Kaczmarek Dominik, Łochyński Dawid, Everaert Inge, Pawlak Maciej, Derave Wim, Celichowski Jan
Department of Neurobiology, Poznan University of Physical Education, Poznań, Poland; Department of Physiology, Biochemistry and Hygiene, Poznan University of Physical Education, Poznań, Poland;
Department of Neurobiology, Poznan University of Physical Education, Poznań, Poland; Department of Motor Rehabilitation, Poznan University of Physical Education, Poznań, Poland; and.
J Appl Physiol (1985). 2016 Jul 1;121(1):164-72. doi: 10.1152/japplphysiol.00848.2015. Epub 2016 May 19.
The physiological role of the muscle histidyl dipeptides carnosine and anserine in contractile function of various types of muscle fibers in vivo is poorly understood. Ten adult male Wistar rats were randomly assigned to two groups: control and supplemented for 10 wk with beta-alanine, the precursor of carnosine (∼640 mg·kg body wt(-1)·day(-1)). Thereafter, contractile properties and fatigability of isolated fast fatigable (FF), fast resistant to fatigue (FR), and slow motor units (MUs) from the medial gastrocnemius were determined in deeply anaesthetized animals. The fatigue resistance was tested with a 40-Hz fatigue protocol followed by a second protocol at 40 Hz in fast and 20 Hz in slow units. In the supplemented rats, histidyl dipeptide concentrations significantly increased (P < 0.05) by 25% in the red portion of the gastrocnemius, and carnosine increased by 94% in the white portion. The twitch force of FF units and maximum tetanic force of FR units were significantly increased (P < 0.05), and the half-relaxation time was prolonged in slow units (P < 0.05). FF units showed less fatigue during the first 10 s, and FR units showed higher forces between 10 and 60 s during the 40-Hz fatigue test. In slow units, forces declined less during the first 60 s of the 20-Hz test. In conclusion, this in vivo experiment demonstrates that an elevation in muscle histidyl dipeptide content elicits beneficial changes in MU contractile characteristics and fatigue resistance. Carnosine and anserine seem to play an important yet divergent role in various MUs.
肌肉组织二肽肌肽和鹅肌肽在体内各类肌纤维收缩功能中的生理作用目前还知之甚少。将10只成年雄性Wistar大鼠随机分为两组：对照组和补充组，补充组用肌肽的前体β-丙氨酸进行为期10周的补充（约640毫克·千克体重⁻¹·天⁻¹）。此后，在深度麻醉的动物身上测定了分离自腓肠肌内侧的快速易疲劳（FF）、快速抗疲劳（FR）和慢速运动单位（MU）的收缩特性及疲劳性。采用40赫兹疲劳方案测试疲劳抗性，之后对快速单位以40赫兹、慢速单位以20赫兹进行第二个方案测试。在补充组大鼠中，腓肠肌红色部分的组织二肽浓度显著增加（P<0.05）25%，白色部分的肌肽增加了94%。FF单位的单收缩力和FR单位的最大强直收缩力显著增加（P<0.05），慢速单位的半松弛时间延长（P<0.05）。在40赫兹疲劳测试中，FF单位在前10秒内表现出较少的疲劳，FR单位在10至60秒之间表现出更高的力量。在20赫兹测试的前60秒内，慢速单位的力量下降较少。总之，这项体内实验表明，肌肉组织二肽含量的升高会引起运动单位收缩特性和疲劳抗性的有益变化。肌肽和鹅肌肽似乎在不同的运动单位中发挥着重要但不同的作用。
