Staircase potentiation in isolated frog skeletal muscle: power spectral analysis of the evoked compound muscle action potential.
1. The mechanical and electrophysiological effects of repetitive, low-frequency electrical stimulation on paired sartorii muscles from small male frogs have been investigated, in vitro. 2. Stimulation for 90 sec at 5 Hz resulted in a progressive rise (staircase) than fall (fatigue) in peak twitch tension. 3. The root mean square amplitude, peak-to-peak amplitude, conduction velocity and mean power frequency of evoked compound muscle action potentials (CMAPs) decreased over the stimulation period. 4. Results suggest that alterations in the shape of the CMAP during repetitive stimulation may contribute to the staircase phenomenon.
Barnes
W S
WS
Department of Health and Kinesiology, Texas A&M University, College Station 77843.
Williams
J H
JH
D000200:Action Potentials / Q000502:physiology; D000818:Animals; D004558:Electric Stimulation; D005071:Evoked Potentials / Q000502:physiology; D006863:Hydrogen-Ion Concentration; D009119:Muscle Contraction / Q000187:drug effects; D009132:Muscles / Q000502:physiology*; D011894:Rana pipiens