title: Ca2+-dependent regulation of beat frequency of cilia in Paramecium.
abstract: 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+.
mesh_terms: D000255:Adenosine Triphosphate / Q000494:pharmacology; D000818:Animals; D002118:Calcium / Q000494:pharmacology; D002147:Calmodulin / Q000037:antagonists & inhibitors; D002923:Cilia / Q000187:drug effects / Q000502:physiology; D004305:Dose-Response Relationship, Drug; D009068:Movement / Q000187:drug effects; D010247:Paramecium / Q000502:physiology* / Q000648:ultrastructure; D013449:Sulfonamides / Q000494:pharmacology; D013997:Time Factors
chemical_list: D002147:Calmodulin; D013449:Sulfonamides; C017967:W 7; D000255:Adenosine Triphosphate; D002118:Calcium