Leucomyosuppressin, isolated from head extracts of the cockroach Leucophaea maderae, inhibits evoked transmitter release at the mealworm neuromuscularjunction.
Brevetoxin B is a polyketide neurotoxin produced by Karenia species and other dinoflagellates. It binds to site 5 on the alpha subunit of voltage-gated sodium channels (IC50 = 15 nM) on neurons at the neuromuscularjunction, causing the channel to open irreversibly at potentials more negative than normal, discharging action potentials repetitively. Brevetoxin B is ichthyotoxic at nanomolar concentrations and is responsible for an illness described as neurotoxic shellfish poisoning.
Ambenonium chloride tetrahydrate is a salt of ambenonium --- a quaternary ammonium compound with parasympathomimetic activity. It is a cholinesterase inhibitor used in the management of myasthenia gravis. Myasthenia gravis occurs when the body produces antibodies against acetylcholine receptors, and thus inhibits signal transmission across the myoneural junction. Ambenonium chloride is a rapid indirect-acting cholinergic agonist that reversibly blocks the activity of acetylcholinesterase, thereby prevents acetylcholine hydrolysis and prolonging its activity on nicotinic receptors at the neuromuscularjunction.