Lännergren J, Noth J
J Gen Physiol. 1973 Feb;61(2):158-75. doi: 10.1085/jgp.61.2.158.
The effect of hypertonic solutions on the tension of isolated twitch muscle fibers of the frog has been investigated. Increased tonicity up to about 1.7 times normal (1.7 T) caused a very small, graded, maintained tension increase. Above about 1.7 T a large, transient contracture response was superimposed on the small tension. The contracture response was graded with tonicity and reached a maximum at 2.5 T of 108 +/- 25 mN.mm(2) a third of the maximum tetanic tension in isotonic solution. Contracture tension developed with a delay which decreased with increased tonicity. The contracture threshold was lower and the delay shorter in small fibers than in large. Contractures were obtained equally well in depolarized as in polarized fibers. They were completely suppressed by 0.1-0.5 mM tetracaine. The possible mechanism responsible for the tension-inducing effect of hypertonic solutions is discussed in terms of the close similarity between the properties of these contractures and those caused by caffeine, and it is suggested that the effect is due to a release of calcium from internal stores.
研究了高渗溶液对青蛙离体单收缩肌纤维张力的影响。张力增加至约正常张力的1.7倍（1.7T）时，会引起非常小的、分级的、持续的张力增加。高于约1.7T时，在小张力之上会叠加一个大的、短暂的挛缩反应。挛缩反应随张力增加而分级，在2.5T时达到最大值，为108±25mN·mm²，是等张溶液中最大强直张力的三分之一。挛缩张力的产生有延迟，且延迟随张力增加而减小。小纤维的挛缩阈值较低，延迟时间比大纤维短。去极化纤维和极化纤维产生挛缩的情况相同。它们被0.1 - 0.5mM的丁卡因完全抑制。根据这些挛缩的特性与咖啡因引起的挛缩特性非常相似，讨论了高渗溶液产生张力诱导作用的可能机制，并提出该作用是由于钙从内部储存库中释放所致。
