K_V3.4 channels are modulated by activation of M₁R but not by activation of Dr-VSP or pseudojanin. (A) Normalized current traces recorded before (black) and during (red) application of 10 µM Oxo-M in a cell transiently transfected with K_V3.4 and M₁R. (B) Same as in A but with expression of Dr-VSP and an activating pulse instead of M₁R. (C) Current traces before (black) and after (red) application of 5 µM rapamycin (rap.) to a cell expressing K_V3.4, pseudojanin-YFP, and LDR-CFP. (D) Representative normalized current traces of cells expressing K_V3.4 recorded under control conditions (black) or after 15-min treatment with 100 nM PMA in Ringer’s solution (red). (E) Fold slowing of inactivation after activation of M₁R, application of 100 nM PMA, or activation of Dr-VSP (n = 4 [M₁R] or 5 [PMA and Dr-VSP]). Error bars represent ±SEM. *, P < 0.05.