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Delayed release of transmitter at the frog neuromuscular junction
Author(s) -
Rahamimoff R.,
Yaari Y.
Publication year - 1973
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.1973.sp010084
Subject(s) - neuromuscular junction , divalent , extracellular , chemistry , biophysics , ion , intracellular , neuromuscular transmission , endocrinology , biochemistry , medicine , biology , neuroscience , organic chemistry
1. After the end‐plate potential (e.p.p.) there is an increase in the frequency of the miniature e.p.p.s. This delayed release of transmitter was studied at the frog neuromuscular junction, using conventional intracellular and extracellular recording techniques. E.p.p. amplitude was kept subthreshold by subnormal concentrations of activating divalent ions. 2. The ratio delayed release: initial release had values between 2 and 140%, depending on the experimental conditions; it decreased with an increase in Ca concentration and quantal content. 3. Delayed release is larger at low temperature than at room temperature. 4. Delayed release is statistically independent of the amplitude of the preceding e.p.p. 5. The time course of the decay of the delayed release is monotonic when strontium is the activating divalent ion; it shows a ‘dip’ in more than 50% of the cases when Ca activated release. 6. The results were discussed in terms of the residual Ca ion hypothesis.