PARVALBUMIN CONTENT AND CA2+ AND MG2+ DISSOCIATION RATES CORRELATED WITH CHANGES IN RELAXATION RATE OF FROG-MUSCLE FIBERS
PARVALBUMIN CONTENT AND CA2+ AND MG2+ DISSOCIATION RATES CORRELATED WITH CHANGES IN RELAXATION RATE OF FROG-MUSCLE FIBERS
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DOI：
10.1113/jphysiol.1991.sp018752
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发表时间：
1991-09-01
影响因子：
5.5
通讯作者：
RALL, JA
中科院分区：
文献类型：
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作者：
HOU, TT;JOHNSON, JD;RALL, JA
1. 进行实验是为了检验小清蛋白 (PA) 促进青蛙骨骼肌松弛的假设。 使用来自林蛙骨骼肌的单纤维和纯化的 PA 来确定 PA 浓度 ([PA])、PA 中的 Ca2+ 和 Mg2+ 解离率以及作为破伤风持续时间函数的 0 摄氏度下松弛率变化之间的关系。2。 胫骨前肌纤维中的总 [PA] 为 0.76 +/- 0.20 mmol PA l-1 肌浆水（平均值 +/- S.D.，n = 25），其中 65% PA IVa 和 35% PA IVb，其中 PA IVa 和 PA IVb 是 PA 亚型。3。 等长破伤风的松弛率随着破伤风持续时间的变化而逐渐减慢，呈指数时间过程，速率常数为 1.18 +/- 0.35 s-1 (n = 17)。 长期破伤风后松弛率恢复的时间过程呈指数关系，速率常数为 0.12 +/- 0.02 s-1 (n = 14).4。 长期破伤风后松弛率的恢复程度与纤维中的总[PA]相关（相关系数(r) = 0.80，n = 7；P < 0.05）。5。 纯化 PA 中 Mg2+ 和 Ca2+ 的解离速率常数分别为 0.93 +/- 0.02 s-1 (n = 5) 和 0.19 +/- 0.01 s-1 (n = 5)。 PA 亚型 IVa 和 IVb 的解离速率常数没有显着差异。 这些速率常数类似于分别为弛豫速率减慢和恢复的时间过程确定的速率常数。6． 结果表明，弛豫率减慢和恢复的时间过程在很大程度上可以分别通过 PA 中 Mg2+ 和 Ca2+ 解离来控制。 该证据支持 PA 在 0 摄氏度破伤风期间促进青蛙骨骼肌松弛的作用。
1. Experiments were done to test the hypothesis that parvalbumin (PA) promotes relaxation in frog skeletal muscle. Single fibres and purified PA from Rana temporaria skeletal muscle were used to determine the relationship between PA concentration ([PA]), Ca2+ and Mg2+ dissociation rates from PA and changes in rate of relaxation as a function of tetanus duration at 0-degrees-C.2. Total [PA] in fibres from tibialis anterior muscles is 0.76 +/- 0.20 mmol PA l-1 myoplasmic water (mean +/- S.D., n = 25) with 65% PA IVa and 35% PA IVb, where PA IVa and PA IVb are PA isoforms.3. Relaxation rate from an isometric tetanus slows progressively as a function of tetanus duration with an exponential time course and a rate constant of 1.18 +/- 0.35 s-1 (n = 17). Time course of recovery of relaxation rate after a prolonged tetanus is exponential with a rate constant of 0.12 +/- 0.02 s-1 (n = 14).4. The extent of recovery of relaxation rate after a prolonged tetanus was correlated with total [PA] in fibres (correlation coefficient (r) = 0.80, n = 7; P < 0.05).5. Dissociation rate constants for Mg2+ and Ca2+ from purified PA are 0.93 +/- 0.02 s-1 (n = 5) and 0.19 +/- 0.01 s-1 (n = 5), respectively. Dissociation rate constants were not significantly different for PA isoforms IVa and IVb. These rate constants are similar to the rate constants determined for the time courses of slowing and recovery of relaxation rate, respectively.6. Results suggest that the time courses of slowing and recovery of relaxation rate may be controlled, to a large extent, by Mg2+ and Ca2+ dissociation from PA, respectively. This evidence supports a role for PA in facilitating relaxation during a tetanus in frog skeletal muscle at 0-degrees-C.