Barr L, Gu F J
Biophys J. 1987 Jun;51(6):895-904. doi: 10.1016/S0006-3495(87)83417-3.
The time courses of isometrically recorded photomechanical responses of isolated sphincter pupillae of Rana pipiens can be accurately predicted by a set of differential equations derived from phosphorylation theory of smooth muscle contraction. We compared actual light-stimulated contractions with calculated ones over a wide range of stimulus intensities (56-fold) and durations (0.4-4.0 s). The hypothetical Ca++-calmodulin-myosin light chain kinase cascade acts as a "valve" to control the flow of ATP through a phosphorylation-dephosphorylation cycle. When the rate of flow of ATP through the phosphorylation-dephosphorylation cycle is increased, the percentage of phosphorylated myosin increases. The time courses of the concentrations of phosphorylated myosin during different responses are seen to be functions of the time courses of the opening and closing of the coupling cascade "valve." The calculations predict experimentally measurable intermediate variables, which can aid the investigation of the application of quantitative phosphorylation theory to amphibian sphincter pupillae and to smooth muscle in general.
源自平滑肌收缩磷酸化理论的一组微分方程，能够准确预测豹蛙离体瞳孔括约肌等长记录的光机械反应的时间进程。我们在很宽的刺激强度范围（56倍）和持续时间范围（0.4 - 4.0秒）内，比较了实际光刺激收缩与计算得到的收缩情况。假设的Ca++ - 钙调蛋白 - 肌球蛋白轻链激酶级联反应起到一个“阀门”的作用，通过磷酸化 - 去磷酸化循环来控制ATP的流动。当ATP通过磷酸化 - 去磷酸化循环的流动速率增加时，磷酸化肌球蛋白的百分比增加。在不同反应过程中，磷酸化肌球蛋白浓度的时间进程被视为耦合级联“阀门”开闭时间进程的函数。这些计算预测了实验中可测量的中间变量，这有助于研究定量磷酸化理论在两栖类瞳孔括约肌以及一般平滑肌中的应用。
