The gut neuropeptide, neuromedin U octapeptide (NMU-8) produced transient elevations in short-circuit current (EC50 = 0.7 nmol/1) after its contraluminal administration to sheets of porcine distal jejunal mucosa in vitro. Mucosal responses to NMU-8 were unaffected by 1 μmol/1 atropine or hexamethonium, but were abolished by tetrodotoxin (0.1 μmol/l), dependent upon extracellular Cl, and underwent tachyphylaxis upon repeated peptide application. NMU-8 did not affect contractility of isolated jejunal longitudinal muscle. Thus, NMU-8 appears to selectively modify intestinal ion transport through interactions with non-cholinergic enteric neurons.
Bibliographical noteFunding Information:
The authors thank Ward A. Ortman for excellent technical assistance in performing smooth muscle bioassays. This work was funded in part by Minnesota Agricultural Experiment Station Grant MN-061-37 and National Institutes of Health Grant DK-37497.
- (Longitudinal muscle, Contractility, Pig)
- Enteric nervous system
- Intestinal ion transport
- Jejunum (distal)
- Neuromedin U