Figure 4. ARC channel mediated Ca²⁺ entry activates PLCδ3.

A, inclusion of a high concentration of InsP₃ (50 μm) in the pipette solution inhibits the ARC channel-mediated inhibition of Kir2.1 channel currents. Values are means ± SEM. B, representative PCR results showing PLCδ1 RNA levels following expression (100 pmol per siRNA) of a control siRNA (cont), a single siRNA to PLCδ1 (δ1), or combinations of either two different siRNAs to PLCδ1 (2×δ1), or siRNAs to PLCδ1 and PLCδ3 (δ1+δ3). C, representative Western analysis of PLCδ3 protein levels following transfection with a control siRNA, and two different concentrations of the PLCδ3 siRNA, along with β-actin as a loading control. D, effect of expression of various siRNAs (100 pmol per siRNA) on ARC channel induced inhibition of Kir2.1 channel currents. Shown are the mean ± SEM rates of Kir2.1 current inhibition with a control siRNA (cont), with single siRNAs to either PLCδ1, or PLCδ3, two different siRNAs to PLCδ1 (2×δ1), or a combination of siRNAs to PLCδ1 and PLCδ3 (δ1+δ3). E, effect of expression of either an empty vector, or the same vector containing the PLCδ3-H352A mutant construct, on the ARC channel-mediated inhibition of Kir2.1 channel currents. Values are means ± SEM with n shown in parentheses.