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An analysis of miniature synaptic events recorded from locust muscle--variations in amplitude and time courses.

Authors
  • Fahim, M A
Type
Published Article
Journal
Cellular and molecular biology
Publication Date
May 01, 1992
Volume
38
Issue
3
Pages
231–241
Identifiers
PMID: 1611654
Source
Medline
License
Unknown

Abstract

A study of miniature post-synaptic potentials (min. e.p.s.p.'s) in metathoracic extensor tibiae muscle fibres at neuromuscular junctions of adult locusts (Schistocerca gregaria) has been undertaken. Extracellular min. e.p.s.p.'s recorded from single junctional sites and their "marked" intracellular min. e.p.s.p. counterparts varied both in time course and amplitude and at many sites a small proportion of abnormal miniatures were observed, i.e., of large amplitude and/or of long duration. Positive correlations between the rise times and 1/2-decay times of the extracellular min. e.p.s.p.'s and between rise times and amplitudes and 1/2-decay times and amplitudes of "marked" intracellular events were found. Comparison of results obtained from differently innervated muscle fibres demonstrates that the occurrence of abnormal miniatures is independent of the type of innervation i.e., "fast" or "slow" excitatory motoneurons. Mechanisms that lead to the occurrence of abnormal miniatures are discussed in relation to the presence of large vesicles in the terminals of the excitatory motoneurons but the occurrence of these events could equally well be explained by the "post-synaptic saturation hypothesis".

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