Figure 5

IP ₃ R3 silencing changed the characteristics of ATP-induced Ca²⁺ signalling in MCF-7 cells. (A) Typical ATP-induced Ca²⁺ signals in MCF-7 cells 72 h after their transfection with siC (a) or siR3 (b). ATP (5 μM) was perfused in a Ca²⁺-free recording solution in order to avoid Ca²⁺ entry. The Ca²⁺ response changed from a plateau-type pattern to a characteristic oscillatory pattern in siR3-transfected cells. Representative for 6 independent experiments. (B) Statistical analysis of the effect of IP₃R3 silencing at 24, 48 and 72 h post-transfection on the percentage of oscillating cells in response to 5 μM ATP in a Ca²⁺-free recording solution. IP₃R3 gene silencing resulted, at any time, in a strong augmentation of the percentage of cells that respond to ATP by an oscillatory Ca²⁺ signal. (C) Typical ATP-induced Ca²⁺ signals recorded in a Ca²⁺-free medium 72 h after transfection with siC (a) or siR3 (b). Ca²⁺ signals presented in a (full line) and b (dotted line) were superimposed in order to clearly show the modification of the pattern of the Ca²⁺ response (c).