di Prampero P E, Boutellier U, Marguerat A
Department of Physiology, Centre Médical Universitaire, Geneva, Switzerland.
Pflugers Arch. 1988 Oct;412(5):455-61. doi: 10.1007/BF00582533.
Mechanical work, ATP, ADP, PC, free creatine and lactate concentrations were determined on IAA poisoned frog sartorii tetanically stimulated in humidified N2 at 10 degrees C in isotonic conditions (0.25 or 0.45 Po). Tetanus duration was 0.35 s, number of tetani was varied from 0 (rest) to 25 (exhaustion). The mechanical work performed per mole ATP + PC split (WP) amounted on the average to 16.7 kJ/mol. It was observed, however, that WP increased from about 13 to about 24 kJ/mol with decreasing ATP concentration from about 2 (resting value) to about 1 mumol/g and that this decrease in ATP was associated with a decrease of the shortening (and relaxation) speed of the muscle to about 30% of the values observed on the first tetanus. It is concluded that the thermodynamic efficiency of muscle contraction, calculated from the ratio of WP* (measured) to the thermodynamic affinity (free energy change) of ATP hydrolysis (estimated) increases from about 0.3 to about 0.5 with decreasing ATP concentration and shortening speed.
在10℃、湿度饱和的氮气环境中，在等渗条件（0.25或0.45Po）下，对受吲哚乙酸中毒的青蛙缝匠肌进行强直刺激，测定其机械功、三磷酸腺苷（ATP）、二磷酸腺苷（ADP）、磷酸肌酸（PC）、游离肌酸和乳酸浓度。强直收缩持续时间为0.35秒，强直收缩次数从0（静息）到25（疲劳）不等。每摩尔ATP + PC分解所做的机械功（WP）平均为16.7千焦/摩尔。然而，观察到随着ATP浓度从约2（静息值）降至约1微摩尔/克，WP从约13千焦/摩尔增加到约24千焦/摩尔，并且ATP的这种降低与肌肉缩短（和舒张）速度降至首次强直收缩时观察值的约30%有关。得出的结论是，根据测量的WP*与ATP水解的热力学亲和力（估计的自由能变化）之比计算得出的肌肉收缩热力学效率，随着ATP浓度和缩短速度的降低，从约0.3增加到约0.5。
