Fig. 6

Time course of changes of metabolites after tetanic contractions of frog muscles studied by ³¹P NMR. a Recovery of frog muscles from contractions studied by using the chamber apparatus for ³¹P NMR shown in Fig. 5a. Four frog sartorius muscles were repeatedly stimulated for 25 s every 56 min and spectra accumulated into eight bins of 7 min each. The graph shows how PCr (+), P_i (×) and sugar P (Δ) varied. The ordinates show the resonance peak areas as multiples of the mean area for the β ATP peak. The right-hand scale applies to PCr. The exponential curve drawn through the PCr points has a T _1/2 of 9.1 min. Dawson, Gadian and Wilkie [22]. b The changes of PCr concentrations associated with 10-s isometric tetanus using chamber apparatus shown in Fig. 5b with sixteen dorsal heads of bullfrog semitendinosus muscles at 4 °C. Note that the time resolution is greatly improved compared to the results in a. The curve is the same exponential for P_i in c. Kawano, Tanokura and Yamada [26]. c Changes in P_i concentrations in the same experiments and muscle preparations as in b. The curve shows a single exponential fitted to the time course of the recovery of P_i (τ 37.5 min; T _1/2 26 min). Kawano, Tanokura and Yamada [26]