Ba2+ selectively inhibits receptor-mediated contraction of the esophageal muscularis mucosae.
The aim of the present study was to examine the effect of Ba2+ on acetylcholine- and KCl-induced contractions of the guinea-pig esophageal muscularis mucosae. When the muscularis mucosae was pretreated with nicardipine (1 microM), Ba2+ (0.1-30 mM) markedly inhibited the acetylcholine (3 microM)-induced tone, and at 10-30 mM the tone returned to its basal level. In contrast, Ba2+ (0.1-30 mM) slightly increased the KCl (60 mM)-induced tone. Moreover, the Ba2+ (30 mM)-increased KCl tone was completely inhibited by treatment with nicardipine (0.3-1 microM). In conclusion, Ba2+ both selectively inhibits receptor-mediated contraction of the muscularis mucosae and itself permeates through voltage-dependent Ca2+ channels.
Uchida
K
K
Department of Pharmacology, Dokkyo University School of Medicine, Mibu, Tochigi, Japan.
Yuzuki
R
R
Kamikawa
Y
Y
D000109:Acetylcholine / Q000494:pharmacology; D000818:Animals; D001464:Barium / Q000494:pharmacology*; D017609:Barium Compounds / Q000494:pharmacology; D015220:Calcium Channels / Q000502:physiology; D002712:Chlorides / Q000494:pharmacology; D018680:Cholinergic Antagonists / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D004947:Esophagus / Q000187:drug effects*; D006168:Guinea Pigs; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects*; D009529:Nicardipine / Q000494:pharmacology; D011189:Potassium Chloride / Q000494:pharmacology*; D014665:Vasodilator Agents / Q000494:pharmacology
D017609:Barium Compounds; D015220:Calcium Channels; D002712:Chlorides; D018680:Cholinergic Antagonists; D014665:Vasodilator Agents; C024986:barium chloride; D001464:Barium; D011189:Potassium Chloride; D009529:Nicardipine; D000109:Acetylcholine