AJP - Cell Physiology, Vol 260, Issue 6 C1347-C1351, Copyright © 1991 by American Physiological Society

ARTICLES

IgG from amyotrophic lateral sclerosis affects tubular calcium channels of skeletal muscle

O. Delbono, J. Garcia, S. H. Appel and E. Stefani
Department of Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, Texas 77030.

Amyotrophic lateral sclerosis (ALS) is a devastating human disease of upper and lower motoneurons. We studied the action of the immunoglobulin G (IgG) from ALS and disease control patients on dihydropyridine (DHP)-sensitive Ca2+ channels in single mammalian skeletal muscle fibers with the double Vaseline gap technique. The peak of the Ca2+ current (ICa) and the charge movement were reduced when the fibers were incubated in ALS IgG. These effects were lost when the IgG was boiled or adsorbed with skeletal tubular membranes. ALS IgG reduced skeletal muscle ICa in a similar fashion as nifedipine; the ICa blockade was voltage dependent, and the associated charge movement was reduced. These observations suggest that IgG from ALS patients reacts with the skeletal muscle DHP-sensitive Ca2+ channels or some associated regulatory moiety.

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