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Miniature potentials in denervated slow muscle fibres of the frog
Author(s) -
Miledi R.,
Stefani E.
Publication year - 1970
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.1970.sp009161
Subject(s) - denervation , fibre type , anatomy , fast twitch muscle , chemistry , biophysics , time constant , nerve fibre , muscle fibre , biology , skeletal muscle , electrical engineering , engineering
1. Pyriformis and iliofibularis muscles of the frog were studied with micro‐electrodes. Both muscles contain a mixture of fast and slow muscle fibres, which can be distinguished by differences in their miniature end‐plate potentials (min.e.p.p.s). 2. In addition, the membrane time constant of fast fibres is < 20 msec, while that of slow fibres is > 200 msec. 3. The characteristic difference in time constant persisted after denervation and allowed the identification of fibre type. 4. Denervated slow fibres had min.e.p.p.s of variable time courses and skew amplitude distributions. Their frequency was lower than in normally innervated fibres, and could be increased by hypotonic solutions. 5. In analogy with similar observations made previously in fast muscle fibres, it is suggested that after nerve degeneration the Schwann cells of small motor nerve fibres release packages of transmitter which give rise to min.e.p.p.s.