Figure 5. SERCA2a/b siRNA reduces [Ca²⁺]_ER content.

(A) Effect of 1 μM TG on the [Ca²⁺]_cyt due to Ca²⁺ release from intracellular stores ([Ca²⁺]_i; ER). The effect of TG was recorded in a Ca²⁺-free HBSS. (●) control; (□) SERCA2a/b siRNA. (B) Histogram showing the amplitude of the TG-induced Ca²⁺ release as an indication of the [Ca²⁺]_ER content, which was estimated by measuring the difference between basal [Ca²⁺]_cyt and the Ca²⁺ peak induced by TG. CTL, control; siRNA, SERCA2a/b siRNA. * Significantly different from the control value (P<0.05). (C) Histogram showing the direct measurement of [Ca²⁺]_ER in response to 100 μM IP₃ as indicated in the Materials and methods section. CTL, control; siRNA, SERCA2a/b siRNA. * Significantly different from the control value (P<0.05).