Hostname: page-component-7c8c6479df-xxrs7 Total loading time: 0 Render date: 2024-03-29T11:01:43.358Z Has data issue: false hasContentIssue false

Effects of reactive oxygen species on aspects of excitation-contraction coupling in chemically skinned rabbit diaphragm muscle fibres

Published online by Cambridge University Press:  31 July 2001

G. M. Darnley
Affiliation:
Centre for Exercise Science and Medicine, Institute of Biomedical and Life Sciences, University of Glasgow, Glasgow G12 8QQ and School of Biology, University of Leeds, Leeds LS2 9JT, UK
A. M. Duke
Affiliation:
Centre for Exercise Science and Medicine, Institute of Biomedical and Life Sciences, University of Glasgow, Glasgow G12 8QQ and School of Biology, University of Leeds, Leeds LS2 9JT, UK
D. S. Steele
Affiliation:
Centre for Exercise Science and Medicine, Institute of Biomedical and Life Sciences, University of Glasgow, Glasgow G12 8QQ and School of Biology, University of Leeds, Leeds LS2 9JT, UK
N. G. MacFarlane
Affiliation:
Centre for Exercise Science and Medicine, Institute of Biomedical and Life Sciences, University of Glasgow, Glasgow G12 8QQ and School of Biology, University of Leeds, Leeds LS2 9JT, UK
Get access

Abstract

Oxidants have been suggested to enhance contractile function in unfatigued muscle. In this study we aimed to determine the effect of oxidants on 'chemically skinned' diaphragm muscle fibre bundles. The sarcoplasmic reticulum and contractile proteins were exposed to superoxide anions (O2-) and hydrogen peroxide (H2O2) under controlled conditions. Application of O2- initially increased maximum Ca2+-activated force but subsequently reduced maximum Ca2+-activated force without altering myofilament Ca2+ sensitivity. Unlike myocardium, caffeine-induced Ca2+ release from the sarcoplasmic reticulum was also inhibited by O2- exposure in diaphragm fibre bundles. Application of H2O2 also increased maximum Ca2+-activated force but had additional effects on resting tension (which increased to 25 % of the control maximum Ca2+-activated force). H2O2 was without effect on myofilament Ca2+ sensitivity or caffeine-induced Ca2+ release from the sarcoplasmic reticulum. These data demonstrate that oxidants can potentiate contractile force in the diaphragm through a direct action on the contractile proteins. The potentiation of force is not sustained, however, and under these conditions the detrimental effects of O2- on Ca2+ release from the sarcoplasmic reticulum combined with the effects of oxidants on the contractile proteins will ultimately compromise excitation-contraction coupling in the diaphragm. Experimental Physiology (2001) 86.2, 161-168.

Type
Research Article
Copyright
© The Physiological Society 2001

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)