Changes of Muscle Fibre Properties Under Physiological and Pathological Conditions

Abstract

Biochemical measurements have shown that the metabolism of the whole muscle changes under varying experimental conditions (Simoneau 1990; Schantz et al. 1997; Taylor and Bachman 1999; Prior et al. 2001). Moreover, it was observed that the metabolic properties of the muscle fibre changed earlier and more quickly than its contractility (Hoppeler 1990). However, biochemical measurements do not give any information about the extent of the metabolic changes in a certain fibre type or about the share of a certain fibre type of the measured activity changes of the whole muscle respectively. At this point, cytophotometrical measurements of enzyme activities in the metabolically characterized fibres are necessary. The enzymes which were suitable markers for fibre typing (Sect. 4.2.) are at the same time useful for characterizing metabolic changes of the fibre under changing conditions. Changes of the activity quotient GPDH/SDH of a fibre type characterize changes of the metabolic profile of this fibre type. This means that cytophotometrical measurements of the three chosen enzyme activities in muscle sections from different experimental groups simultaneously provide fibre typing in SO, FOG and FG fibres and changes of the metabolic profile in these fibre types.