The duration of ciliary reversal of Paramecium caudatum in response to changes in external ionic factors was determined with various ionic compositions of both equilibration and stimulation media. The reversal response was found to occur when calcium ions bound by an inferred cellular cation exchange system were liberated in exchange for externally applied cations other than calcium. Factors which affect the duration of the response were (a) initial amount of calcium bound by the cation exchange system, (b) final amount of calcium bound by the system after equilibration with the stimulation medium, and (c) concentration of calcium ions in the stimulation medium. An empirical equation is presented which relates the duration of the response to these three factors. On the basis of these and previously published data, the following hypothesis is proposed for the mechanism underlying ciliary reversal in response to cationic stimulation: Ca++ liberated from the cellular cation exchange system activates a contractile system which is energized by ATP. Contraction of this component results in the reversal of effective beat direction of cilia by a mechanism not yet understood. The duration of reversal in live paramecia is related to the time course of bound calcium release.
Article| January 01 1968
Ionic Control of the Reversal Response of Cilia in Paramecium caudatum : A calcium hypothesis
From the Zoological Institute, Faculty of Science, University of Tokyo, Tokyo, Japan.
Dr. Naitoh's present address is the Department of Zoology, Syracuse University, Syracuse, New York 13210, and the Marine Biological Laboratory, Woods Hole, Massachusetts 02543
Received: May 08 1967
Online Issn: 1540-7748
Print Issn: 0022-1295
Copyright © 1968 by The Rockefeller University Press
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Yutaka Naitoh; Ionic Control of the Reversal Response of Cilia in Paramecium caudatum : A calcium hypothesis . J Gen Physiol 1 January 1968; 51 (1): 85–103. doi: https://doi.org/10.1085/jgp.51.1.85
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