cRNA preparations and Xenopus oocyte injection

cRNAs were prepared by first linearizing the DNA plasmid using NheI-HF followed by in vitro RNA transcription using the mMessage mMachine T7 kit (Ambion, Austin, TX). The concentration of cRNA was determined by absorbance at 260 nm. The pGEM-HE vector was used for Xenopus oocyte expression. A total of 50 ng of KCNQ1 cRNA was injected into defolliculated Xenopus laevis oocytes (Ecocyte, Bioscience, Austin, TX) using a Drummond injector (Broomall, PA). Oocytes were incubated at 16°C for ∼36–48 h before recordings.