Sodium channel inactivation defects are associated with acetazolamide-exacerbated hypokalemic periodic paralysis.
A novel mutation in a family with hypokalemic periodic paralysis is described. The mutation R672S is located in the voltage sensor segment S4 of domain II in the SCN4A gene encoding the human skeletal muscle voltage-gated sodium channel. Functional expression of the R672S channels in human embryonic kidney 293 cells revealed a small but significant hyperpolarizing shift in the steady-state fast inactivation, and a dramatic enhancement in channel slow inactivation. These two defects are mainly due to a slow recovery of the mutant channels from fast and/or slow inactivation. Our data may help explain the mechanism underlying hypokalemic periodic paralysis and the patient's worsening from acetazolamide.
Bendahhou
S
S
Howard Hughes Medical Institute, University of Utah, Salt Lake City 84112, USA.
Cummins
T R
TR
Griggs
R C
RC
Fu
Y H
YH
Ptácek
L J
LJ
D000086:Acetazolamide / Q000009:adverse effects*; D000200:Action Potentials / Q000187:drug effects / Q000502:physiology; D000293:Adolescent; D000328:Adult; D002257:Carbonic Anhydrase Inhibitors / Q000009:adverse effects*; D002460:Cell Line; D005260:Female; D006801:Humans; D020514:Hypokalemic Periodic Paralysis / Q000235:genetics / Q000378:metabolism* / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000187:drug effects / Q000502:physiology; D009154:Mutation / Q000235:genetics*; D010375:Pedigree; D026941:Sodium Channel Blockers; D015222:Sodium Channels / Q000235:genetics* / Q000378:metabolism
D002257:Carbonic Anhydrase Inhibitors; D026941:Sodium Channel Blockers; D015222:Sodium Channels; D000086:Acetazolamide