Possible role of apamin-sensitive K+ channels in myotonic dystrophy.

Abstract

Myotonic muscular dystrophy is a genetic disease characterized mainly by muscle atrophy and myotonia, a repetitive electrical activity of muscle. In the present study, the possible role of apamin-sensitive K+ channels in the genesis of myotonia was investigated. Apamin is a peptide from bee venom that specifically blocks small conductance Ca(2+)-activated K+ channels. The injection of a small amount of apamin (20-30 microliters, 10 mumol/L) into the thenar muscle of myotonic dystrophy patients decreased the basal electrical activity during the electromyogram in the 6 patients studied. Myotonic discharges after muscle percussion were more difficult to trigger and of smaller intensity and duration. In 2 controls and in 2 patients with generalized myotonia, as well as in 1 patient with myotonia congenita (where the defect is in chloride channels), apamin had no effect. These results suggest that apamin-sensitive K+ channels participate in the mechanism that generates myotonia in myotonic dystrophy.

• Authors: M I Behrens, P Jalil, A Serani, F Vergara, O Alvarez
• Journal: Muscle & nerve (Muscle Nerve) Vol. 17 Issue 11 Pg. 1264-70 (Nov 1994) ISSN: 0148-639X [Print] United States
• PMID: 7935548 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Potassium Channels
• Apamin

Topics

• Adult
• Apamin (pharmacology)
• Electric Conductivity
• Electromyography
• Electrophysiology
• Female
• Humans
• Male
• Middle Aged
• Myotonic Dystrophy (metabolism)
• Potassium Channels (drug effects, physiology)