Lorković H
J Physiol. 1983 Oct;343:569-76. doi: 10.1113/jphysiol.1983.sp014910.
The force of contractures produced by 14-400 mM-K+ (as methanesulphonate) was measured in whole mouse soleus (sol.), extensor digitorum longus (e.d.l.), and in bundles from these muscles. Frog semitendinosus muscles were used for comparison. Whole mouse muscles displayed biphasic contracture responses lasting more than 5 min when provoked by 150m M-K+. Contractures of bundles dissected from these muscles were monophasic and had a short duration. The time required for the muscle bundles to contract and relax to 1/2 maximum force (T) was an inverse function of [K+]. T was increased by lowering [K+] from 400 to 50 mM by a factor of 8.3 and 7.0 in proximal and distal portions of sol. and by a factor of 4.2 and 2.8 in proximal and distal portions of e.d.l., respectively. The force-[K+] relation was steeper for sol. than for e.d.l., and the proximal portions were more sensitive to K+ than the distal portions, particularly in e.d.l. The capability of the muscles to produce force in response to 400 mM-K+ after a 10 min exposure to 30 or 50 mM-K+ was high in sol., somewhat lower in proximal parts of e.d.l. and in frog semitendinosus, and lowest in distal parts of e.d.l. It was concluded that K contractures of mouse muscles are basically monophasic, and that biphasic contractures of whole muscles arise because of K+-diffusion delays, slow responses to intermediate [K+], and differences in responsiveness of the fibres contained in a particular muscle.
测量了14 - 400 mM钾离子（以甲磺酸盐形式）在完整的小鼠比目鱼肌、趾长伸肌以及这些肌肉的肌束中产生的挛缩力。使用青蛙半腱肌作为对照。当受到150 mM钾离子刺激时，完整的小鼠肌肉呈现持续超过5分钟的双相挛缩反应。从这些肌肉中分离出的肌束挛缩是单相的，且持续时间较短。肌肉束收缩和舒张至最大力的1/2所需的时间（T）是[K⁺]的反函数。通过将[K⁺]从400 mM降至50 mM，比目鱼肌近端和远端的T分别增加了8.3倍和7.0倍，趾长伸肌近端和远端的T分别增加了4.2倍和2.8倍。比目鱼肌的力-[K⁺]关系比趾长伸肌更陡峭，且近端部分比远端部分对钾离子更敏感，在趾长伸肌中尤为明显。在暴露于30或50 mM钾离子10分钟后，肌肉对400 mM钾离子产生力的能力在比目鱼肌中较高，在趾长伸肌近端部分和青蛙半腱肌中略低，在趾长伸肌远端部分最低。得出的结论是，小鼠肌肉的钾离子挛缩基本上是单相的，而完整肌肉的双相挛缩是由于钾离子扩散延迟、对中等[K⁺]的缓慢反应以及特定肌肉中所含纤维反应性的差异所致。
