Proceedings of The Physiological Society
King's College London (2009) Proc Physiol Soc 14, C6
The effects of hydrogen peroxide on contractile properties of skinned muscle fibres of the rat: a model for ageing?
S. F. Gilliver1, J. Rittweger1, D. A. Jones1, H. Degens1
1. IRM, Manchester Metropolitan University, Manchester, United Kingdom.
Oxidative damage to tissues is thought to play a role in the age-related changes in muscle function. Several groups have found that incubating single skinned muscle fibres with hydrogen peroxide (H2O2) leads to reduced calcium sensitivity and loss of force (1) and a decrease in maximum shortening velocity (2). As yet, no study has determined how the capacity to generate power. Maximum instantaneous power is determined by the maximum velocity of unloaded shortening (Vmax), isometric force (Po), and the curvature (a/Po) of the force-velocity relationship. The purpose of this study was therefore to examine the effects of oxidative damage the determinants of power. Rats were killed humanely at 8 weeks, the soleus muscle excised and skinned single fibres prepared using established procedures (3,4). Fibres were activated in pCa 4.5 solutions at 15°C and underwent a series of isotonic shortening steps (5). Fifteen fibres were subjected to an initial series of contractions and then again after 4-min incubation in 50 mM H2O2. Control fibres (n = 6) were subjected to the same testing procedure except that they were incubated in normal relaxing solution between tests. Incubation in H2O2 caused a 20% and 25% drop in Po and Vmax, respectively, while peak power fell approximately 34% (Fig 1). In contrast, ,a/Po rose 18% (decreased curvature), tending to maintain power. The control fibres showed only small and non-significant changes. The novel feature of these results is that a/Po increased with oxidative damage. Old muscle fibres are reported to have low shortening velocity (4) but it is not known whether they have high values of a/Po. If this proves to be the case it would suggest that H2O2 treatment is a useful model for examining the reported age-related changes in contractile characteristics.
Where applicable, experiments conform with Society ethical requirements