Fig. 9.

Genistein fails to attenuate PMA suppression of K⁺ currents. A: control preparation exposed to 100 nM PMA showed reductions in I_A and I_Delayed measured about 20 min following PMA exposure (top traces: currents before PMA; bottom traces: currents ∼20 min after PMA exposure). B: summary data depicting PMA's suppression of K⁺ currents, for 4 cells, measured 20 min after bath application of PMA. Both the transient (I_A) and sustained (I_Delayed) components of K⁺ current were decreased. The voltage dependence of I_A and I_Delayed was unaffected by PMA. C: genistein-treated preparation exposed to 100 nM PMA also showed reductions in I_A and I_Delayed measured about 20 min following PMA exposure (top traces: currents before PMA; bottom traces: currents about 20 min after PMA exposure). D: summary data depicting PMA's suppression of K⁺ currents for cells treated first with genistein, measured 20 min after bath application of PMA. For genistein-treated preparations, the reductions of I_A and I_Delayed by PMA were comparable to those observed in cells that had not been exposed to genistein (compare with B). Prior to PMA exposure, however, the K⁺ currents were larger for the genistein-treated cells (compare with A). The voltage dependence of I_A and I_Delayed was not significantly affected by PMA in the presence of genistein.