Figure 4.
Effects of iberiotoxin on smooth muscle hyperpolarization induced by NS1619, NOR-1 and bradykinin in segments of intact porcine coronary arteries surface in the presence of 1 μM phenylephrine, 300 μM nitro-L-arginine and 10 μM indomethacin. (a) Typical trace in which hyperpolarizations induced by bolus application of increasing concentrations of NOR-1 and bradykinin were compared with those induced by the BKCa channel opener, NS1619 in the absence and presence of iberiotoxin (IbTX). (b) Graphical representation of data from four separate experiments of the types shown in (a) in which each column represents the membrane potential (m.p.),+or−s.e.mean, before and after exposure to bolus doses of NS1619 (330 nmol), NOR-1 (30–300 nmol) or bradykinin (BK; 0.1–1 nmol) calculated to give, transiently, the final bath concentrations indicated. The effects of 100 nM iberiotoxin on the highest concentrations of NS1619 and NOR-1 are also shown.