Abstract
Ganglionic firing produced by 4-(m-chlorophenylcarbamoyloxy)-2-butynyltrimethylammonium chloride (McN-A-343) in the cat superior cervical ganghion had two components: a late-occurring response that was prevented by atropine and an early-occurring response that was resistant to blockade by either hexamethonium (C6) or atropine. The discharge was accompanied by a sustained depolarization. Whereas small doses of McN-A-343 enhanced transmission, large doses caused ganglionic blockade. Atropine had no effect on the blocking actions of McN-A-343. Although the blockade by McN-A-343 was antagonized by tetanic pregangiionic stimulation, the block was not frequency-dependent. Ganglionic firing by KCl, acetylcholine or tetramethylammonium was enhanced at a time when transmission was blocked. Furtrethonium and its 5-methyl derivative have ganglionic actions identical to those of McN-A-343. It was concluded that these compounds stimulate two distinctive types of ganglionic receptors and cause a blockade of transmission by a mechanism different from that of C6.
Footnotes
- Received January 23, 1967.
- Accepted March 3, 1967.
- © 1967 by The Williams & Wilkins Company
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