In vivo analysis of XXXX function in Xenopus embryonic myocytes.

@entity34118 @entity972
Kv1 @entity972 channels consist of pore-forming alpha subunits as well as auxiliary beta subunits. In heterologous systems, Kv1alpha subunits suffice for induction of voltage-dependent @entity972 current (I(Kv)). Although Kv1 channels can be expressed without auxiliary subunits in heterologous systems, coexpression with Kvbeta subunits has dramatic effects on surface expression and kinetic properties. Much less is known about the functional roles of Kvbeta subunits in vivo, despite their presence in the majority of native Kv1 channel complexes. We used an antisense approach to probe the contribution of @entity34118 subunits to native Kv1 channel function in embryonic myocytes. We compared the effects of antisense @entity34118 treatment on the whole cell I(Kv) to those produced by overexpression of a dominant-negative Kv1alpha subunit. The reductions in the maximal @entity972 conductance produced by antisense @entity34118 treatment and elimination of Kv1alpha subunit function were not significantly different from each other. In addition, simultaneous elimination of Kv1alpha and @entity34118 subunit function resulted in no further reduction of the maximal conductance. The Kv channel complexes targeted by @entity34118 and/or Kv1alpha subunit elimination contributed to action potential repolarization because elimination of either or both subunits led to increases in the duration of the action potential. As for @entity972 conductance, the effects of elimination of both alpha and beta subunits on the duration of the action potential were not additive. Taken together, the results suggest that Kv1 @entity972 channel complexes in vivo have a strong requirement for both alpha and beta subunits.
