Mechanoelectric transduction in bone
- PDF / 1,561,523 Bytes
- 13 Pages / 593.28 x 841.68 pts Page_size
- 19 Downloads / 188 Views
Mechanoelectric transduction in bone Dennis A. Chakkalakal Research Service, VA Medical Center and Department of Orthopaedic Surgery, University of Nebraska Medical Center, Omaha, Nebraska 68105 (Received 3 June 1988; accepted 12 April 1989) The cells in living bone are embedded in a charged, organic-inorganic solid permeated by ionic fluids flowing through a complex network of channels (diameter ~10~ ! -10 2 /am). The solid matrix, which has a high degree of composite material organization beginning at the macromolecular level, has even finer pores of diameter ?slO~3 //,m containing extracellular fluids. Since bone cells are thus bathed in fluid environments of varying ionic composition and concentration, it is likely that the physiology of bone depends on its electrical and electromechanical properties. This hypothesis is supported by the known effects of externally applied mechanical and electrical signals on physiological functions. Contrary to the earlier perception of bone as an insulating material, it is now recognized that the fluid content of bone endows it with physiologically significant conductivity. Mechanoelectric transduction in bone, at low frequencies, is most likely an electrokinetic process associated with the solid-fluid interfaces in bone. Electromechanical properties of bone have been determined experimentally by measurements of stress-generated potentials and streaming potentials in wet bone specimens and electrophoretic mobility of bone particles. Interpretation of results has been difficult due to the complexity of the solid-fluid interfaces in bone and the often undefinable alterations of the pores and interfaces due to specimen preparation. This paper is a review of the present state of knowledge of mechanoelectric transduction in bone and its physiological significance. I. INTRODUCTION The influence of the mechanical properties as well as the structure and composition of bone on its physiological functions has been recognized for a long time. More recently, it has become increasingly evident that the extracellular material of bone is endowed with a variety of other properties which may also subserve some physiological functions of living bone. For example, mechanical stimuli to which bone is subjected during daily activities may influence bone remodeling during growth and in adult life by electrical signals sensed by cells, thereby affecting cell function and bone physiology. Similarly, the observed increase in endogenous electrical activity associated with musculoskeletal injuries may have a physiological role in the healing process. Although these hypotheses have not yet been proven, research during the past three decades has provided much indirect evidence for physiological roles for various material properties of bone. The cells in living bone—osteocytes, osteoblasts, and osteoclasts — are embedded in a porous organic-inorganic material containing a distribution of fixed charges and permeated by ionic fluids flowing through a complex network of channels. In the weight-bearing long bo
Data Loading...
