Gel electrophoresis The 6 and 12% sodium

dodecyl sulfate-polyacrylamide gel electrophoreses (SDS-PAGE) were run to measure MyHC isoform expression and myosin:actin ratios in biopsy cross-sections and in single muscle fiber segments (11). For the 6% and 12% SDS-PAGE gels, the total acrylamide concentration was 4% and 3.5% in the stacking gel and 6 and 12% in the running gel, respectively. The gel matrix included 30% and 10% glycerol in Inhibitors,research,lifescience,medical the 6% and 12% SDS-PAGE, respectively, as described previously (11). Briefly, electrophoresis was performed at a constant current of 16 mA for 5 hours with a Tris-glycine electrode buffer (pH 8.3) at 15 °C (SE 600 vertical slab gel unit, Hoefer Scientific Instruments, San Francisco, CA, USA). The 12% SDS-PAGE gels

were stained with Coomassie blue (12), since the Coomassie staining penetrates Inhibitors,research,lifescience,medical the gel and allows accurate and highly reproducible quantitative protein analyses (12). The 6% SDS-PAGE used for single muscle fibers segment analyses were silver-stained, due to high sensitivity (13). All gels were subsequently scanned in a soft laser densitometer (Molecular Dynamics, Sunnyvale, CA, USA), with a high spatial resolution (50 μm pixel spacing) and 4096 optical density levels. The volume integration function was used to quantify the amount of protein on 12% and 6% gels (ImageQuant Inhibitors,research,lifescience,medical TL Software v. 2003.01, Amersham Biosciences, Uppsala, Sweden). These values were used to calculate myosin:actin protein Inhibitors,research,lifescience,medical ratios in both whole biopsies and single fibers, as well as to relate the amount of myosin and actin to the total protein of each fiber, and to quantify the percentage of each myosin isoform in whole biopsies. RNA extraction, cDNA synthesis and mRNA expression analyses Total RNA was extracted from frozen muscle tissue (5-10 mg) using

Qiagen RNeasy® Mini Kit (Qiagen, Inc., Valencia, CA, USA). Muscle Inhibitors,research,lifescience,medical tissue was homogenized using a rotor homogenizer (Eurostar Digital, IKA-Werke). Qiashredder™ (Qiagen, Inc.) columns were used to disrupt DNA. RNA was eluted from RNeasy® Mini columns with 30 ul of RNase free water. RNA was quantified until using Ribogreen® (Molecular Probes, Eugene, OR, USA), on a Plate Chameleon™ Multilabel Platereader (Hidex, Oy, Finland). Equal amounts (100 ng) of total RNA were synthesized into cDNA using Ready-To-Go™ You-Prime First-Strand-Beads, 0.66 μg random hexamers and 0.05 μg oligo-dT primers (all Amersham Biosciences, Uppsala, Sweden) selleck screening library according to the manufacturer’s instructions. The cDNA was diluted to a volume of 100 μl and stored at -80°C until RT-PCR quantification. Real-time PCR was used to quantify the mRNA levels for the dominating thick and thin filament proteins expressed in the human tibialis anterior muscle, i.e., the β/slow (type I) MyHC isoform and skeletal-βactin.