Figure 4. Effects of a calmodulin antagonist on the UTP-activated K⁺ current.

Pretreatment of monolayers (10 min) with calmidazolium produced a concentration-dependent inhibition of channel activity. Apical membrane currents were measured using amphotericin B-permeablized monolayers maintained in the presence of 20 nm oestradiol-17β for 4 days. The equation given above (Fig. 3B) was fitted to the data set to derive the following parameters: IC₅₀= 5 ± 0.11 μm; Hill coefficient =−2.0 ± 0.1, n = 5.