Assay Method Information

Assay Name:  Electrophysiology Assay
Description:  Blocking of Kir1.1 (ROMK1) currents was examined by whole cell voltage clamp (Hamill et. al. Pfluegers Archives 391:85-100 (1981)) using the IonWorks Quattro automated electrophysiology platform (Molecular Devices, Sunnyvale, Calif.). Chinese hamster ovary cells stably expressing Kir1.1 channels were maintained in T-75 flasks in cell culture media in a humidified 10% CO2 incubator at 37° C. Prior to an experiment, Kir1.1 expression was induced by overnight incubation with 1 mM sodium butyrate. On the day of the experiment, cells were dissociated with 2.5 mL of Versene (Invitrogen 15040-066), a non-enzymatic cell dissociation reagent, for approximately 6 min at 37° C. and suspended in 10 mL of bath solution containing (in mM): 150 NaCl, 10 KCl, 2.7 CaCl2, 0.5 MgCl2, and 5 HEPES, at pH 7.4. After centrifugation, the cell pellet was resuspended in approximately 4.0 mL of bath solution and placed in the IonWorks instrument. The intracellular solution consisted of (in mM): 80 K gluconate, 40 KCl, 20 KF, 3.2 MgCl2, 3 EGTA, and 5 Hepes, at pH 7.4. Electrical access to the cytoplasm was achieved by perforation in 0.13 mg/mL amphotericin B for 4 min. Amphotericin B (Sigma A-4888) was prepared as a 40 mg/mL solution in DMSO.
Affinity data for this assay
 

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