On the repetitive discharge in myotonic muscle fibres

RH Adrian, SH Bryant - The Journal of Physiology, 1974 - Wiley Online Library
RH Adrian, SH Bryant
The Journal of Physiology, 1974Wiley Online Library
1. Muscle fibres from myotonic goats respond to injected constant currents with a train of
action potentials. If the number of action potentials in an evoked train exceeds 10–15,
stopping the current does not stop the repetitive firing of action potentials. 2. Normal muscle
fibres (goat) in a chloride‐free Ringer respond in the same way to constant current. 3. In the
absence of self‐maintained activity both myotonic fibres and normal fibres in chloride‐free
Ringer show an after‐depolarization which is proportional to the number of driven impulses …
1. Muscle fibres from myotonic goats respond to injected constant currents with a train of action potentials. If the number of action potentials in an evoked train exceeds 10–15, stopping the current does not stop the repetitive firing of action potentials.
2. Normal muscle fibres (goat) in a chloride‐free Ringer respond in the same way to constant current.
3. In the absence of self‐maintained activity both myotonic fibres and normal fibres in chloride‐free Ringer show an after‐depolarization which is proportional to the number of driven impulses. The half‐time for the decay of this after‐potential is about 0·5 sec.
4. Tubular potassium accumulation resulting from the initially driven activity and the known low chloride conductance of myotonic muscle fibres appear to account for the initiation of the myotonic discharge.
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