Relationship between force and Ca2+ concentration in smooth muscle as revealed by measurements on single cells.
Relationship between force and Ca2+ concentration in smooth muscle as revealed by measurements on single cells.
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通过对单细胞的测量揭示了平滑肌中力和 Ca2 浓度之间的关系。
DOI：
10.1073/pnas.85.11.4109
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发表时间：
1988
影响因子：
11.1
通讯作者：
Fay,FS
中科院分区：
文献类型：
--
作者：
Yagi,S;Becker,PL;Fay,FS
通过同时测量单个平滑肌细胞中的等长力和[Ca2+]，研究了Ca2+在调节平滑肌收缩中的作用。 [Ca2+] 使用 fura-2 和高时间分辨率双波长数字微荧光计测量，力使用连接到探针的超灵敏力传感器测量，探针绑在细胞的一端。在最大电刺激后，[Ca2+] 和力都会增加，其中 [Ca2+] 在第一次可检测到的力增加之前显着增加。力的发展表现出对 150 至 500 nM Ca2+ 之间的 [Ca2+] 的最大敏感性。这种 Ca2+ 敏感性可以解释许多生理刺激产生完全收缩的事实，即使这些刺激仅将 Ca2+ 增加到 600-800 nM。当Ca2+被诱导快速增加时，[Ca2+]与力之间的关系表现出滞后性。在收缩开始期间，给定 [Ca2+] 下的力低于肌肉恢复休息期间的力，因此表明平滑肌中存在连接 Ca2+ 和力发展的缓慢步骤。这种滞后的方向在收缩期间发生逆转，其中 Ca2+ 缓慢增加，表明收缩过程随着时间的推移对 [Ca2+] 变得不敏感。完整的单个平滑肌细胞中钙与力之间的关系在许多方面不同于先前在平滑肌的化学透化多细胞制剂中发现的关系。
The role of Ca2+ in regulating smooth muscle contraction was investigated by measuring isometric force and [Ca2+] simultaneously in individual single smooth-muscle cells. [Ca2+] was measured with fura-2 and a high time-resolution dual-wavelength digital microfluorimeter, and force was measured with an ultrasensitive force transducer attached to a probe around which was tied one end of the cell. Both [Ca2+] and force increase after maximal electrical stimulus, with [Ca2+] increasing considerably before the first detectable increase in force. Force development exhibited maximal sensitivity to [Ca2+] between 150 and 500 nM Ca2+. This Ca2+ sensitivity can account for the fact that many physiological stimuli produce full contraction even though such stimuli only increase Ca2+ to 600-800 nM. When Ca2+ was induced to increase rapidly, the relation between [Ca2+] and force exhibited hysteresis. During the onset of contraction, force at a given [Ca2+] was lower than during the muscle's return to rest, thus suggesting the existence of a slow step(s) linking Ca2+ and force development in smooth muscle. The direction of this hysteresis reversed during contractions in which Ca2+ increased slowly, suggesting that the contractile process becomes desensitized to [Ca2+] with time. These relations between calcium and force in intact single smooth-muscle cells differ in many respects from the relation found previously in chemically permeabilized multicellular preparations of smooth muscle.