This is the readme.txt for the model associated with the paper
Chiesa N, Rosati B, Arcangeli A, Olivotto M, Wanke E. A novel role
for HERG K+ channels: spike-frequency adaptation. J Physiol 1997;501:313-318
1. The regular firing of a Hodgkin-Huxley neurone endowed with fast Na+
and delayed K+ channels can be converted into adapting firing by appending
HERG (human eag-related gene) channels. 2. The computer model predictions
were verified by studying the firing properties of F-11 DRG neurone x
neuroblastoma hybrid cells induced to differentiate by long- term exposure
to retinoic acid. These cells, which express HERG currents (IHERG), show
clear spike-frequency adaptation of their firing when current clamped with
long depolarizations. 3. In agreement with the prediction, the selective
blocking of IHERG by class III antiarrhythmic drugs always led to the
disappearance of the spike- frequency adaptation, and the conversion of
adapting firing to regular firing. 4. It is proposed that, in addition to their
role in the repolarization of the heart action potential, HERG channels may
sustain a process of spike-frequency adaptation, and hence contribute to the
control of burst duration in a way that is similar to that of the K+ currents,
IAHP, IC and IM. In addition to the known cardiac arrhythmia syndrome
(LQT2), genetic mutations or an altered HERG expression could lead to
continuous hyperexcitable states sustained by the inability of nerve or endocrine
cells to accommodate to repetitive stimuli. This might help in clarifying the
pathogenesis of still undefined idiopathic familial epilepsies.
To run the models:
XPP: start with the command
Mouse click on Initialconds, and then (G)o.
This makes a trace similar to fig 1E of the paper.
Regarding xpp program, please contact with
Bard Ermentrout's website http://www.pitt.edu/~phase/
describes how to get and use xpp (Bard wrote xpp).
These model files were submitted by:
Dr. Sheng-Nan Wu
Natl Cheng Kung U Med Coll
Tainan 70101, Taiwan