Faculty Collaboration Database

Role of sarcolemma action potentials and excitability in muscle fatigue. J Appl Physiol (1985) 1994 May;76(5):2157-62

Date

05/01/1994

Pubmed ID

8063681

DOI

10.1152/jappl.1994.76.5.2157

Scopus ID

2-s2.0-0028305080 (requires institutional sign-in at Scopus site)   61 Citations

Abstract

The purposes of this study were to characterize the alterations in the sarcolemma action potential (AP) waveform and sarcolemma excitability as a result of fatiguing stimulation of the frog semitendinosus muscle and to relate these changes to the decrease in the force-generating ability of the muscle. Trains of APs were recorded before and after stimulation (100-ms trains, 150 Hz, 1/s for 5 min). The resting membrane potential (RMP), AP overshoot (OS), and duration at 50% of peak magnitude (DUR) were -84.3 +/- 2.0 mV, 19.5 +/- 1.9 mV, and 1.3 +/- 0.1 ms, respectively, before stimulation. The stimulation protocol caused RMP to depolarize to -75.1 +/- 2.0 mV, OS to fall to 7.3 +/- 1.9 mV, and DUR to increase to 2.5 +/- 0.4 ms. RMP and OS recovered fully in 5 min after the cessation of stimulation, whereas DUR was still prolonged. Before the stimulation protocol, AP frequency matched the stimulation frequency at all stimulation rates < or = 150 Hz. At 200-Hz stimulation, AP frequency was 192 +/- 6 Hz. After 5 min of stimulation, AP frequency matched the stimulation frequency only at < or = 60 Hz. At 100-, 150-, and 200-Hz stimulation, AP frequencies were 89 +/- 8, 84 +/- 17, and 79 +/- 15 Hz, respectively. Because of a decreased fusion frequency at fatigue, the fall in the sarcolemma AP frequency did not contribute to the decreased force. The stimulation-induced alterations in the AP waveform were moderate and unlikely to have caused fatigue. However, the alterations in AP may have been more extreme in the depths of the transverse tubules.

Author List

Balog EM, Thompson LV, Fitts RH

Author

Robert Fitts PhD Professor in the Biological Sciences department at Marquette University

MESH terms used to index this publication - Major topics in bold

Action Potentials
Animals
Electric Stimulation
In Vitro Techniques
Membrane Potentials
Microelectrodes
Muscle Contraction
Muscles
Rana pipiens
Sarcolemma