The method of kinetic analysis of the relaxation phase of the mechanical response of the smooth muscle previously proposed by Burdyga and Kosterin was applied to study the dynamics of the decay of oxytocin-induced calcium transients in cytosol of the rat myometrium smooth muscle cell detected by a fluorescence signal generated by a calcium-sensitive probe fluo-4 using a laser scanning confocal microscope. The experimental data were well linearized in the coordinates ln [(F_m – F)/F] vs lnt (F and F_m are the current fluorescence intensity of the calcium probe and the fluorescence intensity at the maximum of the calcium transient, respectively, while t is the time). The empirical parameters n and τ were determined by which the maximal normalized relaxation rate V_n was calculated for five different ROIs (regions of interest) in the myocyte cytosol. It proved to be almost the same for all ROIs. The maximal normalized relaxation rate calculated from the fluorescence intensity was always lower than that calculated from the corresponding calcium concentration, i.e. the cytosolic Ca²⁺ concentration in the relaxation phase decreases faster than the corresponding fluorescence intensity. The value of the maximal normalized relaxation rate calculated both from the fluorescence intensity and from the force of oxytocin-induced contractions of isolated rat uterus longitudinal smooth muscles (according to Tsymbalyuk and Kosterin) was exactly the same. This indicates that in the relaxation phase, the decreasing curves of both the fluorescence intensity and the contraction forces coincide.

Burdyga 和 Kosterin 先前提出的平滑肌机械反应松弛阶段的动力学分析方法被应用于研究催产素诱导的大鼠子宫肌层平滑肌细胞胞质溶胶中钙瞬变衰减的动力学。使用激光扫描共聚焦显微镜由钙敏感探针fluo-4产生的荧光信号。实验数据在坐标 ln [( F _m  –  F )/ F ] vs ln t ( F和F _m分别是钙探针的当前荧光强度和钙瞬变最大值处的荧光强度，而t是时间）。经验参数n和τ由其计算出肌细胞胞质溶胶中五个不同 ROI（感兴趣区域）的最大归一化松弛率V _n。事实证明，所有投资回报率几乎都相同。从荧光强度计算的最大归一化弛豫率总是低于从相应的钙浓度计算的，即细胞溶质 Ca ²⁺弛豫相中的浓度比相应的荧光强度下降得更快。根据荧光强度和催产素诱导的离体大鼠子宫纵向平滑肌收缩力（根据 Tsymbalyuk 和 Kosterin）计算的最大归一化松弛率的值完全相同。这表明在弛豫阶段，荧光强度和收缩力的下降曲线重合。