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Characterization of sarco(endo)plasmic reticulum Ca 2+ ‐ATPase (SERCA) expression and function in Zucker fa/fa obese rat skeletal muscle
Author(s) -
Vigna Chris,
Holloway Graham,
Bonen Arend,
Tupling A. Russell
Publication year - 2010
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.24.1_supplement.1048.12
Subject(s) - serca , chemistry , medicine , endocrinology , skeletal muscle , endoplasmic reticulum , atpase , biochemistry , enzyme , biology
The purpose of this study was to characterize SERCA expression and function in extensor digitorum longus (EDL) and soleus (SOL) muscles from Zucker fa/fa obese (321±5 g) and lean (233±10 g) control rats ( n =6/group). The rate of Ca 2+ ‐uptake in EDL and SOL homogenates was measured spectrofluorometrically using Indo‐1. Maximal Ca 2+ ‐ATPase activity (Vmax) was determined using a 96‐well spectrophotometric assay. When comparing Zucker to control rats, there were no differences (p>0.05) in Vmax in either EDL (592±40 vs. 536±31 μmol/g/min) or SOL (120±12 vs. 120±13). However, Ca 2+ ‐uptake rates were higher (p<0.05) in the SOL from Zucker fa/fa rats (4.10±0.30 μmol/g/min) when compared to control animals (2.92±0.61 μmol/g/min). In addition, the rate of Ca 2+ leak from Ca 2+ loaded SR vesicles in the SOL homogenate was lower (p<0.05) in Zucker fa/fa rats compared to controls. These observations were not mirrored in the EDL. Furthermore, the SERCA1a and SERCA2a contents were not different between genotypes in either tissue. These data suggest that the reduced rate of Ca 2+ leak in slow‐twitch skeletal muscle from Zucker fa/fa rats improves Ca 2+ ‐pumping efficiency and may result in a lower energy cost of Ca 2+ cycling. Research supported by NSERC Canada