Abstract
The activation of potassium ion conductance in squid axons by voltage-clamp depolarization is delayed when the depolarizing step is preceded by a conditioning hyperpolarization of the axonal membrane. Moreover, the control conductance kinetics superpose with the delayed kinetics when they are translated along the time axis by an amount equal to the delay. We have found that the degree of superposition with internally perfused axons depends upon voltage-clamp protocol. The kinetics superpose almost exactly for modest test depolarizations, whereas they clearly fail to superpose completely for more positive levels of membrane depolarization. We have modeled these results by incorporating a time dependence into the rate constant of activation of potassium channel gates in the Hodgkin and Huxley model of potassium ionic conductance.
Full text
PDF
Selected References
These references are in PubMed. This may not be the complete list of references from this article.
- Begenisich T. Conditioning hyperpolarization-induced delays in the potassium channels of myelinated nerve. Biophys J. 1979 Aug;27(2):257–265. doi: 10.1016/S0006-3495(79)85215-7. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Bezanilla F., Armstrong C. M. Negative conductance caused by entry of sodium and cesium ions into the potassium channels of squid axons. J Gen Physiol. 1972 Nov;60(5):588–608. doi: 10.1085/jgp.60.5.588. [DOI] [PMC free article] [PubMed] [Google Scholar]
- COLE K. S., MOORE J. W. Potassium ion current in the squid giant axon: dynamic characteristic. Biophys J. 1960 Sep;1:1–14. doi: 10.1016/s0006-3495(60)86871-3. [DOI] [PMC free article] [PubMed] [Google Scholar]
- French R. J., Wells J. B. Sodium ions as blocking agents and charge carriers in the potassium channel of the squid giant axon. J Gen Physiol. 1977 Dec;70(6):707–724. doi: 10.1085/jgp.70.6.707. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Goldman L., Schauf C. L. Quantitative description of sodium and potassium currents and computed action potentials in Myxicola giant axons. J Gen Physiol. 1973 Mar;61(3):361–384. doi: 10.1085/jgp.61.3.361. [DOI] [PMC free article] [PubMed] [Google Scholar]
- HODGKIN A. L., HUXLEY A. F. A quantitative description of membrane current and its application to conduction and excitation in nerve. J Physiol. 1952 Aug;117(4):500–544. doi: 10.1113/jphysiol.1952.sp004764. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Ilyin V. I., Katina I. E., Lonskii A. V., Makovsky V. S., Polishchuk E. V. The Cole-Moore effect in nodal membrane of the frog Rana ridibunda: evidence for fast and slow potassium channels. J Membr Biol. 1980 Dec 30;57(3):179–193. doi: 10.1007/BF01869586. [DOI] [PubMed] [Google Scholar]
- Palti Y., Ganot G., Stämpfli R. Effect of conditioning potential on potassium current kinetics in the frog node. Biophys J. 1976 Mar;16(3):261–273. doi: 10.1016/S0006-3495(76)85686-X. [DOI] [PMC free article] [PubMed] [Google Scholar]