Mechanosensitive and Beta-Adrenergic Control of the Ciliary Beat Frequency of Mammalian Respiratory Tract Cells in Culture

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Abstract
Respiratory tract ciliated cells, obtained from the rabbit trachea and maintained in culture, were sensitive to mechanical stimulation. The mechanical deformation of the cell surface induced a rapid, but transient, increase in ciliary beat frequency. In addition, the beat frequency of these ciliated cells was also increased in a dose-dependent manner by the .beta.-adrenergic drug isoproterenol (10-7 to 10-4 M) and by the calcium ionophore A23187 (10-6 and 10-5 M). To determine if drug and mechanosensitive activation of ciliary beat frequency arise from a common or different cellular mechanism, we investigated the effect of mechanical stimulation on beat frequency in the presence of isoproterenol or A23187. In isoproterenol (10-8 to 10-4 M), none of the parameters used to describe the ciliary beat frequency response to mechanical stimulation was altered. In A23187 (10-6 M or above), the magnitude of the beat frequency response was significantly reduced or almost abolished, suggesting that mechanical stimulation acts, like A23187, to increase ciliary beat frequency by increasing intracellular calcium. Lower concentrations of A23187 had no effect. These results suggest that respiratory tract ciliated cells have at least two independent mechanisms for the control of ciliary beat frequency: one probably utilizing calcium, the other probably cAMP.