Force generated by myosin cross-bridges is reduced in myofibrils exposed to ROS/RNS.

In this study, we examined the effects of peroxynitrite (ONOO-) on the contractile properties of individual skeletal muscle myofibrils by monitoring myofibril-induced displacements of an atomic force cantilever upon activation and relaxation. The isometric force decreased by approximately 50% in myofibrils treated with the ONOO-donor (SIN-1) or directly with ONOO-, which was independent of the cross-bridge abundancy condition (i.e. rigor or relaxing condition) during SIN-1 or ONOO-treatment. The force decrease was attributed to an increase in the cross-bridge detachment rate (gapp) in combination with a conservation of the force redevelopment rate (kTr), hence an increase in the population of cross-bridges transitioning from force-generating to non-force-generating cross-bridges during steady-state. Taken together, the results of this study provide important information of how ROS/RNS affect myofibrillar force production which may be of importance for conditions where increased oxidative stress is part of the pathophysiology.
PMID: 31553646 [PubMed - as supplied by publisher]

Source: Am J Physiol Cell Ph... - September 24, 2019 Category: Cytology Authors: Persson M, Steinz MM, Westerblad H, Lanner JT, Rassier DE Tags: Am J Physiol Cell Physiol Source Type: research