Figure 4.

Food deprivation induces a decrease in protein synthesis as determined with IV-SUnSET and IV-IHC-SUnSET. Mice were fed ad libitum (control) or deprived of food for 48 h (fasted), and the in vivo rates of protein synthesis in the heart (A, B), kidney (C, D), and TA skeletal muscle (E, F) were measured with IV-SUnSET as described in Materials and Methods. A, C, E) Representative images of WB analysis for puromycin (Puro) followed by Coomassie Blue (CB) staining to verify equal loading of proteins. B, D, F) Quantification of the puromycin-labeled peptides, expressed as a percentage of the values obtained in the control group. RLU, relative light units. A–F) All values are means ± se (for heart, n=8/group; for kidney and TA, n=4–5/group). G, H) In vivo rates of protein synthesis in the TA muscle were determined with an IV-IHC-SUnSET as described in Materials and Methods. G) Representative image of cross sections from TA muscles that were subjected to control or food-deprivation conditions, mounted adjacent to one another on a slide, and then subjected to IHC for puromycin. H) Puromycin staining intensity in individual fibers from both control and food-deprivation sections was expressed relative to the mean puromycin signal intensity of fibers in control sections and then plotted on a histogram. Average ± se staining intensity is indicated next to group labels in legend; n = 300 fibers/group from 5 independent pairs of muscles. *P < 0.05 vs. control.