Intracellular calcium oscillations regulate ciliary beat frequency of airway epithelial cells.
The effect of ATP-induced Ca2+ oscillations on ciliary activity was examined in airway epithelial cells by simultaneously measuring the ciliary beat frequency (CBF) and the intracellular Ca2+ concentration ([Ca2+]i) near the base of the cilia. Exposure to extracellular ATP (ATPo) induces a rapid and large increase in both [Ca2+]i and CBF, followed by oscillations in [Ca2+]i and a sustained elevation in CBF. After each Ca2+ oscillation, the [Ca2+]i returned to near basal values. By contrast, the CBF remained elevated during these Ca2+ oscillations, although each Ca2+ oscillation induced small variations in CBF. During Ca2+ oscillations, increases in CBF closely followed the rising phase of increases in [Ca2+]i, but declines in CBF lagged behind declines in [Ca2+]i. Higher frequency Ca2+ oscillations reduced variations in CBF, producing a stable and sustained elevation in CBF. The maximal CBF was induced by Ca2+ oscillations and was 15% greater than the CBF induced by the substantially larger initial [Ca2+]i increase. These data demonstrate that the rate of CBF is not directly dependent on the absolute [Ca2+]i, but is dependent on the differential changes in [Ca2+]i and suggest that CBF in airway epithelial cells is regulated by frequency-modulated Ca2+ signaling.
Evans
J H
JH
Department of Physiology, University of Massachusetts Medical School, Worcester 01655, USA.
Sanderson
M J
MJ
D000255:Adenosine Triphosphate / Q000494:pharmacology; D000818:Animals; D002118:Calcium / Q000378:metabolism; D020013:Calcium Signaling / Q000187:drug effects / Q000502:physiology*; D002478:Cells, Cultured; D002923:Cilia / Q000187:drug effects / Q000502:physiology; D004847:Epithelial Cells / Q000187:drug effects / Q000378:metabolism* / Q000502:physiology*; D007424:Intracellular Fluid / Q000378:metabolism* / Q000502:physiology; D011817:Rabbits; D013997:Time Factors; D014132:Trachea / Q000187:drug effects / Q000502:physiology*
D000255:Adenosine Triphosphate; D002118:Calcium