Inhibitory action of high formamide concentrations on excitation‐contraction coupling in skeletal muscle
Inhibitory action of high formamide concentrations on excitation‐contraction coupling in skeletal muscle
复制标题
高浓度甲酰胺对骨骼肌兴奋收缩耦合的抑制作用
DOI：
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发表时间：
1982
影响因子：
4.2
通讯作者：
J. D. Del Castillo
中科院分区：
文献类型：
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作者：
G. E. de Motta;F. Códoba;M. de León;J. D. Del Castillo
当浸泡在含有0.4-0.9 M甲酰胺（FMD）的Krebs-Ringer溶液中时，豚鼠回肠条丧失超过70%的收缩力。这种效应不会伴随着组织水分的明显损失，并且通过在正常溶液中洗涤制剂可以完全逆转。青蛙缝匠肌也麻痹时，浸泡在林格氏液含有口蹄疫，但更高的浓度（1.0-2.0 M）和更长的曝光时间是必需的。将这些肌肉转移到正常林格氏肌后，收缩力不会恢复。然而，收缩蛋白仍然对钙激活剂作出反应，这一事实表明，这些肌肉在咖啡因存在下仍然收缩。FMD解偶联的肌肉膜保留电兴奋性，神经肌肉传递似乎未受损。然而，尖峰的早期后电位的改变表明发生了肌管破坏。因此，FMD似乎对肌肉产生两种单独的影响：收缩性的可逆抑制，如在回肠条中观察到的，以及由于当青蛙肌肉恢复正常林格氏液时观察到的渗透压休克而导致的不可逆阻断。可逆效应可能与干扰激活剂钙的可用性有关，因为在FMD处理的亚细胞组分中未观察到对肌动球蛋白样和钙依赖性和非依赖性ATP酶活性的显著抑制作用。
Strips of guinea pig ileum lose over 70% of their contractility when bathed in Krebs‐Ringer solution containing 0.4–0.9 M formamide (FMD). This effect is not accompanied by an appreciable loss of tissue water and is totally reversed by washing the preparation in normal solution. Frog sartorius muscles also paralyze when immersed in Ringer containing FMD, but higher concentrations (1.0–2.0 M) and longer exposure times are required. Contractility is not recovered upon transferring these muscles to normal Ringer. However, the contractile proteins still respond to activator calcium as shown by the fact that these muscles still contract in the presence of caffeine. The membrane of muscles uncoupled by FMD retain electrical excitability, and neuromuscular transmission appears to be unimpaired. However, alterations in the early after‐potential of the spikes suggest the occurrence of a sarcotubular disruption. Therefore, FMD appears to exert two separate effects on muscle: a reversible inhibition of contractility, as observed in ileal strips and an irreversible blockade due to an osmotic shock observed when frog muscles are returned to normal Ringer. The reversible effect is probably related to interference with the availability of activator calcium, since no marked inhibitory effects on the activities of the actomyosin‐like and the calcium‐dependent and ‐independent ATPases could be observed on FMD‐treated subcellular fractions.