Features of the dynamics of the optical and physiological properties of muscle tissue in vitro during its compression

Background and Objectives: The compression of human skin is one of the mechanisms of mechanical biotissue optical clearing. In this study we investigated the effects of compression of in vitro cow muscle tissue samples on diffuse reflectance spectra of tissue and changes of its physiological properties. The purpose of research was to identify the correlation between diffuse reflectance of muscle tissue and its compression. Material and Methods: Samples of muscle tissue used in the experiments with a size of 70–50 mm and a thickness of 25 mm were cut from one volume of the loin hart of a cow. After applying pressure to the sample for a time of about 20 minutes, reflectance spectra of the samples were recorded with a time step of 5 seconds. In the experiments, sensors of different sizes were varied with different values of the applied external compression. Results: The dynamics of myoglobin and hemoglobin content in muscle tissue ex vivo in the compression process was determined. In the case of muscle tissue ex vivo, the blood content in it decreases when compression is applied. A similar effect was observed for skin tissue in vivo, but there are also significant differences: if for skin tissue capillary blood, and hemoglobin, when a pressure of about 105 Pa is applied, is completely removed from biological tissue, then myoglobin from muscle tissue samples is not completely removed, the oxygenated form of myoglobin turns into deoxygenated and deoxygenation of myoglobin occurs within a few minutes after the application of compression. Conclusion: In perspective compression of muscle tissue ex vivo can become the basis for a method for controlling the content of hemoglobin and myoglobin derivatives and, as a result, for controlling the color of biological tissue.