Neurotensin stimulates Cl- secretion in human colonic mucosa in vitro: Role of adenosine

Abstract

Background and Aims: Previous studies indicated that the peptide neurotensin (NT) stimulates Cl- secretion in animal small intestinal mucosa in vitro. In this study, we investigated whether NT causes Cl- secretion in human colonic mucosa and examined the mechanism of this response. Methods: Human mucosal preparations mounted in Ussing chambers were exposed to NT. Drugs for pharmacologic characterization of NT-induced responses were applied 30 minutes before NT. Results: Serosal, but not luminal, administration of NT (10-8 to 10-6 mol/L) induced a rapid, monophasic, concentration- and chloride-dependent, bumetanide-sensitive short-circuit current (Isc) increase that was inhibited by the specific nonpeptide NT receptor antagonists SR 48692 and SR 142948A, the neuronal blocker tetrodotoxin, and the prostaglandin synthesis inhibitor indomethacin. The mast cell stabilizer Iodoxamide and the histamine 1 and 2 receptor antagonists pyrilamine and ranitidine, respectively, did not significantly alter NT-induced Isc increase. In contrast, the adenosine receptor 1 and 2 antagonists inhibited this secretory response, whereas the adenosine uptake inhibitors S-(4-nitrobenzyl)-6-thioguanosine and S-(4-nitrobenzyl)-6-thioinosine and the adenosine deaminase inhibitor deoxycoformycin potentiated NT-induced Isc increase. Serosal adenosine induced a rapid, monophasic, concentration- and chloride-dependent, bumetanide-sensitive Isc increase. Conclusions: NT stimulates chloride secretion in human colon by a pathway(s) involving mucosal nerves, adenosine, and prostaglandins.