(Na+ + K+)-ATPase activity of crude homogenates of rat skeletal muscle as estimated from their K+-dependent 3-O-methylfluorescein phosphatase activity

Aage Nørgaard*, Keld Kjeldsen, Otto Hansen

*Corresponding author af dette arbejde

    Publikation: Bidrag til tidsskriftArtikelForskningpeer review

    Abstract

    A highly sensitive fluorimetric assay using 3-O-methylfluorescein phosphate as substrate was used in the determination of K+-dependent phosphatase activity in preparations of rat skeletal muscle. The gastrocnemius muscle was chosen because of mixed fibre composition. Crude, detergent treated homogenate was used so as to avoid loss of activity during purification. K+-dependent phosphatase activities in the range 0.19-0.37 μmol · (g wet weight)-1 · min-1 were obtained, the value decreasing with age and K+-deficiency. Complete inhibition of the K+-dependent phosphatase was obtained with 10-3 M ouabain. Using a KSCN-extracted muscle enzyme the intimate relation between K+-dependent phosphatase activity and (Na+ + K+)-activated ATP hydrolysis could be demonstrated. A molecular activity of 620 min-1 was estimated from simultaneous determination of K+-dependent phosphatase activity and [3H]ouabain binding capacity using the partially purified enzyme preparation. The corresponding enzyme concentration in the crude homogenates was calculated and corresponded well with the number of [3H]ouabain binding sites measured in intact muscles or biopsies hereof.

    OriginalsprogEngelsk
    Sider (fra-til)203-209
    Antal sider7
    TidsskriftBBA - Biomembranes
    Vol/bind770
    Udgave nummer2
    DOI
    StatusUdgivet - 14 mar. 1984

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    Udforsk hvilke forskningsemner '(Na+ + K+)-ATPase activity of crude homogenates of rat skeletal muscle as estimated from their K+-dependent 3-O-methylfluorescein phosphatase activity' indeholder.

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