Premium
Neuromuscular transmission without sodium activation of the presynaptic nerve terminal in the lobster.
Author(s) -
Kawai N,
Niwa A
Publication year - 1980
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.1980.sp013350
Subject(s) - inhibitory postsynaptic potential , depolarization , tetrodotoxin , neurotransmission , neuromuscular transmission , neuromuscular junction , axon , chemistry , biophysics , synapse , neuroscience , motor nerve , free nerve ending , sodium channel , anatomy , biology , anesthesia , sodium , medicine , biochemistry , receptor , organic chemistry
1. We studed Na‐independent synaptic transmission in the inhibitory synapse of the walking leg of the spiny lobster (Palinurus japonicus). 2. After loading the preparation with tetrodotoxin (TTX), brief depolarizing current injected in the inhibitory axon produced a small action potential, which propagated to the nerve terminal and gave rise to inhibitory post‐synaptic potentials (i.p.s.p.) 3. The presynaptic action potential, in the presence of TTX, failed to propagate after removing Na+ in the solution. The TTX‐resistant action potential was decreased, but not blocked by 30 mM‐CoCl2. 4. When 4‐aminopyridine (4‐AP) was added to low Na+ or Na‐free solution containing TTX synaptic transmission was restored. When the duration of the current pulse was increased, graded i.p.s.p. were evoked. 5. In high Ca2+ solutions containing K blockers, action potentials with prolonged duration were evoked. 6. The action potential of the presynaptic axon of the lobster neuromuscular junction depends on both Na+ and Ca2+.