Key result
Raising inorganic phosphate concentration by 10 mM reduced isometric force and the number of myosin motors by 40-50% but did not influence the dependence on shortening velocity of motor number and strain.
Population
10 glycerinated skinned fibre segments from the psoas muscle of 3 adult male New Zealand White rabbits
Comparison
Steady shortening at different velocities and… vs Control conditions (no added Pi)
Design
Preclinical
Authors
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May reduce force in Pi-elevated states; extends cross-bridge models but leaves in vivo cardiac relevance open.
The study provides a molecular explanation for the relation between the rate of energy liberation and shortening velocity during muscle contraction by showing that Pi and ADP release rates increase as the motor progresses through the working stroke.
Caremani et al. (2015) studied this question. Raising inorganic phosphate (Pi) concentration vs. Control conditions (no added Pi) was evaluated on Number and strain of myosin motors interacting during steady shortening at different velocities. Raising inorganic phosphate concentration by 10 mM reduced isometric force and the number of myosin motors by 40-50% but did not influence the dependence on shortening velocity of motor number and strain.
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