Ion concentration effects on bone streaming potentials and zeta potentials.

Abstract

Electrical potentials are dependent on the properties of the solid and fluid phases of bone. The solid phase in bone is composed of an organic matrix and inorganic bone mineral fibre, while the fluid phase is separated into compartments associated with the vascular channel system and mineralized matrix. Recently, a piezoelectric and electrokinetic response following mechanical deformation was demonstrated in fully hydrated bone. However, alterations in the fluid phase and the effects on streaming potentials where flow through the sample due to pressure on the fluid phase without prior solid matrix mechanical deformation have not been examined. Streaming potentials in high ionic strength solutions reveal a flow-dependent streaming potential in the absence of mechanical deformation not previously observed in stress-generated potentials. Streaming potentials in high ionic strength sodium chloride solutions (0.75 M) of control and deproteinized samples suggest that organic molecules and ions in the electrical double layer may be susceptible to flow-induced alterations which can modify the streaming potentials generated. Alterations in properties of the fluid phase can modify the streaming and zeta potentials and may play a role in the biofeedback response to bone tissue.