SD and LrB inhibit Kv1.3 endogenously expressed by Jurkat T cells. (A) Representative traces illustrate that SD inhibited the Kv1.3 current in a Jurkat T cell in a concentration-dependent manner. (B) Bar chart illustrates that 0.0005% and 0.005% SD significantly inhibited the Kv1.3 current density (n = 5, *p < 0.05, **p < 0.01). The inhibitory effect was partially recovered after washout of the drug. (C) Representative current traces show that LrB inhibited Kv1.3 currents in a Jurkat T cell in a concentration-dependent manner and the effect was partially reversible. (D) Concentration-response curve of LrB inhibition of Kv1.3 current in Jurkat T cells. Currents were normalized to the control and fitted by a Hill equation; EC50 value was 19.9 ± 1.8 μM and Hill slope was 1.1 ± 0.1 (n = 8); the structure formula of LrB was shown in the inset.