Fig. 5.

Gβγ inhibition prevents activation of Kv7.4 channels by exogenous PIP₂. A Representative inside-out patch recording showing stimulatory action of PIP₂. Subpanels b and c are 1.75-s segments of channel openings in the absence (b) and presence of PIP₂ (100 μM, c) taken from long-term recording (a). Closed state and multiple open states are denoted by C and O1–O3. B Mean concentration-effect for PIP₂ (n = 4–11). C Representative inside-out patch recording showing that in the continued presence of 50 μM M201 (continuation of recording from patch shown in Fig. 4D), 100 μM PIP₂ applied to the patch failed to activate the channels. Subpanel b is a 1.5-s segment of channel openings taken from long-term recording (a). Closed state and multiple open states are denoted by C and O1. D Representative inside-out patch recording showing that in the continued presence of 100 μM gallein, 100 μM PIP₂ applied to the patch failed to activate the channels. Subpanel b is a 2.5-s segment of channel openings taken from long-term recording (a). E Representative inside-out patch recording showing that in the continued presence of 100 μM Grk2i (continuation of recording from patch shown in Fig. 4E), 100 μM PIP₂ applied to the patch produced only negligible activation of the channels. Subpanel b is a 2.8-s segment of channel openings taken from long-term recording (a). F Normalized increase in NPo produced by 100 μM PIP₂ applied to inside-out patches in the absence and presence of different Gβγ inhibitors (n = 4–6)