Different substance P receptors are found on mucosal epithelial cells and submucous neurons of the guinea-pig small intestine

Abstract

The action of substance P (SP) on mucosal ion transport has been investigated in the guinea-pig small intestine. Segments of intestine were dissected free of external muscle and myenteric plexus and mounted in Ussing chambers. Short-circuit current (Isc) was measured as an indication of net ion transport across the tissue. SP (>10-10 M) added to the submucosal side of the tissue caused a transient increase in Isc. Tetrodotoxin (TTX, 10-7 M) decreased the maximum SP response to 11% of the control value. TTX completely inhibited the response to electrical field stimulation but had no effect on Isc increases due to carbachol or theophylline. In the presence of hyoscine (10-7 M) the SP response ..