Impedance of the amphibian lens

The Journal of Physiology
G DuncanP B Pynsent

Abstract

1. The electrical resistance of the perfused frog lens was measured using separate internal current passing and voltage measuring electrodes. 2. The resistance values obtained using voltage clamp and direct and alternating current techniques were in good agreement. 3. The voltage transients induced in response to current steps were multi-exponential in form. Increasing the external K concentration reduced both the amplitude of the voltage response and the rise time. 4. The impedance characteristics were investigated in more detail using alternating current analysis techniques. 5. In an equivalent-circuit modelling study it was assumed that there were two major pathways for current flow in the lens. The first through the surface membranes and the second through the inner fibre membranes via the narrow extracellular spaces. 6. The experimental impedance loci could not be adequately fitted by a simple two time constant model and a third time constant was introduced which may represent diffusion polarization effects in the extracellular spaces. 7. The three time constant model gave good and consistent fits to impedance data from a number of preparations. 8. The form of the impedance loci was also dependent on the external K concent...Continue Reading

Citations

Jun 1, 1988·The Journal of Membrane Biology·G DuncanR M Warn
May 9, 2008·Experimental Eye Research·Catherine ChengXiaohua Gong
Nov 1, 1982·Experimental Eye Research·J L RaeR S Eisenberg
Oct 1, 1981·Experimental Eye Research·T J Jacob, G Duncan
Jun 1, 1990·Current Eye Research·S A GandolfiG Maraini
Apr 1, 1985·Current Eye Research·R T Mathias, J L Rae
Jul 28, 2010·American Journal of Physiology. Regulatory, Integrative and Comparative Physiology·Jeremy D RhodesJulie Sanderson
May 1, 1990·The American Journal of Physiology·J M WolosinO A Candia
Sep 4, 2003·Journal of Cell Science·Valery I Shestopalov, Steven Bassnett

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