Abstract
The equation presented in the previous paper for steady-state membrane ionic current as a function of externally applied electric field strength is numerically analyzed to determine the influence of ionic and membrane molecule parameters on current densities. The model displays selectivity between different ions. A selectivity coefficient Si, defined as the ratio of current carried by an ionic species i at a given field strength to the current carried by a reference species at the same field strength, has the following properties: (a) Si is a function of electric field strength except for ion-membrane molecule interactions yielding velocity independent collision frequencies; (b) for ion-membrane molecule interactions characterized by a collision frequency that is a decreasing (increasing) function of increasing ionic velocity, ions whose Si > 1 (<1) at zero field strength will show maxima (minima) (minima[maxima]) in their Si vs. electric field strength curves.
Full text
PDFSelected References
These references are in PubMed. This may not be the complete list of references from this article.
- Adelman W. J., Jr, Senft J. P. Voltage clamp studies on the effect of internal cesium ion on sodium and potassium currents in the squid giant axon. J Gen Physiol. 1966 Nov;50(2):279–293. doi: 10.1085/jgp.50.2.279. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Binstock L., Lecar H. Ammonium ion currents in the squid giant axon. J Gen Physiol. 1969 Mar;53(3):342–361. doi: 10.1085/jgp.53.3.342. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Chandler W. K., Meves H. Voltage clamp experiments on internally perfused giant axons. J Physiol. 1965 Oct;180(4):788–820. doi: 10.1113/jphysiol.1965.sp007732. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Mackey M. C. Kinetic theory model for ion movement through biological membranes. I. Field-dependent conductances in the presence of solution symmetry. Biophys J. 1971 Jan;11(1):75–90. doi: 10.1016/S0006-3495(71)86196-9. [DOI] [PMC free article] [PubMed] [Google Scholar]