Viral gene transfer of dominant-negative Kv4 construct suppresses an O2-sensitive K+ current in chemoreceptor cells

Abstract

Hypoxia initiates the neurosecretory response of the carotid body (CB) by inhibiting one or more potassium channels in the chemoreceptor cells. Oxygen-sensitive K+ channels were first described in rabbit CB chemoreceptor cells, in which a transient outward K+ current was reported to be reversibly inhibited by hypoxia. Although progress has been made to characterize this current with electrophysiological and pharmacological tools, no attempts have been made to identify which Kv channel proteins are expressed in rabbit CB chemoreceptor cells and to determine +

with adenoviruses that enabled ecdysone-inducible expression of the dominant-negative constructs and reporter genes in poly- cistronic vectors. In voltage-clamp experiments, we found that, whereas adenoviral infections of chemoreceptor cells with Kv1.xDN did not modify the O -sensitive K+ current, infections with Kv4.xDN suppressed the transient outward current in a time-dependent manner, significantly depolarized the cells, and abolished the depolarization induced by hypoxia. Our work dem- onstrate that genes of the Shal K+ channels underlie the tran- +

their contribution to the native O2-sensitive K

current. To probe

sient outward, O2-sensitive, K

current of rabbit CB chemore-

the molecular identity of this current, we have used dominant- negative constructs to block the expression of functional Kv channels of the Shaker (Kv1.xDN) or the Shal (Kv4.xDN) subfam-

ceptor cells and that this current contributes to the cell depolarization in response to low pO2. +

ilies, because members of these two subfamilies contribute to

Key words: O2-sensitive K

current; viral gene transfer;

the transient outward K+ currents in other preparations. Delivery of the constructs into chemoreceptor cells has been achieved