Isotonic contractions were recorded from the filarial nematode, Dipetalonema viteae (Acanthocheilonema viteae), in an isolated tissue chamber.
Nicotine (10−6 m) and pilocarpine (10−5 m) increased the spontaneous contractions in the intact filariid, but acetylcholine (ACh, 10−4 m) and muscarine (10−5 m) were inactive.
When ACh was applied to an opened D. viteae, it was 10,000 times more potent. This indicates that the cuticle is an effective barrier to the penetration of ACh to the muscle cells.
The effects of ACh on the opened D. viteae were not affected by hexamethonium (10−3 m) or atropine (10−5 m) and were only partially reduced by (+)‐tubocurarine (10−4 m).
γ‐Aminobutyric acid (GABA, 10−3 m) reduced the spontaneous activity of the intact D. viteae; however, the effect of GABA had a slow onset and recovery. Muscimol (10−5 m) was more potent than GABA and had a more rapid onset and recovery.
GABA was 1,000 times more potent on the opened D. viteae than on the intact D. viteae. Baclofen (10−3 m) was inactive on both preparations.
The effect of GABA was not antagonized by bicuculline (10−4 m), picrotoxin (10−5 m) or penicillin G (10−3 m).
It is concluded that the filariid cuticle acts like a lipid structure and blocks the penetration of polar substances, such as ACh and GABA. Also, due to the lack of efficacy of the ACh and GABA antagonists, it was concluded that the nematode receptors are somewhat different from the mammalian ACh and GABA receptors.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.