Energetics of contraction in phasic and tonic skeletal muscles of the chicken.
Energetics of contraction in phasic and tonic skeletal muscles of the chicken.
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DOI：
10.1085/jgp.62.3.303
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发表时间：
1973-09
期刊：
影响因子：
--
通讯作者：
Schottelius BA
中科院分区：
文献类型：
--
作者：
Rall JA;Schottelius BA
通过测定鸡背阔肌的初始产热，研究了背阔肌的强直前肌（ALD）和相后肌（PLD）的比较能量学。热成分的分析公式为：E = A + W + αF（Δ’L） + f（P, t）。随着肌肉的拉伸，等长抽搐和强直产生的热量呈线性下降。涉及两个过程：一个是张力无关的，激活热，或A；与张力相关的Wi + αF（Δ’L） + f（P, t）。在抽动中，单位张力A在PLD和ALD中是等效的。在PLD中，由于Wi的存在，单位张力的张力相关热量更大；但与张力时间相关的热量f(P, t)，每单位张力，在两个肌肉中是相似的。在强直收缩中，单位张力A和f（P, t）的差异归因于PLD中较大的Vmax。因此，PLD和ALD在等长收缩能量学上的差异可以用张力发展、顺应性、肌球蛋白和网状atp酶活性的内在差异来解释。采用等效张力技术对等张抽动数据进行量化。两块肌肉都表现出与缩短有关的额外热量αF（Δ’L）。在PLD中αF/Pot的比值较大；它与负荷无关，是两个肌肉a/Po值的1 / 2。两种肌肉的焓效率We + Wi/E是相当的。芬恩效应只有在等压能量释放与减少的等距能量消耗基线比较时才能观察到。
Comparative energetics of chicken latissimus dorsi muscles, tonic anterior (ALD) and phasic posterior (PLD), were investigated by measuring initial heat production. Heat components were analyzed in terms of the equation: E = A + W + αF(Δ̄L) + f(P, t) As the muscles were stretched by increments, heat produced in isometric twitches and tetani decreased in a linear fashion. Two processes are involved: one tension independent, the activation heat, or A; and the other tension dependent, Wi + αF(Δ̄L) + f(P, t). In twitches, A, per unit tension, is equivalent in the PLD and ALD. Tension-dependent heat, per unit tension, is greater in the PLD due to Wi; but tension-time-related heat, f(P, t), per unit tension, is similar in both muscles. In tetanic contractions, differences in A and f(P, t), per unit tension, are attributed to the greater Vmax in the PLD. The differences in the energetics of isometric contractions in the PLD and ALD, therefore, can be explained by inherent differences in tension development, compliance, and myosin and reticular ATPase activities. Data from isotonic twitches were quantified by means of the equivalent tension technique. Both muscles exhibited an extra heat associated with shortening, αF(Δ̄L). In the PLD, the ratio αF/Pot is greater; it is load independent and ½ the value of a/Po in both muscles. Enthalpy efficiency, We + Wi/E, is comparable in both muscles. A Fenn effect is observed only when isotonic energy liberation is compared to a decreasing isometric energy expenditure base line.