ELECTRICAL SIGNAL TRANSMISSION IN A BONE CELL NETWORK - THE INFLUENCEOF A DISCRETE GAP JUNCTION

A refined electrical cable model is formulated to investigate the role of a discrete gap junction in the intracellular transmission of elect rical signals in an electrically coupled system of osteocytes and oste oblasts in an osteon. The model also examines the influence of the rat io q between the membrane's electrical time constant and the character istic time of pore fluid pressure, the circular, cylindrical geometry of the osteon, and key simplifying assumptions in our earlier continuo us cable model (see Zhang, D., S. C. Cowin, and S. Weinbaum. Electrica l signal transmission and gap junction regulation in a bone cell netwo rk: A cable model for an osteon. Ann. Biomed. Eng. 25:379-396, 1997). Using this refined model, it is shown that (1) the intracellular poten tial amplitude at the osteoblastic end of the osteonal cable retains t he character of a combination of a low-pass and a high-pass filter as the corner frequency varies in the physiological range; (2) the presen ce of a discrete gap junction near a resting osteoblast can lead to si gnificant modulation of the intracellular potential and current in the osteoblast for measured values of the gap junction coupling strength; and (3) the circular, cylindrical geometry of the osteon is well simu lated by the beam analogy used in Zhang et al. (C) 1998 Biomedical Eng ineering Society.