Electron microscopic recording of ATP-induced cross-bridge movement in living thick filament using the gas environmental chamber

Abstract

The most straightforward approach to the amplitude of cross-bridge powerstroke in muscle is to record ATP-induced cross-bridge movement in living thick filaments, using the gas environmental chamber(Sugi et al. PNAS 94:4378-4382,1997). To determine the direction of cross-bridge movement with respect to the center of the thick filament, large bipolar thick filaments are prepared by slowly polymerizing rabbit skeletal muscle myosin. Gold particles are attached to the cross-bridges to serve as position markers. Filament images are recorded on the imaging plate under a magnification of 7,000-10,000 diameters. Position of the gold particles does not change appreciably with time, indicating that the time-averaged cross-bridge position is constant. Oniontophoretic ATP application, the cross-bridges are found to move by 7-8nm parallel to the filament axis. [J Physiol Sci. 2007;57 Suppl:S128]