Ionic relations of cells of Chara australis. VIII. Membrane currents during a voltage clamp

Findlay, G.P.

Australian J Biol Sci 17(2): 388-399

1964


Accession: 024905467

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Abstract
Experiments are described in which "voltage clamps" were applied to the "membrane" of C. australis cells comprising tonoplast and plasmalemma and also to the plasmalemma alone. The voltage-clamp system maintained the membrane potential at a predetermined level, and enabled a detailed analysis to be made of the transient electrical phenomena occurring during the action potential. A scanning technique is also described, by means of which the membrane current-potential characteristics could be determined at any particular time during the transient activity of the membrane. During a voltage clamp of the potential difference across the plasmalemma, a large transient inward current flowed across that membrane. The concentration of calcium ions in the external medium is shown to play an important role in determining the electrical characteristics of the plasmalemma in its transiently active state.