK3 receptors in mediating secretion.