Identification of the Ca2+ Conductance Responsible for K+-induced Backward Swimming in Paramecium caudatum

Identification of the Ca2+ Conductance Responsible for K+-induced Backward Swimming in Paramecium... Membrane potential responses of Paramecium caudatum to an application of K+-rich solution were examined to understand the mechanisms underlying K+-induced backward swimming. A wild-type cell impaled by a microelectrode produced action potentials followed by a sustained depolarization in response to an application of a K+-rich test solution. After termination of the application, a prolongation of the depolarization (depolarizing after-potential) took place. Behavioral mutants incapable of exhibiting K+-induced backward swimming did not show depolarizing afterpotentials. Upon short application of K+-rich solution, the timing and duration of the ciliary reversal of the wild-type cell coincided well with the K+-induced depolarization. The duration of the depolarizing afterpotential decreased as the duration of the application increased. The depolarizing afterpotential recovered slowly after it had been suppressed by a preceding application of the K+-rich solution. By injection of an outward current into the wild-type cell, the action potentials were evoked normally during the period when the K+-induced depolarizing afterpotential was suppressed. We concluded that the prolongation of the depolarizing membrane potential response following the application of the K+-rich solution represents the Ca2+ conductance responsible for the K+-induced backward swimming in P. caudatum and that the characteristics of the K+-induced Ca2+ conductance are distinct from those of the Ca2+ conductance responsible for the action potentials. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png The Journal of Membrane Biology Springer Journals

Identification of the Ca2+ Conductance Responsible for K+-induced Backward Swimming in Paramecium caudatum

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Publisher
Springer Journals
Copyright
Copyright © 2002 by Springer-Verlag New York Inc.
Subject
Life Sciences; Biochemistry, general; Human Physiology
ISSN
0022-2631
eISSN
1432-1424
D.O.I.
10.1007/s00232-002-1031-7
Publisher site
See Article on Publisher Site

Abstract

Membrane potential responses of Paramecium caudatum to an application of K+-rich solution were examined to understand the mechanisms underlying K+-induced backward swimming. A wild-type cell impaled by a microelectrode produced action potentials followed by a sustained depolarization in response to an application of a K+-rich test solution. After termination of the application, a prolongation of the depolarization (depolarizing after-potential) took place. Behavioral mutants incapable of exhibiting K+-induced backward swimming did not show depolarizing afterpotentials. Upon short application of K+-rich solution, the timing and duration of the ciliary reversal of the wild-type cell coincided well with the K+-induced depolarization. The duration of the depolarizing afterpotential decreased as the duration of the application increased. The depolarizing afterpotential recovered slowly after it had been suppressed by a preceding application of the K+-rich solution. By injection of an outward current into the wild-type cell, the action potentials were evoked normally during the period when the K+-induced depolarizing afterpotential was suppressed. We concluded that the prolongation of the depolarizing membrane potential response following the application of the K+-rich solution represents the Ca2+ conductance responsible for the K+-induced backward swimming in P. caudatum and that the characteristics of the K+-induced Ca2+ conductance are distinct from those of the Ca2+ conductance responsible for the action potentials.

Journal

The Journal of Membrane BiologySpringer Journals

Published: Dec 1, 2002

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