Fig. 3.

PKAI inhibits K_V1.3 currents in human T cells. A: downregulation of PKAI abolishes the effect of 8-BrcAMP on K_V1.3 channels in Jurkat cells. K_V1.3 currents were recorded in Jurkat cells after a 48-h transfection with either siPKAI or scr. Representative traces before (black) and after application of 8-BrcAMP (1 mM, gray) are shown in the left panel. Currents were elicited by depolarizing pulses to +50 mV from a HP of −80 mV every 30 s. Average inhibition of K_V1.3 current is shown at right for siPKAI (dark gray, n = 9)- and scr-transfected (light gray, n = 6) and nontransfected Jurkat cells (control, white; n = 6). B: downregulation of PKAII has no influence on the 8-BrcAMP effect on K_V1.3 in Jurkat cells. Left: representative traces before (black) and after 8-BrcAMP (1 mM) application (gray) in siPKAII- and scr-transfected Jurkat cells. Currents were elicited as described in A. Right: average inhibition of K_V1.3 currents in siPKAII (dark gray; n = 7)- and scr-transected cells (light gray; n = 6). C: PKAI inhibits K_V1.3 currents in human primary resting T cells. K_V1.3 currents were recorded in CD3⁺ cells after a 48-h transfection with siPKAI, siPKAII, or scr. Left: representative currents before (black) and after application of 8-BrcAMP (1 mM, gray). Currents were elicited as described in A. Average inhibition of K_V1.3 currents are shown at left for siPKAI (dark gray; n = 8, 3 donors)-, siPKAII (light gray; n = 7, 3 donors)-, and scr-transfected CD3⁺ cells (white; n = 8, 3 donors).