Analysis of potassium channel functions in mammalian axons by gene knockouts.
Mammalian axons express a rich repertoire of various K channel subtypes whose distribution is profoundly affected by myelination. In the past two decades, functional analysis of axonal K channels has been approached primarily through pharmacology. Recently, gene knockout techniques have been used to specifically delete a particular K channel subtype from axons. This is significant since the bulk of K channels in a myelinated nerve are covered by the myelin, making functional analysis of specific K channel subtypes by traditional means difficult. This review summarizes the first mutational analysis of this sort performed on an axonal fast K channel termed Kv1.1. This K channel is concealed by the myelin loops in the paranodes of all major myelinated fiber tracts, and exhibits highly heterogeneous distribution even in certain non-myelinated CNS axons. Physiological analysis of Kv1.1 null mutants suggest novel functions for this axonal K channel subtype, including modulation of conduction failures at branch points and stabilization of transition zones in myelinated nerves.
Chiu
S Y
SY
Department of Physiology, University of Wisconsin School of Medicine, 1300 University Avenue, 285 Medical Science Building, Madison, WI 53706, USA.
Zhou
L
L
Zhang
C L
CL
Messing
A
A
D000200:Action Potentials / Q000502:physiology; D000818:Animals; D001369:Axons / Q000737:chemistry / Q000502:physiology*; D051379:Mice; D018345:Mice, Knockout / Q000502:physiology*; D015221:Potassium Channels / Q000235:genetics* / Q000378:metabolism
D015221:Potassium Channels