Analysis of Bulk-Diffusion-Limited Exchange of Ions in Smooth Muscle Preparations

Abstract

Smooth muscle cells are embedded in a matrix of extracellular connective tissue and intervening water. In many preparations, this can account for half or more of the tissue volume. Therefore, studies which attempt to define isotope kinetics of smooth muscle per se have the added difficulty of determining the modifications imposed by movement of tracer through the extracellular space. There is also the related problem of defining flux components whose exchange with the external solution may be entirely limited by diffusion through the extracellular matrix. These problems are not unique to smooth muscle research, as evidenced by earlier approaches to diffusion—skeletal muscle ion exchange properties (Harris and Burn, 1949; Keynes, 1954).