Mahler M, Louy C, Homsher E, Peskoff A
J Gen Physiol. 1985 Jul;86(1):105-34. doi: 10.1085/jgp.86.1.105.
Previously we tested the validity of the one-dimensional diffusion equation for O2 in the excised frog sartorius muscle and used it to measure the diffusion coefficient (D) for O2 in this muscle and the time course of its rate of O2 consumption (Qo2) after a tetanus (Mahler, 1978, 1979, J. Gen. Physiol., 71:533-557, 559-580, 73:159-174). A transverse section of the frog sartorius is in fact well fit by a hemi-ellipse with width divided by maximum thickness averaging 5.1 +/- 0.2. Using the previous techniques with the two-dimensional diffusion equation and this hemi-elliptical boundary yields a value for D that is 30% smaller than reported previously; the revised values at 0, 10, and 22.8 degrees C are 6.2, 7.9, and 10.8 X 10(-6) cm2/s, respectively. After a tetanus at 20 degrees C, Qo2 rose quickly to a peak and then declined exponentially, with a time constant (tau) approximately 15% faster than that reported previously; tau averaged 2.1 min in Rana temporaria and 2.6 min in Rana pipiens. A technique was devised to measure the solubility (alpha) of O2 in intact, respiring muscles, and yielded alpha (muscle)/alpha (H2O) = 1.26 +/- 0.04. With these modifications, the values for O2 consumption obtained with the diffusion method were in agreement with those measured by the direct method of Kushmerick and Paul (1976, J. Physiol. [Lond.]., 254:693-709). Using results from both methods, at 20 degrees C the ratio of phosphorylcreatine split during a tetanus to O2 consumption during recovery ranged from 5.2 to 6.2 mumol/mumol, and postcontractile ATP hydrolysis was estimated to be 13.6 +/- 4.1 (n = 3) nmol/mumol total creatine.
此前，我们检验了一维扩散方程对离体青蛙缝匠肌中氧气的有效性，并利用该方程测量了氧气在这块肌肉中的扩散系数（D）以及强直收缩后其氧气消耗速率（Qo2）的时间进程（马勒，1978年、1979年，《普通生理学杂志》，71:533 - 557，559 - 580，73:159 - 174）。青蛙缝匠肌的横切面实际上很好地拟合了一个半椭圆，其宽度除以最大厚度的平均值为5.1±0.2。使用先前的技术结合二维扩散方程以及这个半椭圆边界，得到的D值比之前报道的小30%；在0、10和22.8摄氏度下修正后的值分别为6.2、7.9和10.8×10⁻⁶平方厘米/秒。在20摄氏度下强直收缩后，Qo2迅速上升至峰值，然后呈指数下降，时间常数（τ）比之前报道的快约15%；在欧洲林蛙中τ平均为2.1分钟，在北美牛蛙中为2.6分钟。设计了一种技术来测量氧气在完整的、进行呼吸的肌肉中的溶解度（α），得到α（肌肉）/α（水） = 1.26±0.04。有了这些修正，用扩散法得到的氧气消耗值与库什梅里克和保罗的直接法测量值（1976年，《生理学杂志》[伦敦]，254:693 - 709）一致。使用两种方法的结果，在20摄氏度下，强直收缩期间磷酸肌酸的分解与恢复期间氧气消耗的比率在5.2至6.2微摩尔/微摩尔之间，收缩后ATP水解估计为13.6±4.1（n = 3）纳摩尔/微摩尔总肌酸。
