Ionic conductance changes in lobster axon membrane when lanthanum is substituted for calcium.


Journal Article

The trivalent rare earth lanthanum was substituted for calcium in the sea water bathing the exterior of an "artificial node" of a lobster axon in a sucrose gap. It caused a progressive rise in threshold, and a decrease in the height of the action potential as well as in its rates of rise and fall. Prolonged application produced an excitation block. Voltage-clamp studies of the ionic currents showed that the time courses of the ionic conductance changes for both sodium and potassium were increased. Concurrently, the potentials at which the conductance increases occurred were shifted to more positive inside values for the La+++ sea water. These effects resemble changes resulting from a high external calcium concentration. Over and above this, La+++ also causes a marked reduction in the maximum amount of conductance increase following a depolarizing potential step. Membrane action potentials similar to those observed experimentally in the La+++ solution have been computed with appropriate parameter changes in the Hodgkin-Huxley equations.

Full Text

Cited Authors

  • Takata, M; Pickard, WF; Lettvin, JY; Moore, JW

Published Date

  • November 1, 1966

Published In

Volume / Issue

  • 50 / 2

Start / End Page

  • 461 - 471

PubMed ID

  • 11526840

Pubmed Central ID

  • 11526840

International Standard Serial Number (ISSN)

  • 0022-1295

Digital Object Identifier (DOI)

  • 10.1085/jgp.50.2.461


  • eng

Conference Location

  • United States