Velocity recovery cycles of human muscle action potentials and their sensitivity to ischemia

Z'graggen, Werner J; Bostock, Hugh (2009). Velocity recovery cycles of human muscle action potentials and their sensitivity to ischemia. Muscle & nerve, 39(5), pp. 616-26. New York, N.Y.: John Wiley & Sons 10.1002/mus.21192

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This study was undertaken to test whether recovery cycle measurements can provide useful information about the membrane potential of human muscle fibers. Multifiber responses to direct muscle stimulation through needle electrodes were recorded from the brachioradialis of healthy volunteers, and the latency changes measured as conditioning stimuli were applied at interstimulus intervals of 2-1000 ms. In all subjects, the relative refractory period (RRP), which lasted 3.27 +/- 0.45 ms (mean +/- SD, n = 12), was followed by a phase of supernormality, in which the velocity increased by 9.3 +/- 3.4% at 6.1 +/- 1.3 ms, and recovered over 1 s. A broad hump of additional supernormality was seen at around 100 ms. Extra conditioning stimuli had little effect on the early supernormality but increased the later component. The two phases of supernormality resembled early and late afterpotentials, attributable respectively to the passive decay of membrane charge and potassium accumulation in the t-tubules. Five minutes of ischemia progressively prolonged the RRP and reduced supernormality, confirming that these parameters are sensitive to membrane depolarization. Velocity recovery cycles may provide useful information about altered muscle membrane potential and t-tubule function in muscle disease. Muscle Nerve, 2008.

Item Type:	Journal Article (Original Article)
Division/Institute:	04 Faculty of Medicine > Department of Head Organs and Neurology (DKNS) > Clinic of Neurology
UniBE Contributor:	Z'Graggen, Werner Josef, Bostock, Hugh
ISSN:	0148-639X
ISBN:	19229874
Publisher:	John Wiley & Sons
Language:	English
Submitter:	Factscience Import
Date Deposited:	04 Oct 2013 15:06
Last Modified:	05 Dec 2022 14:20
Publisher DOI:	10.1002/mus.21192
PubMed ID:	19229874
Web of Science ID:	000265450000008
URI:	https://boris.unibe.ch/id/eprint/28730 (FactScience: 127929)