Possible mechanisms related to contraction of the bovine iris sphincter in the presence of acetylcholine and carbachol

✍ Scribed by Ryo Suzuki; Shunsaku Kobayashi

• Book ID: 104647468
• Publisher: Springer-Verlag
• Year: 1988
• Tongue: English
• Weight: 408 KB
• Volume: 70
• Category: Article
• ISSN: 0012-4486
• DOI: 10.1007/bf00157059

✦ Synopsis

Using tension-recording methods, we compared the effects of acetylcholine (Ach) and carbachol on the bovine iris sphincter. The isolated muscle strips were mounted in a 0.2 ml organ bath, through which Krebs solution at 36 ~ flowed continuously. There was a tenthousandfold difference in potency between carbachol and Ach in this tissue. Neostigmine or eserine, acetylcholinesterase (AchE) inhibitors, produced a larger contraction of the muscle than did Ach. Ach-induced contractions were potentiated by low doses of anti-AchEs and were inhibited by atropine.

This in vitro study suggests that Ach and/or endogenous chemical agents may be spontaneously released from tissues and that AchE activities in this tissue strongly inhibit or mask the Ach action, probably in order to protect the nerve terminals from released Ach.