Figure 6. 4-AP selectively inhibits the ACh-induced hyperpolarization in the guinea-pig coronary artery.
ACh (10−6 M) was applied for 1 min before (A; Control) and during application of 4-AP (2 × 10−4 M, B; 10−3 M, C), and after washout of 4-AP for 30 min (D). Traces in A-D were recorded from the same cell. In E, the membrane potential (^), and the amplitudes of the slow (▵) and initial (•) hyperpolarizations are shown as a function of the concentration of 4-AP (0 and 10−4–10−3 M). *P < 0.05, compared with control (0 M 4-AP).