Evidence that stretch receptors for peristalsis are located in the mucosal layer of the guinea pig ileum.

Location of stretch receptors triggering the peristalsis was investigated in the isolated guinea pig ileum. Peristalsis was cyclically induced by perfusing the lumen with Krebs solution flowing at a constant rate. Peristalsis was promptly abolished by serosally applied 3 x 10(-7) M tetrodotoxin, 10(-4) M lidocaine, 10(-6) M morphine or 10(-5) M nicotine, confirming the claim that peristalsis was neurally regulated by the myenteric plexus. Intraluminal application of 3 x 10(-7) M tetrodotoxin not only blocked the peristalsis, but also inhibited the contractions of the longitudinal muscle elicited by transmural stimulation or 10(-4) M nicotine by the same extent as those by serosal tetrodotoxin, suggesting that the blockade of peristalsis was due to the tetrodotoxin infiltrating into the muscle layer. In contrast, intraluminal application of 0.1% glutaraldehyde or perfusing the lumen with the low NaCl (20 mM)-containing Krebs solution abolished the peristalsis without critically inhibiting the neurogenic contractions of the longitudinal muscle, indicating that the blockade of peristalsis by these intraluminal treatments was ascribed to the actions on the mucosal layer. These results may imply that stretch receptors are located in the mucosal layer of the guinea pig ileum, and the impairment of the functions of these receptors by the intraluminal treatments leads to the blockade of the peristalsis.