Relative protein levels of ubiquitin-protein conjugates in M. quadriceps femoris of rats fed either a control diet (0 mg carnitine/ kg diet; Control) or a diet supplemented with 1250 mg carnitine/ kg diet (Carnitine) . (A) A representative immunoblot specific to ubiquitin is shown for three animals per group; immunoblots for the other animals revealed similar results. Reversible staining of nitrocellulose membranes with Ponceau S revealed equal loading of protein. (B) Bars represent data from densitometric analysis and represent means ± SD (n = 6/group); bars are expressed relative to the protein level of the control group (= 1.00). * indicates a significant difference to the control group (P < 0.05).