Antisense oligonucleotides targeted to Kir2.1 mRNA significantly reduced whole cell IK1 and specifically knocked down the 21-pS channel in rat ventricular myocytes.
This study demonstrates that the Kir2.1 gene encodes a specific native 21-pS K(+)-channel protein that plays an essential role in the genesis of cardiac IK1.
The cardiac inward rectifying K+ current (IK1) is important in maintaining the maximum diastolic potential. We used antisense oligonucleotides to determine the role of Kir2.1 channel proteins in the genesis of native rat ventricular IK1. A combination of two antisense phosphorothioate oligonucleotides inhibited heterologously expressed Kir2.1 currents in Xenopus oocytes, either when coinjected with Kir2.1 cRNA or when applied in the incubation medium. Specificity was demonstrated by the lack of inhibition of Kir2.2 and Kir2.3 currents in oocytes. In rat ventricular myocytes (4-5 days culture), these oligonucleotides caused a significant reduction of whole cell IK1 (without reducing the transient outward K+ current or the L-type Ca2+ current). Cell-attached patches demonstrated the occurrence of multiple channel events in control myocytes (8, 14, 21, 35, 43, and 80 pS). The 21-pS channel was specifically knocked down in antisense-treated myocytes (fewer patches contained this channel, and its open frequency was reduced). These results demonstrate that the Kir2.1 gene encodes a specific native 21-pS K(+)-channel protein and that this channel has an essential role in the genesis of cardiac IK1.
Nakamura et al. (Sun,) reported a other. Antisense phosphorothioate oligonucleotides targeted to Kir2.1 mRNA vs. Control myocytes was evaluated on Reduction of whole cell IK1 and specific knockdown of the 21-pS channel. Antisense oligonucleotides targeted to Kir2.1 mRNA significantly reduced whole cell IK1 and specifically knocked down the 21-pS channel in rat ventricular myocytes.