Effects of Spadin on the TREK-1 channel activity. A-B) Whole-cell currents measured in COS-7 transfected cells in presence of potassium blockers (K⁺ blockers, 10 mM tetraethyl ammonium (TEA), 3 mM 4-aminopyridine (4-AP), 50 nM charybdotoxin, 10 μM glibenclamide, 100 nM apamin). Cells are clamped at -80 mV and voltage changes are applied by ramp from -100 to 50 mV, 1 s in duration Currents are recorded after TREK-1 activation by 10 μM arachidonic acid (aa) and aa + Spadin (100 nM) (A) or aa + propeptide (PE, 500 nM) (B). Native currents are recorded in the absence (Control) and in the presence of spadin or PE. C) Dose-dependent spadin inhibition of TREK-1 currents, IC₅₀ value at 0 mV is of 70.7 nM. Currents are measured in the presence of 10 μM aa. D, Native currents recorded in the presence of K⁺ blockers after stimulation by 10 μM of aa on CA3 pyramidal neurons from hippocampus slices in wild-type mice (D) or in kcnk2 deficient mice (TREK-1 KO) (Inset) in the presence or the absence of spadin (1 μM). Currents are elicited by a ramp from –100 mV to 50 mV.