Calcitonin gene-related peptide affords gastric mucosal protection by activating potassium channel in Wistar rat.
OBJECTIVE
Calcitonin gene-related peptide (CGRP) protects the gastric mucosa against injurious stimuli in various experimental models. The underlying mechanism could be the increase in gastric mucosal blood flow (GMBF). A number of endogenous vasodilators exert their effects through the activation of adenosine triphosphate (ATP)-sensitive potassium (KATP) channels on vascular smooth muscle. The present experiments were performed to elucidate whether CGRP increases GMBF through the activation of KATP channels and whether the channels are involved in the protection by CGRP of gastric mucosa.


METHODS
GMBF was determined by the hydrogen-clearance technique in male Wistar rats. Mucosal lesions were produced by intragastric superfusion with 0.15N HCland 15% ethanol for 40 minutes. Effects of an agonist (Y-26763, intra-arterially) and an inhibitor (glibenclamide, intravenously) of KATP channels were tested.


RESULTS
Y-26763 increased GMBF, which was abolished by glibenclamide, and a CGRP-induced increase in GMBF was attenuated by glibenclamide. Macroscopic and microscopic lesions were exacerbated by human CGRP-(8-37) (a CGRP-1 receptor antagonist; intra-arterially) and glibenclamide but were ameliorated by exogenous CGRP (intra-arterially).


CONCLUSIONS
CGRP protects the gastric mucosa against ulcerogenic stimuli, at least in part, through the activation of KATP channels in rats.
Doi
K
K
Second Department of Internal Medicine, Faculty of Medicine, Kyushu University, Fukuoka, Japan.
Nagao
T
T
Kawakubo
K
K
Ibayashi
S
S
Aoyagi
K
K
Yano
Y
Y
Yamamoto
C
C
Kanamoto
K
K
Iida
M
M
Sadoshima
S
S
Fujishima
M
M
D000818:Animals; D001578:Benzopyrans / Q000494:pharmacology; D015740:Calcitonin Gene-Related Peptide / Q000502:physiology*; D005753:Gastric Mucosa / Q000502:physiology*; D005905:Glyburide / Q000494:pharmacology; D006801:Humans; D015640:Ion Channel Gating; D008297:Male; D026902:Potassium Channel Blockers; D015221:Potassium Channels / Q000819:agonists / Q000502:physiology*; D051381:Rats; D017208:Rats, Wistar
D001578:Benzopyrans; D026902:Potassium Channel Blockers; D015221:Potassium Channels; D015740:Calcitonin Gene-Related Peptide; C074338:Y 26763; D005905:Glyburide