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Methylmercury and the skeletal muscle receptor
The Journal of Pharmacy and Pharmacology
|July 1, 1976
Summary
Methylmercury inhibits neuromuscular transmission by affecting muscle contractions, even when nerve signals are present. This neurotoxin
Area of Science:
- Neuroscience
- Toxicology
- Pharmacology
Background:
- Methylmercury is a potent neurotoxin.
- Neuromuscular transmission relies on acetylcholine binding to cholinergic receptors.
Purpose of the Study:
- To investigate the effects of methylmercury on neuromuscular function.
- To elucidate the mechanism of methylmercury's inhibitory action.
Main Methods:
- Isolated rat phrenic-nerve hemidiaphragm preparation.
- Frog rectus abdominis muscle bioassay.
- Electrophysiological recordings and dose-response curves.
Main Results:
- Methylmercury (2 X 10(-5) M) inhibited muscle contractions in the rat hemidiaphragm.
- Nerve action potentials and direct muscle stimulation remained intact.
- Methylmercury shifted acetylcholine dose-response curves rightward and reduced maximal response in frog rectus muscles.
- Inhibition was not reversed by L-cysteine or D-penicillamine but partially prevented by (+)-tubocurarine.
Conclusions:
- Methylmercury impairs neuromuscular transmission.
- The mechanism involves interference with cholinergic receptors, potentially by acting on disulfide bonds.
- This action is distinct from effects on nerve conduction or direct muscle excitability.