Figure 5. UCL 1848 blocks rSK3 and the AHP with similar potency but exhibits a marked selectivity for rSK2.

A, the effect of 10 nm UCL 1848 on SK3 current recorded from a stably transfected CHO cell. Block was maximal after 3 min exposure to UCL 1848 and the current recovered after 4 min washout. B, inhibition of the AHP by 2 nm UCL 1848. The superimposed traces show the mean of 3 action potentials and AHPs recorded from a rat SCG neurone before (control), at the end of a 70 s application of 2 nm UCL 1848 and 4 min after washout when recovery was almost complete. The resting membrane potential of the cell was -59 mV. C, concentration-inhibition curves for inhibition by UCL 1848 of rSK2 current (▵), rSK3 current (□) and the AHP (○). Each point is the mean of 3-5 observations and vertical bars indicate the s.e.m. Continuous lines are best fits of the Hill equation to the data and the IC₅₀ values have been included in Table 1.