Fig. 9.
TPA inhibits the potassium current induced by irreversible activation of the G-protein. A, The sustained current (measured as Ihold at −40 mV; see legend of Fig. 5B) as a function of time after perfusion with TPA (50 nm) or with the inactive phorbol ester 4α-PMA (50 nm). Perfusion of TPA or 4α-PMA (indicated by bars) is started directly after repetitive FMRFa applications. TPA (left) causes a rapid decrease of the sustained current compared with the decrease under control conditions, i.e., with 4α-PMA (right).B, Average reduction of the sustained current after 4 min of perfusion of TPA (56 ± 8%; n = 5) or control medium with inactive phorbol ester 4α-PMA or DMSO (33 ± 7%; n = 8). *p < 0.05; unpaired t test.