Erlij D, Shen W K, Reinach P, Schoen H
Am J Physiol. 1982 Jul;243(1):C87-95. doi: 10.1152/ajpcell.1982.243.1.C87.
We have examined the effects of dantrolene and D2O on the K+-stimulated respiration in frog skeletal muscle. The threshold for K+ stimulation was around 10 mM extracellular potassium concentration ([K+]o). A further marked increase in respiration to levels about ten times the resting level was noted when [K+]o was between 15 and 20 mM. The increase was sustained for hours when [K+]o was less than 20 mM; however, with higher concentrations the stimulation consisted of an initial burst followed by a decline. Dantrolene shifted the relationship between [K+]o and peak increase in respiration toward higher [K+]o by about 10 mM; in addition it nearly completely blocked the sustained component of the increase. D2O, nearly abolished the K+-induced respiration. Neither agent shifted the relationship between [K+]o and membrane potential nor abolished the stimulation of respiration caused by caffeine. Dantrolene did not block the stimulation of Na+ efflux caused by 15 mM K+. The results with these agents are consistent with the proposal that K+-stimulated respiration is due to Ca2+ release into the cytoplasm. In addition, they provide evidence that the stimulated rate of Ca2+ release into the cytoplasm can remain at a persistently high level for hours provided [K+]o does not exceed 20 mM. We calculated that the level of this constant Ca2+ release is about 3.4 X 10(16) ions/(s.cm3).
我们研究了丹曲林和重水对青蛙骨骼肌中钾离子刺激呼吸的影响。钾离子刺激的阈值约为细胞外钾离子浓度（[K⁺]ₒ）10 mM左右。当[K⁺]ₒ在15至20 mM之间时，呼吸进一步显著增加至约为静息水平的十倍。当[K⁺]ₒ小于20 mM时，这种增加可持续数小时；然而，在更高浓度下，刺激由最初一阵增加随后下降组成。丹曲林使[K⁺]ₒ与呼吸峰值增加之间的关系向更高的[K⁺]ₒ方向移动约10 mM；此外，它几乎完全阻断了增加的持续部分。重水几乎消除了钾离子诱导的呼吸。两种药物都没有改变[K⁺]ₒ与膜电位之间的关系，也没有消除咖啡因引起的呼吸刺激。丹曲林没有阻断15 mM钾离子引起的钠离子外流刺激。这些药物的结果与钾离子刺激呼吸是由于钙离子释放到细胞质中的提议一致。此外，它们提供了证据，即只要[K⁺]ₒ不超过20 mM，钙离子释放到细胞质中的刺激速率可以持续数小时保持在持续高水平。我们计算出这种持续钙离子释放的水平约为3.4×10¹⁶个离子/（秒·立方厘米）。
