Effect of myosin ATPase inhibition during tetanic stimulation on subcellular compartmentalized glycogen metabolism. (A) Force production during repeated tetanic stimulations in control muscles (red) and in muscles with the myosin ATPase inhibited (BTS + Bleb; yellow) shown as mean and SD. n = 12–13 muscles. (B) Muscle homogenate glycogen concentration shown as mean with 95% confidence interval. n = 9–13 rats. (C) Muscle homogenate lactate concentration shown as geometric mean with 95% confidence interval. n = 9–13 rats. (D, F, and H) Single-fiber values of glycogen in three distinct subcellular pools: intermyofibrillar, intramyofibrillar, and subsarcolemmal. Data are shown as box plots displaying the first and third quartiles and split by the median. n = 27–39 fibers from 9 to 13 muscles. (E, G, and I) Point estimates with 95% confidence interval from linear mixed effect model on square root-transformed data from D. (J and K) Illustrations of the spatial association between SR Ca²⁺ ATPases situated at the SR membrane (orange in F) and intermyofibrillar glycogen, and between the myosin ATPases (orange in G) and inter- and intramyofibrillar glycogen. Interaction or main effects were tested using linear mixed-effect model on square root–transformed data with tetanic stimulation and myosin ATPase inhibitors as fixed effects and rat ID as random effect. P values for two-way interactions were 0.008, 0.001, 0.395, 0.039, and 0.045 for intermyofibrillar, intramyofibrillar, subsarcolemmal glycogen, homogenate glycogen, and homogenate lactate, respectively.