Rigor bonds cause reduced sarcomeric volume in skinned porcine skeletal muscle under PSE-like conditions

Effects of rigor cross-bridge attachment on water holding in PSE-like conditions were investigated. A new model using permeabilised/skinned porcine longissimus thoracis et lumborum muscle fibres was established to study effects of varied pH, temperature and the presence of rigor bonds on the muscle fibre structure. Preparations were exposed during 30 min to different temperatures (22 and 38 °C) and pH (7.0 and 5.5) in relaxed and rigor states, followed by evaluation of active force and filament lattice spacing (using small angle X-ray scattering) at standard pH (7.0) and temperature (22 °C) conditions. A significant reduction of active force and filament spacing was observed after treatment in rigor at denaturing (38 °C, pH 5.5) conditions. The present study show that rigor bond attachment under denaturing conditions leads to a compressed interfilamental space, loss of sarcomeric water and affected contractile function.