Figure 4.

A low-Lys diet increases oxidative muscle fibers, and an amino acid profile mimicking the low-Lys serum enhances fatty acid uptake.A, six-week-old male Wistar rats were fed experimental diets ad libitum for 2 weeks. Frozen muscle sections were stained with ATPase staining preincubated with sodium barbital solution adjusted to pH 4.7 or 4.2 for 5 min to stain slow-twitch or fast-twitch. At pH 4.2, myosin, except for the type I myosin ATPase, is inactivated. Thus, type I myosin fibers are strongly stained as black at pH 4.2. B, well-differentiated L6 cells were cultured in the experimental medium for 2 days, and 100 μM BODIPYFLC₁₂ were added to the cells during the last 4 h. Lipids were extracted by Folch's method and fluorescent intensity was measured (n = 3, means, ±S.E.) ∗p < 0.01, versus Full medium. C and D, frozen sections of MLT were immuno-stained with anti-FATP4 antibody (green), and nucleus was stained with Hoechst33342 (blue). The images were obtained with the confocal microscope (C). The green fluorescent intensity of each picture was quantified by Image J. Values were shown in the graph (D). n = 3, means ± S.E., ∗p < 0.01 versus CN. E, acetyl-carnitine concentration in the serum from each rat was measured using LC MS/MS (n = 3, means ± S.E.) ∗p < 0.01 versus CN.