HCl-activated neural and epithelial vanilloid receptors (TRPV1) in cat esophageal mucosa.
To test whether transient receptor potential channel vanilloid subfamily member-1 (TRPV1) mediates acid-induced inflammation in the esophagus, a tubular segment of esophageal mucosa was tied at both ends, forming a sac. The sac was filled with 0.01 N HCl (or Krebs buffer for control) and kept in oxygenated Krebs buffer at 37 degrees C. The medium around the sac (supernatant) was collected after 3 h. Supernatant of the HCl-filled sac abolished contraction of esophageal circular muscle strips in response to electric field stimulation. Contraction was similarly abolished by supernatant of mucosal sac filled with the TRPV1 agonist capsaicin (10(-6) M). These effects were reversed by the selective TRPV1 antagonist 5'-iodoresiniferatoxin (IRTX) and by the platelet-activating factor (PAF) receptor antagonist CV9388. Substance P and CGRP levels in mucosa and in supernatant increased in response to HCl, and these increases were abolished by IRTX and by tetrodotoxin (TTX) but not affected by CV9388, indicating that substance P and CGRP are neurally released and PAF independent. In contrast, the increase in PAF was blocked by IRTX but not by TTX. Presence of TRPV1 receptor was confirmed by RT-PCR and by Western blot analysis in whole mucosa and in esophageal epithelial cells enzymatically isolated and sorted by flow cytometry or immunoprecipitated with cytokeratin antibodies. In epithelial cells PAF increased in response to HCl, and the increase was abolished by IRTX. We conclude that HCl-induced activation of TRPV1 receptors in esophageal mucosa causes release of substance P and CGRP from neurons and release of PAF from epithelial cells.
Cheng
Ling
L
Department of Medicine, Rhode Island Hospital and Brown University, Providence, Rhode Island, USA.
de la Monte
Suzanne
S
Ma
Jie
J
Hong
Jie
J
Tong
Ming
M
Cao
Weibiao
W
Behar
Jose
J
Biancani
Piero
P
Harnett
Karen M
KM
D000818:Animals; D015740:Calcitonin Gene-Related Peptide / Q000378:metabolism; D002211:Capsaicin / Q000494:pharmacology; D002415:Cats; D004224:Diterpenes / Q000494:pharmacology; D004558:Electric Stimulation; D004847:Epithelial Cells / Q000187:drug effects / Q000378:metabolism*; D004947:Esophagus / Q000187:drug effects / Q000294:innervation / Q000378:metabolism*; D006851:Hydrochloric Acid / Q000378:metabolism*; D066298:In Vitro Techniques; D008297:Male; D009092:Mucous Membrane / Q000187:drug effects / Q000294:innervation / Q000378:metabolism*; D009119:Muscle Contraction / Q000187:drug effects; D010972:Platelet Activating Factor / Q000378:metabolism; D010980:Platelet Membrane Glycoproteins / Q000378:metabolism; D043562:Receptors, G-Protein-Coupled / Q000378:metabolism; D013268:Stimulation, Chemical; D013368:Submucous Plexus / Q000187:drug effects / Q000378:metabolism*; D013373:Substance P / Q000378:metabolism; D050916:TRPV Cation Channels / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D013779:Tetrodotoxin / Q000494:pharmacology
D004224:Diterpenes; D010972:Platelet Activating Factor; D010980:Platelet Membrane Glycoproteins; D043562:Receptors, G-Protein-Coupled; D050916:TRPV Cation Channels; C468130:iodoresiniferatoxin; C039351:platelet activating factor receptor; D013373:Substance P; D013779:Tetrodotoxin; D015740:Calcitonin Gene-Related Peptide; D006851:Hydrochloric Acid; D002211:Capsaicin