Fig. 3. Directional Ins(1,4,5)P₃ persists regardless of connexin deletion. In the cartoons on the left, the pipette indicates the stimulated cell type (EC top, VSMC bottom), blue represents BAPTA and green represents XPC. In control conditions (A), stimulation of BAPTA-loaded ECs resulted in no increase in [Ca²⁺]_i in either cell type. There was also no increase in [Ca²⁺]_i in either cell type when ECs with Cx43 siRNA that were loaded with BAPTA were stimulated (B), or when Cx40^–/– ECs were loaded with BAPTA and stimulated (C). However, after stimulation of VSMCs loaded with BAPTA in control conditions (D), ECs responded with an increase in [Ca²⁺]_i. When Cx43 siRNA was added to the ECs (E), an increase in EC [Ca²⁺]_i was still observed after VSMC stimulation. When ECs from Cx40^–/– mice were used (F), an increase in EC [Ca²⁺]_i was observed after VSMC stimulation. The addition of XPC to the ECs (G-I) eliminated the increase in EC [Ca²⁺]_i after VSMC stimulation in control conditions (G), when Cx43 siRNA was applied to ECs (H) or when Cx40^–/– ECs were used (I). ^*P<0.05.