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Selective effects of an octopus toxin on action potentials
Author(s) -
Dulhunty Angela,
Gage Peter W.
Publication year - 1971
Publication title -
the journal of physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.802
H-Index - 240
eISSN - 1469-7793
pISSN - 0022-3751
DOI - 10.1113/jphysiol.1971.sp009626
Subject(s) - octopus (software) , neuromuscular transmission , toxin , chemistry , biophysics , extracellular , neuromuscular junction , sartorius muscle , membrane potential , sodium , sodium channel , pharmacology , biochemistry , endocrinology , biology , neuroscience , computational chemistry , organic chemistry
1. A lethal, water soluble toxin (Maculotoxin, MTX) with a molecular weight less than 540, can be extracted from the salivary glands of an octopus ( Hapalochlaena maculosa ). 2. MTX blocks action potentials in sartorius muscle fibres of toads without affecting the membrane potential. Delayed rectification is not inhibited by the toxin. 3. At low concentrations (10 −6 ‐10 −5 g/ml.) MTX blocks action potentials only after a certain number have been elicited. The number of action potentials, which can be defined accurately, depends on the concentration of MTX and the concentration of sodium ions in the extracellular solution. 4. The toxin has no post‐synaptic effect at the neuromuscular junction and it is concluded that it blocks neuromuscular transmission by inhibiting action potentials in motor nerve terminals.