Signal transduction in smooth muscle - Selected contribution: Time course and heterogeneity of contractile responses in cultured human airway smooth muscle cells
Signal transduction in smooth muscle - Selected contribution: Time course and heterogeneity of contractile responses in cultured human airway smooth muscle cells
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DOI：
10.1152/jappl.2001.91.2.986
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发表时间：
2001-08-01
影响因子：
3.3
通讯作者：
Fredberg, JJ
中科院分区：
文献类型：
--
作者：
Fabry, B;Maksym, GN;Fredberg, JJ
我们测量了培养的单个人气道平滑肌（HASM）细胞对收缩和放松激动剂反应的时间过程和异质性。为此，我们开发了一种基于磁扭转细胞术的微流变仪，并结合了一种新型的光学检测系统。包覆Arg-Gly-Asp肽的铁磁珠（4.5 μ m）与细胞表面的整合素结合。这些珠子在0.75 Hz的正弦变化磁场中被扭曲。用相位同步摄像机记录振荡头位移。存储模量（胞体刚度；G′）、损耗模量（摩擦；G′）和滞回率（G′与G′之比）的时间分辨率为1.3 s。添加组胺（100 muM）后5 s内，G′增加了2.2倍，G′增加了3.0倍，h从0.27瞬间增加到0.34。到20s， eta降至0.25，而G‘和G’仍高于基线。与缓激素（1mum）的结果相当。在细胞中测量到的G‘， G’ '和eta的变化与完整肌肉条相似，但小于报道的变化。当我们加入松弛激动剂二丁基cAMP （1 mM）消融基线张力时，G′在5分钟内下降了3.3倍。使用松弛和收缩激动剂，G'可以通过7.3倍的收缩范围进行操纵。细胞群表现出基线刚度的对数正态分布（几何SD = 2.8）和对收缩和放松激动剂的异质反应，部分归因于细胞之间基线张力的可变性。然而，细胞的总收缩范围（从最大放松到最大刺激）与基线刚度无关。我们得出的结论是，培养的HASM细胞对收缩和放松激动剂表现出明确的（尽管是异质的）反应，并表达了在组织水平上观察到的收缩反应的基本机械特征。
We measured the time course and heterogeneity of responses to contractile and relaxing agonists in individual human airway smooth muscle (HASM) cells in culture. To this end, we developed a microrheometer based on magnetic twisting cytometry adapted with a novel optical detection system. Ferromagnetic beads (4.5 mum) coated with Arg-Gly-Asp peptide were bound to integrins on the cell surface. The beads were twisted in a sinusoidally varying magnetic field at 0.75 Hz. Oscillatory bead displacements were recorded using a phase-synchronized video camera. The storage modulus (cell stiffness; G'), loss modulus (friction; G"), and hysteresivity (eta; ratio of G" to G') could be determined with a time resolution of 1.3 s. Within 5 s after addition of histamine (100 muM), G' increased by 2.2-fold, G" increased by 3.0-fold, and h increased transiently from 0.27 to 0.34. By 20 s, eta decreased to 0.25, whereas G' and G" remained above baseline. Comparable results were obtained with bradykinin (1 muM). These changes in G', G", and eta measured in cells were similar to but smaller than those reported for intact muscle strips. When we ablated baseline tone by adding the relaxing agonist dibutyryl cAMP (1 mM), G' decreased within 5 min by 3.3-fold. With relaxing and contracting agonists, G' could be manipulated through a contractile range of 7.3-fold. Cell populations exhibited a log-normal distribution of baseline stiffness (geometric SD = 2.8) and a heterogeneous response to both contractile and relaxing agonists, partly attributable to variability of baseline tone between cells. The total contractile range of the cells (from maximally relaxed to maximally stimulated), however, was independent of baseline stiff-ness. We conclude that HASM cells in culture exhibit a clear, although heterogeneous, response to contractile and relaxing agonists and express the essential mechanical features characteristic of the contractile response observed at the tissue level.