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Actomyosin ATPase. I. Quantitative measurement of activity in cryostat sections
Author(s) -
Mabuchi K.,
Sréter F. A.
Publication year - 1980
Publication title -
muscle and nerve
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.025
H-Index - 145
eISSN - 1097-4598
pISSN - 0148-639X
DOI - 10.1002/mus.880030307
Subject(s) - myofibril , cryostat , atpase , chemistry , skeletal muscle , sarcoplasm , biochemistry , oxidative phosphorylation , glycolysis , biophysics , enzyme , anatomy , biology , endoplasmic reticulum , physics , superconductivity , quantum mechanics
A method for the quantitative study of the actomyosin ATPase activity (Ca, MG‐ATPase) in thin sections cut in a cryostat is presented. This method is based on the liberation of 32 P from [γ 32 P]ATP or 45 Ca phosphate precipitation. The advantage of this method lies in the requirement for only a small muscle sample and the availability of serially cut sections for other assays including Ca uptake by sarcoplasmic reticulum and histochemical tests for oxidative and glycolytic enzymes. The actomyosin ATPase activity for various types of muscles determined by this method showed the same sequence found in isolated protein, that is, fast‐twitch skeletal > slow‐twitch skeletal > cardiac. The Ca, Mg‐ATPase of cryostat sections showed Ca sensitivity. The fact that the sections retained Ca sensitivity at 37°C, in contrast to myofibrils, which have been reported to lose Ca sensitivity at this temperature, indicates that the structural integrity of the contractile and regulatory apparatus is preserved to a higher degree in sections than in isolated myofibrils.