The Journal of Membrane Biology

, Volume 18, Issue 1, pp 61–80

The anomalous rectification and cation selectivity of the membrane of a starfish egg cell

  • Susumu Hagiwara
  • Kunitaro Takahashi
Article

DOI: 10.1007/BF01870103

Cite this article as:
Hagiwara, S. & Takahashi, K. J. Membrain Biol. (1974) 18: 61. doi:10.1007/BF01870103

Summary

The cation selectivity and its relation to the inward-going rectification of the immature egg cell membrane of a starfish,Nordora punctiformis, were studied and the following results were obtained. (1) When the external saline contains usual ion species the cell membrane at rest is predominantly permeable to K ions. The K chord conductancegk depends on the electrochemical potential of K ions, ΔV=V−EK′ and the external K concentration [K+]o by
$$g_4 = A\left[ {1 + \exp \left( {\frac{{\Delta V - \Delta V_h }}{\upsilon }} \right)} \right]^{ - 1} ([K^ + ]_0 )^{\tfrac{1}{2}} $$
\((\Delta V_h \underset{\raise0.3em\hbox{$\smash{\scriptscriptstyle\cdot}$}}{ \doteq } - 15mV,\upsilon \underset{\raise0.3em\hbox{$\smash{\scriptscriptstyle\cdot}$}}{ \doteq } 7mV)\). (2) The permeability sequence of monovalent cations and the permeability ratiosPx/PK of the cell membrane at rest obtained with membrane tpotential measurements are, T1 (1.5)>K(1.0)>Rb(0.3 to 0.4)>NH4(0.03 to 0.04)>Na, Cs. (3) Current-voltage relations obtained when the external solution contains Rb+, Cs+ or T1+ in addition to K+ show: (a) Rb+ and Cs+ decrease the K conductance and the rate of decrease becomes greater with an increasing hyperpolarization, thereby the inward-going rectification is reduced; (b) the membrane conductance shows an ‘anomalous mole fraction dependence’ in Tl-K media, i.e., the conductance becomes minimum at a certain mole fraction; and (c) the current-voltage relation often shows a transitiontype behavior suggesting that the membrane undergoes metastable states during an ncrease of hyperpolarization.

Copyright information

© Springer-Verlag New York Inc. 1974

Authors and Affiliations

  • Susumu Hagiwara
    • 1
    • 2
  • Kunitaro Takahashi
    • 1
    • 2
  1. 1.Department of PhysiologyU.C.L.A.Los Angeles
  2. 2.Department of Neurophysiology, Institute of Brain ResearchTokyo University Medical SchoolTokyoJapan

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