Isolation of Relaxing Particles from Rat Skeletal Muscles in Zonal Centrifuges

Journal Article · 30 April 1965 · Journal of General Physiology

DOI: https://doi.org/10.1085/jgp.48.5.737 · OSTI ID:1629497

Schuel, H. ^[1]; Lorand, L. ^[2]; Schuel, R. ^[2]; Anderson, N. G. ^[2]

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1. Northwestern Univ., Evanston, IL (United States). Dept. of Chemistry; Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Biology Division; DOE/OSTI
2. Northwestern Univ., Evanston, IL (United States). Dept. of Chemistry; Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Biology Division

Supernatants of rat skeletal muscle homogenates were fractionated by differential centrifugation and by zonal centrifugation in sucrose density gradients. Cytochrome oxidase was employed as an enzymatic marker for locating mitochondria. The subcellular fractions were also assayed for their ability to prevent the ATP-induced contraction of myofibrils. Both the mitochondrial and microsomal fractions obtained by differential fractionation were found to be rich in such relaxing activity, and the microsomal fraction was appreciably contaminated by mitochondria. In contrast to this, when fractionation was carried out by means of zonal centrifugation (4200 RPM x 205 min. to 40,000 RPM x 60 min.), relaxing activity was found to be associated only with particles having the sedimentation characteristics of microsomes (s_20,w estimated to be between 370 and 1880S). Relaxing activity was not detected in the regions of the gradient containing either the starting sample zone (soluble phase) or the mitochondrial peak. The microsomal relaxing particles showed negligible cytochrome oxidase activity.

• Research Organization: Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)
• Sponsoring Organization: USDOE Office of Science (SC), Biological and Environmental Research (BER). Biological Systems Science Division
• Grant/Contract Number: AC05-00OR22725
• OSTI ID: 1629497
• Journal Information: Journal of General Physiology, Journal Name: Journal of General Physiology Journal Issue: 5 Vol. 48; ISSN 0022-1295
• Publisher: Rockefeller University PressCopyright Statement
• Country of Publication: United States
• Language: English