The electrical environment of chondrocytes in normal and OA cartilage: streaming potential VS nernst potential

摘要

Cellular metabolic activities are regulated by both genetic and environmental factors. For chondrocytes, it has been demonstrated that these factors include deformations, fluid shear stresses, hydrostatic and osmotic pressures and electricalpotentials and currents [e.g., Schneiderman et al, 1986; Sah et al, 1989; Hall et al, 1991; Urban et al, 1993; Guilak et al. 1994, Kim et al, 1995]. For many years, it has been known that the high fixed charge density (FCD) of the proteoglycans inarticular cartilage (AC) plays important roles in governing tissue hydration, swelling pressure, load support and the kinetics of fluid and ion transport through the tissue. In situ, chondrocytes, residing in the extracellular matrix (ECM) are surroundedby these charges, and their associated mobile ions. When the tissue deforms, its FCD changes, causing changes to the local electrical environment around the chondrocytes. This may be the basis for the electric signals that chondrocytes see in situ.Therefore, the aim of this study is to determine how this mechano-electrochemical signal transduction process occurs within the ECM of normal and OA articular cartilage. In this study, we wish to test our hypothesis that softening of the tissue during OA[Armstrong and Mow, 1982] and loss of proteoglycan from the ECM [Maroudas, 1979] not only can affect the magnitude of the electrical potential surrounding chondrocytes, but also can reverse the polarity of the electric field.