Streaming potential of white matter and gray matter in bovine spinal cord under compressive loading

Abstract

The spinal cord is mainly composed of white matter and gray matter which consist of solid and liquid phases. When the tissue deforms, the liquid phase in the tissue flows out through between the solid phases. The interaction and frictional resistance between the two phases result in the macroscopic visco-elastic behavior. In addition, the solid phase in soft tissue contains a large amount of negatively-charged proteoglycan. This electro chemical behavior affects the visco-elastic properties of the tissue. This study investigated the electro-kinetic behavior of white matter and gray matter under a variety of compressive loadings. Column-shaped specimens, 5 mm diameter and 5 mm height, were made from white matter and gray matter of bovine cervical spinal cord, and the specimens were set in physiological saline. The streaming potential was measured under compressive loading, stress relaxation, and cyclic loading. The results showed the streaming potentials to have a linear relation to tissue stress in compression and relaxation. In cyclic loading tests, the streaming potential changes according to the stress change in the loading. Copyright © 2009 by The Japan Society of Mechanical Engineers.