Ca2+-dependent regulation of beat frequency of cilia in Paramecium.

Triton-extracted models of Paramecium cells prepared in the presence of Mg2+ and EGTA showed Ca2+ sensitivity not only in the direction of beat but also in the beat frequency of cilia. The beat frequency increased over a range of concentration of Ca2+ from 2 X 10(-7) to 4 X 10(-7) M, in which the model swam forwards. The frequency increased also above 10(-6)M-Ca2+, in which the model swam backwards. The increase in frequency was inhibited by calmodulin antagonists. Intracellular injection of a Ca2+ buffer giving a free Ca2+ concentration of 2 X 10(-7) to 5 X 10(-7) M in intact cells induced an increase in the beat frequency. Therefore, it is very likely that the beat frequency of cilia is regulated by the intracellular concentration of Ca2+.

[1]  H. Machemer,et al.  Frequency and directional responses of cilia to membrane potential changes inParamecium , 1974, Journal of comparative physiology.

[2]  H. Kaneko,et al.  Control of ciliary activities by adenosinetriphosphate and divalent cations in triton-extracted models of Paramecium caudatum. , 1973, The Journal of experimental biology.

[3]  P. Caldwell,et al.  THE DEPENDENCE OF CONTRACTION AND RELAXATION OF MUSCLE FIBRES FROM THE CRAB MAIA SQUINADO ON THE INTERNAL CONCENTRATION OF FREE CALCIUM IONS. , 1964, Biochimica et biophysica acta.

[4]  Y. Naitoh,et al.  Reactivated Triton-Extracted Models of Paramecium: Modification of Ciliary Movement by Calcium Ions , 1972, Science.

[5]  R. Eckert,et al.  Bioelectric control of ciliary activity. , 1972, Science.

[6]  Y. Nakaoka,et al.  Directional change of ciliary beat effected with Mg2+ in Paramecium. , 1979, Journal of cell science.

[7]  F. Oosawa,et al.  Acceleration of Paramecium swimming velocity is effected by various cations. , 1983 .

[8]  A. Means,et al.  Presence and indirect immunofluorescent localization of calmodulin in Paramecium tetraurelia , 1981, The Journal of cell biology.

[9]  L. Nanninga.  The association constant of the complexes of adenosine triphosphate with magnesium, calcium, strontium, and barium ions. , 1961, Biochimica et biophysica acta.

[10]  P Brehm,et al.  An electrophysiological study of the regulation of ciliary beating frequency in Paramecium. , 1978, The Journal of physiology.