Siess M, Stieler K, Leuchtner J, Delabar U
Basic Res Cardiol. 1986;81 Suppl 1:79-94. doi: 10.1007/978-3-662-11374-5_9.
Special problems of the aerobic metabolism in the cardiac muscle cell as an energy producing and energy consuming system are discussed and demonstrated with some experimental results using superfused resting and working guinea-pig atria as an energetic model: 1. Influence on resting O2 uptake: a) Free fatty acids (FFA) increase the O2 uptake rate to approximately 20% compared with glucose oxidation. This can be explained as a compensating effect due to the 9.7% lower combustion value for 1 mol O2 of C16-FFA and the 10.7% lower P/O-ratio related to glucose oxidation. b) K+-depolarization increases the O2 uptake b.1. between 15 and 65 mmol/l KCl from 110 to 200% without activation of the actomyosin system. This effect is Ca++ dependent and is not observed in Ca++ free solution and can be inhibited completely by nifedipine. The enhanced O2 uptake rate due to K+-depolarization is not connected with an improved state of the energy quotient (ATP/ADP+AMP) indicating a lowering of the energy coupling. b.2. between 100 and 250 mmol/l KCl from 220 to approximately 350%, not influenced by nifedipine and connected with activation of the actomyosin system at low Na+ and/or high external Ca++ (contracture). 2. Stretching of resting atria up to 10 mN tension does not increase the O2 uptake rate. The 'Feng' effect could not be confirmed. 3. a) The 'Frank-Starling' effect can be observed between 2.5 and 10 mN preload with increase of contractile work/beat connected with an enhancement of O2 uptake rate to a lower percentage. At the maximum of the 'Frank-Starling' effect the highest efficiency of contractile work can be observed. With increasing beat rate this maximum is shifted to a lower preload. b) The auxotonic contractile work measured by a calibrated spring blade allows the calculation of the 'internal work' and the 'external contractile work'/beat in mm X mN. The total energy of the activated actomyosin system (total work) is stored by the displacement of the spring blade due to the constant of the spring blade, the preload (tension) and the afterload (force). The 'internal work' will be transformed into ATP dependent heat and force equal to the preload tension. The same ATP dependent energy from O2 uptake is transformed at the same beat rate and the same preload a) with the isometric type of auxotonic contraction into high force and very low internal and low external work.(ABSTRACT TRUNCATED AT 400 WORDS)
本文讨论了心肌细胞作为一个能量产生和消耗系统的有氧代谢的特殊问题，并通过一些实验结果进行了论证。实验以灌注的豚鼠静息和工作心房作为能量模型：1. 对静息氧摄取的影响：a) 与葡萄糖氧化相比，游离脂肪酸（FFA）使氧摄取率提高约20%。这可以解释为一种补偿效应，因为1摩尔C16 - FFA的燃烧值比葡萄糖氧化时低9.7%，且其P/O比值比葡萄糖氧化时低10.7%。b) 钾离子去极化在15至65 mmol/l氯化钾浓度范围内使氧摄取量增加1.5至2.5倍，从110%增至200%，而不激活肌动球蛋白系统。此效应依赖钙离子，在无钙离子溶液中未观察到，且可被硝苯地平完全抑制。钾离子去极化导致的氧摄取率提高与能量商（ATP/ADP + AMP）状态的改善无关，表明能量偶联降低。b.2) 在100至250 mmol/l氯化钾浓度范围内，氧摄取量从220%增至约350%，不受硝苯地平影响，且与低钠和/或高细胞外钙离子（挛缩）时肌动球蛋白系统的激活有关。2. 将静息心房拉伸至10 mN张力不会增加氧摄取率。“冯”效应未得到证实。3. a) 在2.5至10 mN前负荷之间可观察到“弗兰克 - 斯塔林”效应，随着每搏收缩功增加，氧摄取率也增加，但增加百分比更低。在“弗兰克 - 斯塔林”效应最大值时，可观察到收缩功的最高效率。随着心率增加，此最大值会移至更低的前负荷。b) 通过校准的弹簧片测量的辅助等张收缩功可计算出每搏的“内功”和“外部收缩功”，单位为mm×mN。激活的肌动球蛋白系统的总能量（总功）通过弹簧片的位移储存，这取决于弹簧片常数、前负荷（张力）和后负荷（力）。“内功”将转化为依赖ATP的热量和与前负荷张力相等的力。在相同心率和相同前负荷下，来自氧摄取的相同依赖ATP的能量，a) 在辅助等张收缩的等长类型中转化为高力、极低的内功和低外部功。（摘要截断于400字）
