Biomaterial Database

CARRIER MODEL FOR ACTIVE TRANSPORT OF IONS ACROSS A MOSAIC MEMBRANE. 1964

A FINKELSTEIN

The central purpose of this paper is to elucidate in a well defined system the meaning of certain phenomena and concepts associated with the active transport of ions. To this end a specific model for a carrier system which actively transports a single ionic species is analyzed and discussed in detail. It is assumed in this model that the carrier-mediated ionic transport occurs in regions of the membrane physically separate from those regions in which free ionic movement takes place,-coupling between the active and passive regions of the membrane occurring through local current flows. The model is seen to display the following characteristics: (a) Starting from identical solutions on the two sides of the membrane, there is produced a redistribution of ions; (b) with identical solutions on the two sides of the membrane there exists a potential difference across the membrane, i.e., the "pump" is electrogenic; (c) the "short circuit" current for symmetrical solutions is equal to the flux of the neutral ion carrier complex; (d) the rate of active transport (and hence of metabolism) is dependent on the ionic concentrations in the surrounding solutions. Throughout the paper comparison is made between features of the model and properties displayed by biological active transport systems, but there is no claim of an identity between the two.

UI	MeSH Term	Description	Entries
D007474	Ion Exchange	Reversible chemical reaction between a solid, often one of the ION EXCHANGE RESINS, and a fluid whereby ions may be exchanged from one substance to another. This technique is used in water purification, in research, and in industry.	Exchange, Ion
D007477	Ions	An atom or group of atoms that have a positive or negative electric charge due to a gain (negative charge) or loss (positive charge) of one or more electrons. Atoms with a positive charge are known as CATIONS; those with a negative charge are ANIONS.
D008566	Membranes	Thin layers of tissue which cover parts of the body, separate adjacent cavities, or connect adjacent structures.	Membrane Tissue,Membrane,Membrane Tissues,Tissue, Membrane,Tissues, Membrane
D008962	Models, Theoretical	Theoretical representations that simulate the behavior or activity of systems, processes, or phenomena. They include the use of mathematical equations, computers, and other electronic equipment.	Experimental Model,Experimental Models,Mathematical Model,Model, Experimental,Models (Theoretical),Models, Experimental,Models, Theoretic,Theoretical Study,Mathematical Models,Model (Theoretical),Model, Mathematical,Model, Theoretical,Models, Mathematical,Studies, Theoretical,Study, Theoretical,Theoretical Model,Theoretical Models,Theoretical Studies
D010827	Physiology	The biological science concerned with the life-supporting properties, functions, and processes of living organisms or their parts.
D012106	Research	Critical and exhaustive investigation or experimentation, having for its aim the discovery of new facts and their correct interpretation, the revision of accepted conclusions, theories, or laws in the light of newly discovered facts, or the practical application of such new or revised conclusions, theories, or laws. (Webster, 3d ed)	Research Priorities,Laboratory Research,Research Activities,Research and Development,Activities, Research,Activity, Research,Development and Research,Priorities, Research,Priority, Research,Research Activity,Research Priority,Research, Laboratory
D002463	Cell Membrane Permeability	A quality of cell membranes which permits the passage of solvents and solutes into and out of cells.	Permeability, Cell Membrane
D006863	Hydrogen-Ion Concentration	The normality of a solution with respect to HYDROGEN ions; H+. It is related to acidity measurements in most cases by pH	pH,Concentration, Hydrogen-Ion,Concentrations, Hydrogen-Ion,Hydrogen Ion Concentration,Hydrogen-Ion Concentrations
D001692	Biological Transport	The movement of materials (including biochemical substances and drugs) through a biological system at the cellular level. The transport can be across cell membranes and epithelial layers. It also can occur within intracellular compartments and extracellular compartments.	Transport, Biological,Biologic Transport,Transport, Biologic
D001693	Biological Transport, Active	The movement of materials across cell membranes and epithelial layers against an electrochemical gradient, requiring the expenditure of metabolic energy.	Active Transport,Uphill Transport,Active Biological Transport,Biologic Transport, Active,Transport, Active Biological,Active Biologic Transport,Transport, Active,Transport, Active Biologic,Transport, Uphill