Figure 6: The Azobenzene-400 core enhances efficiency of potassium channel photopharmacology. See also Figure S6.
(A) Chemical structures (top) of a voltage-gated potassium channel (Kv) pore blocker bearing a quaternary ammonium (orange) and an azobenzene (purple) and schematic (bottom) showing principle of optical control of a Kv channel by AQ or AQ400.
(B-C) Representative HEK 293T whole-cell patch clamp electrophysiology traces showing AQ-mediated (B) or AQ400-mediated (C) photo-blocking of Kv1.1 by 505 nm illumination (green) and photo-unblocking by 385 nm illumination (magenta).
(D) Summary bar graph of efficiency of optical control of Kv1.1 for AQ versus AQ400. *** indicates statistical significance (unpaired t-test, p<0.001). Error bars show s.e.m.
(E-F) AQ400 shows enhanced kinetics of Kv1.1 photo-block as observed in representative whole-cell patch clamp traces (E) and summary bar graphs for channel blocking and unblocking (F). * indicates statistical significance (unpaired t-test, p<0.001 for τBlock and p<0.05 for τUnblock). Data was assessed by analyzing the first ten blocking events per cell. Error bars show s.e.m.
(G-H) AQ400 shows enhanced photocurrents in mouse DRG neurons compared to AQ. Whole-cell patch-clamp traces obtained at −40 mV (G) reveal a larger light-gated current (ΔI (I380nm-I505nm)) for AQ400 (H). * indicates statistical significance (t-test, p<0.05). The numbers of cells tested are shown in parentheses. Error bars show s.e.m.
(I) Representative traces (left) of action potential (AP) firing following 25 pA current injection under illumination with 380 nm (magenta) or 505 nm (green) light in DRG neurons treated with 100 μM AQ400. Right, summary bar graph showing reduced AP firing in 380 nm light in data from n=6 cells. * indicates statistical significance (t-test, p<0.05). Error bars show s.e.m.