Analysis of Transient Swelling and Electrical Responses of an Isolated Cell to Sudden Osmotic Loading

Abstract

Abstract The cell volume changes in response to changes in the osmolality of an extracellular medium. When the medium osmolality decreases, extracellular water will move into the cell so that the cell volume increases (swelling). The rate of change in cell volume depends on the material properties of the cell, such as the tensile stiffness and hydraulic permeability. During cell swelling, the cell membrane is stretched, possibly affecting membrane permeability to various ions (i.e., stretch-activated ion-channels). The transport of ions and water will result in a change in membrane potential [e.g., 1] as well as a change in intracellular ion concentrations. Therefore, mechanical, chemical and electrical events are coupled within a cell. It is important to understand these coupled events in order to separate mechanical and chemical signals and to begin to elucidate the biophysical signal transduction pathways. As a first step to model a cell, we have begun to study mechanical, chemical and electrical phenomena across a cell membrane using recently developed theories [1–3]. In this study, we report our analysis of transient swelling and electrical responses of an isolated cell to an osmotic load, which has been studied experimentally [e.g., 4]. The objective of this study was to relate the changes in cell volume, intracellular ion concentration and electrical potential (which can be readily measured) to the cell material properties (e.g., stiffness, hydraulic permeability and ion-channels).