Effects of various peptides on isolated rabbit lower esophageal sphincter.
Strips of lower esophageal sphincter (LES) from rabbits were tested for their responses to several peptides, and to electrical field stimulation (EFS) under the presence of some peptides. Substance P (SP), motilin, and bombesin induced contraction, and vasoactive intestinal peptide (VIP) induced relaxation. SP- and bombesin-induced contractions were antagonized by SP antagonist. VIP-induced relaxation was antagonized by phentolamine and VIP antagonist. Pretreatment with atropine, phentolamine, and diphenhydramine antagonized the motilin- and bombesin-induced contraction. Pretreatment with tetrodotoxin (TTX) attenuated the motilin- and bombesin-induced contraction, but not the SP-induced contraction and VIP-induced relaxation. EFS induced contraction, which was attenuated by TTX. Calcitonin gene-related peptide and neuropeptide Y had no effect on LES; however, they attenuated EFS-induced contraction. These findings suggest some characteristic peptidergic involvement in rabbit LES smooth muscle.
Department of Anesthesiology, Kobe University School of Medicine, Japan.
A
A
Kohjitani
J
J
Shirakawa
S
S
Okada
H
H
Obara
D000818:Animals; D001285:Atropine / Q000494:pharmacology; D001839:Bombesin / Q000037:antagonists & inhibitors / Q000494:pharmacology; D015740:Calcitonin Gene-Related Peptide / Q000494:pharmacology; D004155:Diphenhydramine / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004943:Esophagogastric Junction / Q000187:drug effects*; D008297:Male; D009037:Motilin / Q000037:antagonists & inhibitors / Q000494:pharmacology; D009119:Muscle Contraction / Q000187:drug effects; D009126:Muscle Relaxation / Q000187:drug effects; D009130:Muscle, Smooth / Q000187:drug effects*; D009478:Neuropeptide Y / Q000494:pharmacology; D010455:Peptides / Q000494:pharmacology*; D010646:Phentolamine / Q000494:pharmacology; D011433:Propranolol / Q000494:pharmacology; D011817:Rabbits; D013373:Substance P / Q000494:pharmacology; D014660:Vasoactive Intestinal Peptide / Q000037:antagonists & inhibitors / Q000494:pharmacology
D009478:Neuropeptide Y; D010455:Peptides; D013373:Substance P; D014660:Vasoactive Intestinal Peptide; D009037:Motilin; D001285:Atropine; D004155:Diphenhydramine; D011433:Propranolol; D015740:Calcitonin Gene-Related Peptide; D001839:Bombesin; D010646:Phentolamine