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Endotoxin alters spontaneous transmitter release at the frog neuromuscular junction
Author(s) -
Person Robert J.
Publication year - 1977
Publication title -
journal of neuroscience research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.72
H-Index - 160
eISSN - 1097-4547
pISSN - 0360-4012
DOI - 10.1002/jnr.490030107
Subject(s) - neuromuscular junction , biophysics , chemistry , transmitter , conductance , neuromuscular transmission , neuroscience , biology , endocrinology , channel (broadcasting) , mathematics , combinatorics , electrical engineering , engineering
The direct neurotoxic effects of E. coli endotoxin (ETX) on spontaneous transmitter release were tested at the frog sartorius muscle neuromuscular junction. Spontaneous transmitter release was monitored by intracellularly recording miniature end‐plate potentials (MEPPs). Junctions were continuously exposed to standard concentrations of 10μg/ml of 3 ETX sample, 2 of which produced a significant elevation of MEPP frequency followed by a decline of frequency to very low rates. The third ETX sample, known to have a decreased canine lethality, was with out effect on MEPP frequency. No significant changes in MEPP amplitude were evident. The rate of change in MEPP frequency, but not the peak frequency, was reduced by lowering ETX concentrations. Alterations in MEPP frequency induced by ETX were prevented by removing Ca ++ and antagonized by high [k + ] out. The results suggest that ETX alters ion conductance channels, particularly those for Ca ++ , in the presynaptic terminal membrane.