Injection of xKv3.1 antisense RNA into Xenopus embryos reduced delayed rectifier potassium current density by 62% and increased action potential duration from 1.9 ms to 3.5 ms in spinal neurons.
Antisense suppression of xKv3.1 demonstrates its critical role in the maturation of delayed rectifier potassium current and action potential duration in developing spinal neurons.
Absolute Event Rate: 3.5% vs 1.9%
p-value: p=<0.01
A developmental increase in delayed rectifier potassium current (I(Kv)) in embryonic Xenopus spinal neurons is critical for the maturation of excitability and action potential waveform. Identifying potassium channel genes that generate I(Kv) is essential to understanding the mechanisms by which they are controlled. Several Kv genes are upregulated during embryogenesis in parallel with increases in I(Kv) and produce delayed rectifier current when heterologously expressed, indicating that they could encode channels underlying this current. We used antisense (AS) cRNA to test the contribution of xKv3.1 to the maturation of I(Kv), because xKv3.1 AS appears to suppress specifically heterologous expression of potassium current by xKv3.1 mRNA. The injection of xKv3.1 AS into embryos reduces endogenous levels of xKv3.1 mRNA in the developing spinal cord and reduces the amplitude and rate of activation of I(Kv) in 40% of cultured neurons, similar to the percentage of neurons in which endogenous xKv3.1 transcripts are detected. The current in these mature neurons resembles that at an earlier stage of differentiation before the appearance of xKv3.1 mRNA. Furthermore, AS expression increases the duration of the action potential in 40% of the neurons. No change in voltage-dependent calcium current is observed, suggesting that the decrease in I(Kv) is sufficient to account for lengthening of the action potential. Computer-simulated action potentials incorporating observed reductions in amplitude and rate of activation of I(Kv) exhibit an increase in duration similar to that observed experimentally. Thus xKv3.1 contributes to the maturation of I(Kv) in a substantial percentage of these developing spinal neurons.
Vincent et al. (Tue,) reported a other. xKv3.1 antisense (AS) RNA vs. Uninjected cells, nonfluorescent cells, or sense RNA injected cells was evaluated on Delayed rectifier potassium current (IKv) density and action potential duration (p=<0.01). Injection of xKv3.1 antisense RNA into Xenopus embryos reduced delayed rectifier potassium current density by 62% and increased action potential duration from 1.9 ms to 3.5 ms in spinal neurons.