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ATP utilization for calcium uptake and force production in different types of human skeletal muscle fibres
Author(s) -
Szentesi P.,
Zaremba R.,
Mechelen W.,
Stienen G. J. M.
Publication year - 2001
Publication title -
the journal of physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.802
H-Index - 240
eISSN - 1469-7793
pISSN - 0022-3751
DOI - 10.1111/j.1469-7793.2001.0393i.x
Subject(s) - skeletal muscle , calcium , production (economics) , skeletal muscle fibers , chemistry , biophysics , microbiology and biotechnology , anatomy , biology , economics , organic chemistry , macroeconomics
1 The contractile properties and ATPase activity of skinned human skeletal muscle fibres from vastus lateralis were examined. Fibre types were resolved from single fibre segments by SDS‐polyacrylamide gel electrophoresis. ATPase activity was determined by enzymatic coupling of ATP resynthesis to the oxidation of NADH. 2 The partitioning of ATPase activity into (a) calcium‐activated activity due to actomyosin (AM) interaction, (b) calcium‐activated activity of the sarcoplasmic reticular (SR) calcium pump, and (c) basal (calcium independent) activity was investigated by comparing ATP utilization before and after exposure of the preparations for 30 min to a solution containing 0.5 % Triton X‐100, which effectively abolished the SR ATPase activity. 3 Partitioning of ATPase activity was also determined by measuring ATP utilization and force at different concentrations of butanedione monoxime (BDM), which inhibits AM interaction. 4 The results obtained with Triton X‐100 and BDM were similar. At saturating Ca 2+ concentrations and 20 °C, the AM, SR and basal ATPase activities per litre cell volume (± s.e.m. ) amounted to 46 ± 4, 51 ± 4 and 19 ± 2 μ m s −1 in type I fibres (n = 21), 139 ± 14, 69 ± 8 and 30 ± 3 μ m s −1 in type IIA fibres (n = 25), 137 ± 22, 175 ± 28 and 26 ± 8 μ m s − 1 in type IIA/B fibres (n = 4) and 108 ± 13, 169 ± 42 and 32 ± 8 μ m s −1 in type IIB fibres (n = 2). 5 These results indicate that ATP utilization for SR Ca 2+ pumping in fast fibres is considerably larger than in slow fibres. The SR ATPase activity in human muscle represents a considerable fraction of the total (AM + SR + basal) ATPase activity.