Figure 2.

Illustration of the acute effect of IL-1β on the 40 pS K⁺ channel in RPTECs. IL-1β activates phospholipase C (PLC), which generates diacylglycerol (DAG) and 1,4,5-trisphosphate (IP₃) from phosphatidylinositol 4,5-bisphosphate (PIP₂) in the cytoplasmic membrane. Binding of IP₃ to the IP₃ receptor of the intracellular Ca²⁺ sore releases Ca²⁺. Both the DAG and increased intracellular Ca²⁺ activate PKC, which consequently phosphorylates the channel and/or its related proteins, suppressing the channel activity. IL-1R: IL-1 receptor.