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Journal of Cell Science, Vol 97, 503-508, Copyright © 1990 by Company of Biologists

Submitted on July 3, 1990
Accepted on August 6, 1990

A vibrating electrode analysis of extracellular ion currents in Acetabularia acetabulum

PAUL O'SHEA 1, BRIAN GOODWIN 2, and IRENE RIDGE 2

1 Department of Chemistry and Biological Chemistry, University of Essex, Colchester, UK
2 Department of Biology, The Open University, Milton Keynes MK7 6AA, England, UK

An investigation of extracellular ionic currents in Acetabularia acetabulum is presented. Utilising the vibrating electrode technique it is shown that there are large (up to 380µAcm-2) light-dependent and small (up to 10µAcm-2) light-independent extracellular ionic currents around Acetabularia. The current density was greatest at the rhizoid and diminished towards the developing apex where there was no measurable current.

Ion-replacement and ion-transport inhibitor studies indicated that Cl- was the main constituent of the light-dependent and light-independent currents. Calcium ions were found to contribute about 5-15% of the light-independent current and <1% of the light-dependent current, as deduced from cobalt inhibition studies. Possible mechanisms responsible for these phenomena are discussed briefly.

Key words: extracellular ion currents, development (ionic control), vibrating electrode, Acetabularia acetabulum

Submitted on July 3, 1990
Accepted on August 6, 1990






© The Company of Biologists Ltd 1990