Applied Physiology and Nutrition Research Group, School of Physical Education and Sport; Rheumatology Division; Faculdade de Medicina FMUSP, Universidade de Sao Paulo, Sao Paulo, SP, Brazil.
Rheumatology Division; Faculdade de Medicina FMUSP, Universidade de Sao Paulo, Sao Paulo, SP, Brazil.
Sci Rep. 2020 Mar 17;10(1):4908. doi: 10.1038/s41598-020-61587-x.
Carnosine is a dipeptide abundantly found in human skeletal muscle, cardiac muscle and neuronal cells having numerous properties that confers performance enhancing effects, as well as a wide-range of potential therapeutic applications. A reliable and valid method for tissue carnosine quantification is crucial for advancing the knowledge on biological processes involved with carnosine metabolism. In this regard, proton magnetic resonance spectroscopy (1H-MRS) has been used as a non-invasive alternative to quantify carnosine in human skeletal muscle. However, carnosine quantification by 1H-MRS has some potential limitations that warrant a thorough experimental examination of its validity. The present investigation examined the reliability, accuracy and sensitivity for the determination of muscle carnosine in humans using in vitro and in vivo experiments and comparing it to reference method for carnosine quantification (high-performance liquid chromatography - HPLC). We used in vitro 1H-MRS to verify signal linearity and possible noise sources. Carnosine was determined in the m. gastrocnemius by 1H-MRS and HPLC to compare signal quality and convergent validity. 1H-MRS showed adequate discriminant validity, but limited reliability and poor agreement with a reference method. Low signal amplitude, low signal-to-noise ratio, and voxel repositioning are major sources of error.
肌肽是一种二肽，在人体骨骼肌、心肌和神经元细胞中含量丰富，具有多种赋予增强性能的特性，以及广泛的潜在治疗应用。一种可靠和有效的组织肌肽定量方法对于推进与肌肽代谢相关的生物学过程的知识至关重要。在这方面，质子磁共振波谱（1H-MRS）已被用作定量人体骨骼肌中肌肽的非侵入性替代方法。然而，1H-MRS 定量肌肽存在一些潜在的局限性，需要对其有效性进行彻底的实验检验。本研究通过体外和体内实验，检查了使用 1H-MRS 确定人体肌肉肌肽的可靠性、准确性和灵敏度，并将其与肌肽定量的参考方法（高效液相色谱 - HPLC）进行了比较。我们使用体外 1H-MRS 来验证信号的线性和可能的噪声源。通过 1H-MRS 和 HPLC 来确定比目鱼肌中的肌肽，以比较信号质量和收敛有效性。1H-MRS 显示出足够的判别有效性，但可靠性有限，与参考方法的一致性也较差。低信号幅度、低信噪比和体素重新定位是主要的误差源。
