[Studies on the muscarine receptors in XXXX gastric smooth muscle].

@entity73345 @entity1022 @entity4140 @entity4138 @entity35
It has been reported that the two types of muscarinic receptors, "M1" and "M2", exist in the opossum lower esophageal sphincter. The presence of these muscarinic receptor subtypes had been confirmed with the discovery of the M1 selective antagonist, @entity4140 . But little is known about muscarinic receptor subtypes in gastric smooth muscle. The aim of this study was to identify the muscarinic receptor subtypes on the gastric smooth muscle responsible for the contraction of @entity35 gastric muscle strip. Also, we examined the mechanism of the action of @entity73345 on @entity35 gastric smooth muscle in vitro. The stimulation of M2 receptor caused the contraction of the gastric smooth muscle. @entity4138 , selective M1 agonist, caused weak contraction of the gastric smooth muscle, and this response was not affected by the selective M1 antagonist, @entity4140 . @entity73345 stimulated M2 receptor and caused the gastric smooth muscle contraction. We conclude that the contraction of the gastric smooth muscle is caused by the stimulation of the M2 receptor and this reaction was not affected by @entity1022 , suggesting the M2 receptor is located directly on the gastric smooth muscle. The weak contraction of the gastric smooth muscle caused by @entity4138 was not affected by the selective M1 antagonist, @entity4140 , suggesting that @entity4138 may not be a pure M1 selective agonist. The action of @entity73345 is supposed to stimulate the M2 receptor.
