Fig. 3

Cl⁻-regulation of ciliary beating in cultured human nasal epithelial cells. Outer dynein arms (ODAs) control the frequency of ciliary movement, and inner dynein arms (IDAs) control waveform including the amplitude (angle) of ciliary movement. Cytosolic Cl⁻ inhibits, respectively, the function of ODAs and IDAs via binding to Cl⁻ biding sites in the axonemal structures of ODAs and IDAs reducing the frequency and the amplitude (angle) of ciliary movement. The sensitivity of ODAs to cytosolic Cl⁻ is less than that of IDA. Cytosolic Cl⁻ at basal levels has no inhibitory effect on ODA function, but inhibits IDA function to some extent, but not completely. When [Cl⁻]_c becomes lower than the basal level, ODA, which is not inhibited by basal levels of Cl⁻, maintains its activity, and IDA, which is partially inhibited by basal levels of Cl⁻, is no longer inhibited by Cl⁻ and its activity is increased. Conversely, as [Cl⁻]_c increases, the activity of both ODA and IDA decreases. This figure is modified from Fig. 8 reported in a study [168] under a Creative Commons Attribution-NonCommercial 4.0 International License