2550 S. Mark Duffy et al. Eur. J. Immunol. 2008. 38: 2548–2556 Figure 1. PGE2 closes KCa3.1 in HLMC in a consistent and reversible manner. (A) Current–voltage curve demonstrating suppression of a 1-EBIO-induced KCa3.1 current by 10 5 M PGE2 and partial reversal of the effect following removal of PGE2 (wash). (B) Suppression of KCa3.1 current measured at 140 mV by 10 5 M PGE2 (n 5 22 cells). (C) Shift in whole-cell current reversal potential (Vm) by 10 5 M PGE2 (n 5 22 cells). (D) KCa3.1 current measured at 140 mV after addition of 1-EBIO, suppression by 10 5 M PGE2 and then reversibility of suppression following removal of PGE2 (wash) (n 5 5 cells). (E) Whole-cell current reversal potential (Vm) after the addition of 1-EBIO, a depolarising positive shift in response to 10 5 M PGE2, and then reversibility following removal of PGE2 (wash) (n 5 5 cells). 10 5 M butaprost was also partially reversed by 10 5 M AH6809 (Fig. 3D–F). Current at 140 mV was 58.578.3 pA post butaprost, increasing to 111.6715.9 pA post AH6809 (p 5 0.0004, n 5 12) (Fig. 3E). There was also a signiﬁcant shift in reversal potential (Vm post butaprost 48.175.8 mV, post AH6809 61.073.7 mV, p 5 0.0004) (Fig. 3F). In the presence of & 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim Figure 2. The EP2 receptor agonist butaprost closes KCa3.1 in HLMC. (A) Current–voltage curve demonstrating suppression of a 1-EBIO-induced KCa3.1 current by 10 5 butaprost. (B) Suppression of KCa3.1 current measured at 140 mV by 10 5 M butaprost (n 5 20 cells). (C) Shift in whole-cell current reversal potential (Vm) by 10 5 M butaprost (n 5 20 cells). (D) Concentration–response curves for KCa3.1 suppression by PGE2 and the EP2 agonist butaprost (mean7SEM of ﬁve cells for each). AH6809, PGE2 had no effect on KCa3.1 currents that had been induced by 1-EBIO (current at 140 mV 67.0717.2 pA post 1-EBIO, 66.2715.7 post AH6809, 62.7713.7 pA post PGE2, n 5 7)(Fig. 4A). Similarly, KCa3.1 currents did not appear in resting cells to which AH6809 was added prior to PGE2 (current 6.970.9 pA at baseline, 5.870.6 pA post AH6809, 6.371.1 pA post PGE2, n 5 6) (Fig. 4B). The EP1 and EP3 receptor agonist 17-phenyl trinor PGE2 did not close KCa3.1 after activation with www.eji-journal.eu