Systems model predictions for intraciliary Ca2+ concentration and current responses to the transmembrane potential shift. The intraciliary Ca2+ concentrations (A) and Ca2+ currents (B) are calculated according to the model with direct Ca2+-mediated ciliary Ca2+ channels inhibition in response to variable degree of transmembrane potential shift. The responses are colour coded according to the degree of applied transmembrane potential shift. The violet and red coloured lines represent dynamic responses obtained after the smallest and the largest depolarising shift of membrane potential, respectively. The non dimensional membrane potential values following voltage shift from initial ψ0 = -1.2 are shown in (C) and remain the same throughout the figure. The calculations suggest that ciliary membrane depolarisation induces an intraciliary Ca2+ spike over a wide physiological range of depolarising conditions (C, E and G), whereas the current generates a biphasic response (D, F and H). The calculations were carried out for three different levels of parameter α, which reflects the steepness of the Ca2+ channels conductivity dependence on membrane potential.