IMPROVEMENT OF THE MEASUREMENTS ON SKINNED MUSCLE-FIBERS BY FIXATION OF THE FIBER ENDS WITH GLUTARALDEHYDE

Experiments with activated skinned muscle fibre segments are limited b y the structural and mechanical instability of the preparations. The p resent study shows that fixation of the muscle fibre ends with glutara ldehyde significantly improves the reliability of such experiments. We tested the effects of a specific glutaraldehyde fixation technique on the structural stability and the mechanical properties of skinned rat and rabbit skeletal muscle fibres in an approach where the fibre segm ents are attached to the apparatus by gluing. Preparations with fixed and unfixed ends were compared. During the first few minutes of maxima l activation, fibres with fixed and unfixed ends exhibited similar mec hanical properties to one another, suggesting that our fixation proced ure selectively impregnates the fibre ends without contaminating the r emaining active fibre part. During prolonged maximal activations (3-60 min), preparations with fixed ends exhibited a better stability, both in the sarcomere length signal (detected by laser diffraction) and in the unloaded shortening velocity. Thus, our technique of muscle fibre end fixation caused a substantial improvement in the mechanical measu rements on skinned muscle preparations. (C) Chapman & Hall Ltd.