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Calcium sensitivity of fast‐and slow‐twitch human muscle fibers
Author(s) -
Ruff Robert L.
Publication year - 1989
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.880120107
Subject(s) - sarcolemma , calcium , fast twitch muscle , chemistry , fiber type , glycolysis , fiber , biophysics , muscle fibre , fibre type , oxidative phosphorylation , muscle contraction , anatomy , biochemistry , skeletal muscle , biology , metabolism , organic chemistry , membrane
Muscle fibers from the lateral gastrocnemius muscles of five normal adult males were chemically skinned (sarcolemma disrupted) and each fiber was divided into two parts for histochemical determination of fiber type and calcium‐induced tension measurements. The calcium concentration associated with half‐maximal tension was 2.5 μ M for fast‐twitch and 1.3–1.4 μ M for slow‐twitch fibers. Fast‐oxidative‐glycolytic (type 2A) and fast‐glycolytic (type 2B) fibers had similar calcium sensitivities. Maximum tensions (kg/ cm 2 ) were 2.24 for fast‐twitch and 2.19 for slow‐twitch fibers.