Increased HCN channel driven inward rectification in benign cramp fasciculation syndrome.
Muscle cramps are a common complaint associated with sudden painful involuntary contractions of a muscle. The mechanisms responsible for muscle cramps are still not clear. Axonal excitability and multi-unit electromyography studies were performed in 20 patients suffering from benign cramp fasciculation syndrome, not currently on medication. The measures of axonal excitability suggested greater inward rectification, indicative of an increase in Ih. Mathematical modelling suggested that the data were best explained by depolarization of the voltage dependence of hyperpolarization-activated cyclic nucleotide-gated (HCN) channels. Parameters associated with polarization of resting membrane potential were not changed. These findings suggest that a role for HCN channels may become apparent during the rhythmic discharge associated with a voluntary contraction. Consistent with this view, patients had higher motor unit discharge rates than healthy controls during maximal voluntary effort.
1 Department of Clinical Neurophysiology, Medical School Göttingen, Georg-August-University Göttingen, Robert-Koch-Str. 40, 37075 Göttingen, Germany dirk.czesnik@med.uni-goettingen.de.
Dirk
D
Czesnik
2 The University of Sydney, Sydney, Australia.
James
J
Howells
3 Department of Neurorehabilitation Engineering, Bernstein Focus Neurotechnology Göttingen & Bernstein Center for Computational Neuroscience, Von-Siebold-Str. 6 D - 37075 Göttingen, Germany.
Francesco
F
Negro
1 Department of Clinical Neurophysiology, Medical School Göttingen, Georg-August-University Göttingen, Robert-Koch-Str. 40, 37075 Göttingen, Germany.
Melanie
M
Wagenknecht
1 Department of Clinical Neurophysiology, Medical School Göttingen, Georg-August-University Göttingen, Robert-Koch-Str. 40, 37075 Göttingen, Germany.
Susanne
S
Hanner
3 Department of Neurorehabilitation Engineering, Bernstein Focus Neurotechnology Göttingen & Bernstein Center for Computational Neuroscience, Von-Siebold-Str. 6 D - 37075 Göttingen, Germany.
Dario
D
Farina
2 The University of Sydney, Sydney, Australia.
David
D
Burke
1 Department of Clinical Neurophysiology, Medical School Göttingen, Georg-August-University Göttingen, Robert-Koch-Str. 40, 37075 Göttingen, Germany.
Walter
W
Paulus
D000200:Action Potentials / Q000502:physiology; D000328:Adult; D000368:Aged; D001369:Axons / Q000378:metabolism* / Q000502:physiology; D016022:Case-Control Studies; D004576:Electromyography; D005260:Female; D006801:Humans; D064428:Hyperpolarization-Activated Cyclic Nucleotide-Gated Channels / Q000378:metabolism*; D008297:Male; D008564:Membrane Potentials / Q000502:physiology*; D008875:Middle Aged; D009046:Motor Neurons / Q000378:metabolism*; D009119:Muscle Contraction / Q000502:physiology*; D009120:Muscle Cramp / Q000378:metabolism* / Q000503:physiopathology; D009468:Neuromuscular Diseases / Q000378:metabolism* / Q000503:physiopathology; D055815:Young Adult
D064428:Hyperpolarization-Activated Cyclic Nucleotide-Gated Channels
HCN-channels; Ih; multi-unit EMG; muscle cramps; threshold tracking