Reaction kinetic parameters for ion transport from steady-state current-voltage curves

• Published in: Biophysical journal Vol. 51; no. 4; pp. 569 - 585
• Main Authors: Gradmann, D., Klieber, H.G., Hansen, U.P.
• Format: Journal Article
• Language: English
• Published: Bethesda, MD Elsevier Inc 01.04.1987; Biophysical Society
• Subjects: Biological and medical sciences; Cell physiology; Electric Conductivity; Fundamental and applied biological sciences. Psychology; Ion Channels - physiology; Kinetics; mathematical models; Mathematics; Membrane and intracellular transports; Models, Biological; Molecular and cellular biology; Potassium - metabolism; Sodium - metabolism; Sodium-Potassium-Exchanging ATPase - metabolism; Ion transport; Ionic channel; Models; Membrane transport; Potassium Ions
• ISSN: 0006-3495; 1542-0086
• DOI: 10.1016/S0006-3495(87)83382-9

This study demonstrates possible ways to estimate the rate constants of reaction kinetic models for ion transport from steady-state current-voltage data as measured at various substrate concentrations. This issue is treated theoretically by algebraic reduction and extension of a reaction kinetic four-state model for uniport. Furthermore, an example for application is given; current-voltage data from an open K+ selective channel (Schroeder, J.I., R. Hedrich, and J.M. Fernandez, 1984, Nature (Lond.), 312:361–362) supplemented by some new data have been evaluated. The analysis yields absolute numerical estimates of the 14 rate constants of a six-state model, which is discussed in a wider context.