Figure 6. Inhibitory effect of Rp-8-Br-MB-cAMPS, a membrane-permeant cAMP antagonist, on the STA₂-induced increase in I_sc.

STA₂ (0.3 μm) was added to the serosal side. A, Rp-8-Br-MB-cAMPS (50 μm at the serosal side) was added after the STA₂-elicited plateau phase was observed. A typical trace of I_sc is shown. B, the STA₂-induced net increase in I_sc was recorded just before the addition of Rp-8-Br-MB-cAMPS (filled column). When the effect of the inhibitor reached a steady state, the I_sc values were obtained and expressed as ▵I_sc (hatched column). n = 4. **P < 0.01.