Double trouble. brain neurons (green) with a defective potassium channel. An EEG and ECG show that seizures ( top ) often coincide with cardiac arrhythmias ( background ) in mice.
A. Goldman et al., Science Translational Medicine
Two medical problems caused by misfiring electrical signals, the epilepsy and cardiac arrhythmia, probably have a common molecular cause, scientists report. Research points to treatments that could reduce the chances of young people dying of crises.
Scientists at the Baylor College of Medicine in Houston, Texas, studied mice that had a mutation in the KCNQ gene, which builds ionic potassium channels that set up a potential action across a cell membrane. These channels help the heart beat after resetting the potential of heart muscle cells contract. The mutation - also found in humans - produces a defective protein that delays the restoration potential, what beats erratic and sometimes death
The ion channel was long thought to work only in heart muscle, but recent work. implies that it works in other tissues. Now Alica Goldman, a neurologist and co-author of the study, discovered the first definitive evidence that the channel has worked in mouse neurons. He was particularly active in brain regions susceptible to crises, the researchers report online this week in Science Translational Medicine . The team also monitored the mutant mice with EEG and ECG machines and determined that seizures often accompany an abnormal heart rhythm. "This is interesting because it provides the first molecular index" that ionic potassium channels underlie epilepsy and arrhythmia, said Jeffrey Noebels, neurologist and senior author of the paper.
Noebels said misfire by cells in the brain or heart could stimulate the release of stress hormones that cause other organs to fail. or aberrant electrical activity in an organ could spread to the other by nerves that connect them. but nailing the exact connections will probably be tricky. in mice, the relationship between seizures and arrhythmia was erratic. It often happened without the other
"the connection is always decoupled in a sense , "says Michael Ackerman, a pediatric cardiologist at the Mayo clinic in Rochester, Minnesota. Ackerman studied epilepsy and severe ion channels, and said the paper is primarily a springboard." the real proof is to return from mice to humans, "he said. This means that the determination of the frequency of mutations in the KCNQ gene cause of epilepsy in humans
Nevertheless, Noebels said the work already points to possible treatments for cases the most severe epilepsy -. 10% of patients, most in their 20s and 30s, likely to die suddenly of convulsions. Previous studies in humans involved in many heart failure before death ( Science , July 4, 08, p. 31). Noebels hope that treatments for defective potassium channels in the heart muscle, such as beta blockers and pacemakers, may, if not prevent crises, at least prevent deaths due to crises. "This is the first time we can say, well, if you have epilepsy, we should examine your heart, too," he said. "And you do not have to wait years to bring to treatment."
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