Calcium-tension relationships of muscle fibers from patients with periodic paralysis.
Lateral gastrocnemius muscle biopsies from a 26-year-old man with hyperkalemic periodic paralysis and a 23-year-old man with hypokalemic periodic paralysis were studied. Both patients came from families in which older relatives had developed a vacuolar myopathy in association with their periodic paralysis. Muscle fibers were chemically skinned, and individual fibers were studied with a low-compliance strain gauge. The tension generated by fibers was studied in baths with calcium concentrations from 10(-8) mol/L to 2.5 x 10(-5) mol/L. The Ca-tension relationships and maximal tensions (normalized to fiber cross-sectional area) of fast and slow twitch fibers were indistinguishable from those found in fibers from 5 normal subjects. The results reinforce earlier findings which suggested that loss of Ca-induced myofibril contraction was not the cause of paralysis in periodic paralysis.
Department of Neurology, Cleveland Veterans Administration Medical Center, OH 44106.
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D000328:Adult; D001706:Biopsy; D002118:Calcium / Q000502:physiology*; D006801:Humans; D008297:Male; D009119:Muscle Contraction / Q000502:physiology*; D009132:Muscles / Q000473:pathology / Q000503:physiopathology*; D010245:Paralyses, Familial Periodic / Q000473:pathology / Q000503:physiopathology*
D002118:Calcium