Crossbridge recruitment by stretching does not invalidate force spectroscopy experiments in living skeletal muscle fibres.

摘要

In a paper recently published in The Journal of Physiology, Fusi et al. (2010) report that the stiffness increase of activated single skeletal muscle fibres, following a fast stretch, is due to a rapid recruitment of new bridges. According to Fusi et al. this effect appears to nullify the validity of the method used by Colombini et al. (2007) to investigate the properties of the actomyosin bond in living muscle fibres. Below, I will show that this is not the case. According to the theory of bond rupture (Bell, 1978) a mechanical force applied to a non-covalent chemical bond increases its detachment rate constant leading to a fast rupture.