Changes in the Mechano-Electrochemical Environment in the Extracellular Matrix Surrounding Chondrocytes

2000 ◽  
Author(s):  
V. C. Mow ◽  
X. E. Guo ◽  
D. D. Sun ◽  
W. M. Lai
Keyword(s):  
Extracellular Matrix ◽  
Fluid Flow ◽  
Osmotic Pressure ◽  
Streaming Potential ◽  
Cartilage Explants ◽  
Confined Compression ◽  
Frictional Drag ◽  
Flow Through ◽  
Biomechanical Factors ◽  
And Diffusion

Abstract The objective of this paper is to provide an overall discussion of the biomechanical factors that are required to analyze and interpret data from the explant experiments and to present a description of some of the mechano-electrochemical events in the extracellular matrix (ECM) surrounding chondrocytes occurring within cartilage explants during loading. Five common loading cases of cartilage explants are discussed: hydrostatic pressure, osmotic pressure, permeation, confined compression and unconfined compression. Details of such surface loadings on the internal ECM pressure, fluid and ion flows, deformation and electrical fields are given. Similarities and differences in these quantities due to these five types of loadings are specifically noted. For example, it is noted that there is no practical mechanical loading condition that can be achieved in the laboratory to produce effects that are equal to the effects of osmotic pressure loading within the ECM. Some counter-intuitive effects from these loadings are also described. Further, the significance of flow induced compression of the ECM is emphasized, since this frictional drag effect is likely to be one of the major effects of fluid flow through the porous-permeable ECM. Associated streaming potential and diffusion potential and their dependence on the fixed charge density, are discussed in relation to the fluid flow through the charged ECM and the flow-induced compaction effect. Understanding of the differences among these explant loading cases is important; this can provide clearer understanding of the metabolic responses from chondrocytes in explant loading experiments.

Oscillatory Compressional Behavior of Articular Cartilage and Its Associated Electromechanical Properties

1981 ◽  
Vol 103 (4) ◽  
pp. 280-292 ◽  
Author(s):  
R. C. Lee ◽  
E. H. Frank ◽  
A. J. Grodzinsky ◽  
D. K. Roylance
Keyword(s):  
Fluid Flow ◽  
Articular Cartilage ◽  
Molecular Mechanisms ◽  
Fluid Velocity ◽  
Streaming Potential ◽  
Usual Sense ◽  
Frequency Range ◽  
Confined Compression ◽  
Streaming Potentials ◽  
Compressive Stiffness

The compressive stiffness of articular cartilage was examined in oscillatory confined compression over a wide frequency range including high frequencies relevant to impact loading. Nonlinear behavior was found when the imposed sinusoidal compression amplitude exceeded a threshold value that depended on frequency. Linear behavior was attained only by suitable control of the compression amplitude. This was enabled by real time Fourier analysis of data which provided an accurate assessment of the extent of nonlinearity. For linear viscoelastic behavior, a stiffness could be defined in the usual sense. The dependence of the stiffness on ionic strength and proteoglycan content showed that electrostatic forces between matrix charge groups contribute significantly to cartilage’s compressive stiffness over the 0.001 to 20 Hz frequency range. Sinusoidal streaming potentials were also generated by oscillatory compression. A theory relating the streaming potential field to the fluid velocity field is derived and used to interpret the data. The observed magnitude of the streaming potential suggests that interstitial fluid flow is significant to cartilage behavior over the entire frequency range. The use of simultaneous streaming potential and stiffness data with an appropriate theory appears to be an important tool for assessing the relative contribution of fluid flow, intrinsic matrix viscoelasticity, or other molecular mechanisms to energy dissipation in cartilage. This method is applicable in general to hydrated, charged polymers.

scholarly journals Indicator Dispersal by Convection and Diffusion in Fluid Flow Through a Tube

1965 ◽  
Vol 17 (3) ◽  
pp. 274-277 ◽  
Author(s):  
DAVID C. RICH ◽  
JOHN W. GOODMAN
Keyword(s):  
Fluid Flow ◽  
Flow Through ◽  
And Diffusion

Oscillatory Fluid Flow Through a Porous Medium Channel Bounded by Two Impermeable Parallel Plates

1991 ◽  
Vol 113 (3) ◽  
pp. 509-511 ◽  
Author(s):  
J. M. Khodadadi
Keyword(s):  
Porous Medium ◽  
Fluid Flow ◽  
Symmetry Plane ◽  
Velocity Profiles ◽  
Net Energy ◽  
Phase Lag ◽  
High Porosity ◽  
Parallel Plates ◽  
Frictional Drag ◽  
Flow Through

In the absence of the inertia effects, the analytic solution to the fully developed oscillatory fluid flow through a porous medium channel bounded by two impermeable parallel plates is presented. For the limiting case when a highly viscous fluid undergoes slow pulsation in a high porosity medium, the phase lag vanishes and similar velocity profiles are observed. At the other extreme limiting situation, fluid flow near the symmetry plane has a phase lag of 90 deg from the pressure gradient wave. Moreover, the velocity profiles exhibit maxima next to the wall which is similar to the “channeling” phenomenon observed in variable-porosity studies. It is shown that the temporal average of the frictional drag over a period vanishes, indicating no net energy losses due to oscillations.

On the Electric Potentials Inside a Charged Soft Hydrated Biological Tissue: Streaming Potential Versus Diffusion Potential

2000 ◽  
Vol 122 (4) ◽  
pp. 336-346 ◽  
Author(s):  
W. Michael Lai ◽  
Van C. Mow ◽  
Daniel D. Sun ◽  
Gerard A. Ateshian
Keyword(s):  
Fluid Flow ◽  
Articular Cartilage ◽  
Electric Potential ◽  
Compressive Strain ◽  
Streaming Potential ◽  
Potential Effect ◽  
Diffusion Potential ◽  
Confined Compression ◽  
Interstitial Fluid Flow ◽  
One Dimensional

The main objective of this study is to determine the nature of electric fields inside articular cartilage while accounting for the effects of both streaming potential and diffusion potential. Specifically, we solve two tissue mechano-electrochemical problems using the triphasic theories developed by Lai et al. (1991, ASME J. Biomech Eng., 113, pp. 245–258) and Gu et al. (1998, ASME J. Biomech. Eng., 120, pp. 169–180) (1) the steady one-dimensional permeation problem; and (2) the transient one-dimensional ramped-displacement, confined-compression, stress-relaxation problem (both in an open circuit condition) so as to be able to calculate the compressive strain, the electric potential, and the fixed charged density (FCD) inside cartilage. Our calculations show that in these two technically important problems, the diffusion potential effects compete against the flow-induced kinetic effects (streaming potential) for dominance of the electric potential inside the tissue. For softer tissues of similar FCD (i.e., lower aggregate modulus), the diffusion potential effects are enhanced when the tissue is being compressed (i.e., increasing its FCD in a nonuniform manner) either by direct compression or by drag-induced compaction; indeed, the diffusion potential effect may dominate over the streaming potential effect. The polarity of the electric potential field is in the same direction of interstitial fluid flow when streaming potential dominates, and in the opposite direction of fluid flow when diffusion potential dominates. For physiologically realistic articular cartilage material parameters, the polarity of electric potential across the tissue on the outside (surface to surface) may be opposite to the polarity across the tissue on the inside (surface to surface). Since the electromechanical signals that chodrocytes perceive in situ are the stresses, strains, pressures and the electric field generated inside the extracellular matrix when the tissue is deformed, the results from this study offer new challenges for the understanding of possible mechanisms that control chondrocyte biosyntheses. [S0148-0731(00)00604-X]

Fluid Flow Through a Porous Medium Channel With Permeable Walls

1992 ◽  
Vol 114 (1) ◽  
pp. 124-126 ◽  
Author(s):  
J. M. Khodadadi ◽  
J. T. Kroll
Keyword(s):  
Porous Medium ◽  
Fluid Flow ◽  
Shape Parameter ◽  
Theoretical Study ◽  
Maximum Velocity ◽  
Momentum Equation ◽  
Frictional Drag ◽  
Inertia Effects ◽  
Permeable Walls ◽  
Flow Through

A theoretical study of the fully developed fluid flow through a porous medium channel bounded by two permeable walls is presented. In the absence of inertia effects, a closed-form analytic solution to the volume-averaged momentum equation is obtained. The velocity profiles are illustrated for several combinations of the porous medium shape parameter and the blowing Reynolds number. The variations of the maximum velocity and the boundary frictional drag coefficient are also discussed.

STABILITY OF COUPLE STRESS FLUID FLOW THROUGH A HORIZONTAL POROUS LAYER

2016 ◽  
Vol 19 (5) ◽  
pp. 391-404 ◽  
Author(s):  
B. M. Shankar ◽  
I. S. Shivakumara ◽  
Chiu-On Ng
Keyword(s):  
Fluid Flow ◽  
Porous Layer ◽  
Couple Stress ◽  
Couple Stress Fluid ◽  
Flow Through
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