title: A High-Throughput Electrophysiology Assay Identifies Inhibitors of the Inwardly Rectifying Potassium Channel Kir7.1.
abstract: Kir7.1 is an inwardly rectifying potassium channel that has been implicated in controlling the resting membrane potential of the myometrium. Abnormal uterine activity in pregnancy plays an important role in postpartum hemorrhage, and novel therapies for this condition may lie in manipulation of membrane potential. This work presents an assay development and screening strategy for identifying novel inhibitors of Kir7.1. A cell-based automated patch-clamp electrophysiology assay was developed using the IonWorks Quattro (Molecular Devices, Sunnyvale, CA) system, and the iterative optimization is described. In total, 7087 compounds were tested, with a hit rate (>40% inhibition) of 3.09%. During screening, average Z' values of 0.63 ± 0.09 were observed. After chemistry triage, lead compounds were resynthesized and activity confirmed by IC50 determinations. The most potent compound identified (MRT00200769) gave rise to an IC50 of 1.3 µM at Kir7.1. Compounds were assessed for selectivity using the inwardly rectifying potassium channel Kir1.1 (ROMK) and hERG (human Ether-à-go-go Related Gene). Pharmacological characterization of known Kir7.1 inhibitors was also carried out and analogues of VU590 tested to assess selectivity at Kir7.1.
authors: MRC Technology, Center for Therapeutics Discovery, London, UK paul.wright@tech.mrc.ac.uk.
authors: Paul D
authors: PD
authors: Wright
authors: Essen BioScience Ltd, Welwyn Garden City, Hertfordshire, UK.
authors: Srinivasan
authors: S
authors: Kanumilli
authors: MRC Technology, Center for Therapeutics Discovery, London, UK.
authors: David
authors: D
authors: Tickle
authors: MRC Technology, Center for Therapeutics Discovery, London, UK.
authors: Jamie
authors: J
authors: Cartland
authors: MRC Technology, Center for Therapeutics Discovery, London, UK.
authors: Nathalie
authors: N
authors: Bouloc
authors: Essen BioScience Ltd, Welwyn Garden City, Hertfordshire, UK.
authors: Timothy
authors: T
authors: Dale
authors: Essen BioScience Ltd, Welwyn Garden City, Hertfordshire, UK.
authors: Derek J
authors: DJ
authors: Tresize
authors: Division of Reproductive Health, Warwick Medical School, Clinical Sciences Research Laboratory, Coventry, UK.
authors: Conor
authors: C
authors: McCloskey
authors: Division of Reproductive Health, Warwick Medical School, Clinical Sciences Research Laboratory, Coventry, UK.
authors: Samantha
authors: S
authors: McCavera
authors: Division of Reproductive Health, Warwick Medical School, Clinical Sciences Research Laboratory, Coventry, UK.
authors: Andrew M
authors: AM
authors: Blanks
authors: MRC Technology, Center for Therapeutics Discovery, London, UK.
authors: Catherine
authors: C
authors: Kettleborough
authors: MRC Technology, Center for Therapeutics Discovery, London, UK.
authors: Jeffrey C
authors: JC
authors: Jerman
mesh_terms: D000818:Animals; D057205:Automation, Laboratory; D016466:CHO Cells; D003412:Cricetulus; D055808:Drug Discovery / Q000379:methods*; D055724:Electrophysiological Phenomena / Q000187:drug effects; D057166:High-Throughput Screening Assays; D006801:Humans; D018408:Patch-Clamp Techniques; D026902:Potassium Channel Blockers / Q000494:pharmacology*; D024661:Potassium Channels, Inwardly Rectifying / Q000037:antagonists & inhibitors* / Q000378:metabolism*; D015203:Reproducibility of Results
chemical_list: C489477:Kir7.1 channel; D026902:Potassium Channel Blockers; D024661:Potassium Channels, Inwardly Rectifying
keywords: Kir; ion channels; pharmacology; potassium channels; screening