Figure 4. Competition for CFTR pore... | Rockefeller University Press

$Figure 4. Competition for CFTR pore block between NPPB, 3NB, and 3PP. (A–F) Responses of decaying macroscopic locked-open K1250A CFTR currents, recorded at membrane potentials of −80 (A, C, and E) or 60 mV (B, D, and F), to brief exposures to the following drug combinations: (A and B) 32 mM 3NB (blue bars) and/or 210 µM NPPB (brown bars), (C and D) 20 mM 3PP (red bars) and/or 210 µM NPPB (brown bars), and (E and F) 32 mM 3NB (blue bars) and/or 20 mM 3PP (red bars). Zero-current levels (dotted lines) were estimated from the responses of final current segments to application of either 32 mM 3NB or 210 µM NPPB. (G and H) Fractional currents, normalized to control (gray bars), recorded at −80 mV (G) or 60 mV (H) membrane potentials in the presence of 210 µM NPPB (brown bars), 32 mM 3NB (blue bars), 20 mM 3PP (red bars), or their combinations (striped bars, same color coding). Horizontal lines illustrate fractional currents predicted for mixtures (see Materials and methods), assuming either completely independent (yellow lines) or mutually exclusive (green lines) binding of the two drugs in the pore. Mean ± SEM is shown.$

Figure 4.

Competition for CFTR pore block between NPPB, 3NB, and 3PP. (A–F) Responses of decaying macroscopic locked-open K1250A CFTR currents, recorded at membrane potentials of −80 (A, C, and E) or 60 mV (B, D, and F), to brief exposures to the following drug combinations: (A and B) 32 mM 3NB (blue bars) and/or 210 µM NPPB (brown bars), (C and D) 20 mM 3PP (red bars) and/or 210 µM NPPB (brown bars), and (E and F) 32 mM 3NB (blue bars) and/or 20 mM 3PP (red bars). Zero-current levels (dotted lines) were estimated from the responses of final current segments to application of either 32 mM 3NB or 210 µM NPPB. (G and H) Fractional currents, normalized to control (gray bars), recorded at −80 mV (G) or 60 mV (H) membrane potentials in the presence of 210 µM NPPB (brown bars), 32 mM 3NB (blue bars), 20 mM 3PP (red bars), or their combinations (striped bars, same color coding). Horizontal lines illustrate fractional currents predicted for mixtures (see Materials and methods), assuming either completely independent (yellow lines) or mutually exclusive (green lines) binding of the two drugs in the pore. Mean ± SEM is shown.

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