Oscillations in ciliary beat frequency and intracellular calcium concentration in rabbit tracheal epithelial cells induced by ATP
Department of Physiology
Adenosine Triphosphate; Animals; Buffers; Calcium; Cells, Cultured; Chelating Agents; Cilia; Egtazic Acid; Hydrolysis; Intracellular Membranes; Oscillometry; Osmolar Concentration; Rabbits; Respiratory Mucosa; Time Factors; Trachea
Life Sciences | Medicine and Health Sciences
To investigate how Ca(2+) regulates airway ciliary activity, changes in ciliary beat frequency (CBF) and intracellular calcium concentration ([Ca(2+)](i)) of rabbit tracheal ciliated cells, in response to ATP, were simultaneously quantified with high-speed phase-contrast and fast fluorescence imaging. [ATP] 1 but < 16 microM induced a similar increase in [Ca(2+)](i) and CBF but this was followed by oscillations in CBF and [Ca(2+)](i). The minimum CBF of the oscillations in CBF remained elevated above the basal rate while the minimum concentration of the [Ca(2+)](i) oscillations returned to the basal level. The minimum and maximum CBF of the oscillations in CBF were independent of the [ATP], whereas the frequency of the oscillations in CBF was dependent on the [ATP]. Similar oscillations in CBF and [Ca(2+)](i) were induced by ATP- gamma -S. Although ADP, AMP and adenosine induced a Ca(2+)-independent increase in CBF, neither ATP nor ATP- gamma -S induced an increase in CBF when the Ca(2+) increases were abolished by 20 microM BAPTA AM, a result suggesting that ATP hydrolysis was minimal. [ATP] >or=16 microM induced a sustained elevation in CBF and only a temporary, non-oscillating increase in [Ca(2+)](i). A similar response was induced by thapsigargin (2 microM). Flash photolysis of caged Ca(2+) (NP-EGTA) produced both transient and prolonged increases in [Ca(2+)](i) which were accompanied by transient and sustained increases in CBF, respectively. From these results, we propose that CBF can be increased by a direct Ca(2+) -dependent mechanism that generates the rapid increases in CBF associated with the oscillations or by an indirect Ca(2+)-dependent mechanism that is responsible for the sustained minimum increase in CBF.
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Citation: J Physiol. 2003 Feb 1;546(Pt 3):733-49.
The Journal of physiology acetoxymethyl ester)
Zhang, Luo and Sanderson, Michael J., "Oscillations in ciliary beat frequency and intracellular calcium concentration in rabbit tracheal epithelial cells induced by ATP" (2003). Open Access Articles. 1485.