Functional evidence linking potassium channels and afferent nerve-mediated mucosal protection in rat stomach.
Adenosine triphosphate-dependent potassium (K+ATP) channels in several types of vascular smooth muscles mediate the vasodilation induced by calcitonin gene-related peptide (CGRP). Upon stimulation, primary afferent nerve terminals in the gastric mucosa release CGRP which mediates a protective hyperemia. We tested the hypothesis that a potassium channel blocker aggravates gastric mucosal injury by impairing afferent nerve-mediated hyperemia in the gastric mucosa. Rats were treated with K+ATP channel blocker, glybenclamide (20 mg/kg intravenously). Intragastric added ethanol (0.15 N HCl, 15% ethanol) and intragastric capsaicin (160 microM) were also administered. Glybenclamide aggravated the acidified ethanol-induced mucosal injury, and attenuated the mucosal hyperemia (hydrogen gas clearance) induced by intragastric acidified ethanol and intragastric capsaicin. These findings suggest for the first time that K+ATP channels modulate primary afferent nerve-mediated mucosal defense mechanisms in the gastric mucosa.
Iwata
F
F
First Department of Internal Medicine, Nagoya City University School of Medicine, Nagoya, Japan.
Koo
A
A
Itoh
M
M
Lam
K
K
Leung
J W
JW
Leung
F W
FW
D000818:Animals; D002211:Capsaicin / Q000008:administration & dosage; D000431:Ethanol / Q000008:administration & dosage; D005744:Gastric Acid; D005753:Gastric Mucosa / Q000187:drug effects / Q000294:innervation / Q000502:physiology*; D005905:Glyburide / Q000494:pharmacology; D006940:Hyperemia / Q000139:chemically induced; D008297:Male; D009475:Neurons, Afferent / Q000502:physiology*; D015221:Potassium Channels / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley
D015221:Potassium Channels; D000431:Ethanol; D002211:Capsaicin; D005905:Glyburide