Fig. 6.

Triglyceride-rich lipoproteins are not a significant source of triglyceride in the kidney. A, B: Whole body blockade of MTTP was achieved using BMS-212122 (MTTPi, N = 4–5/group) given orally for 7 days or vehicle (DMSO) equivalent to mice. Data obtained after a 16 h fast. A: VLDL triglyceride levels obtained from ultracentrifugation of plasma of mice treated with MTTPi or vehicle. B: Kidney and liver triglyceride content of fasted mice treated with either MTTPi vehicle. C, D: Liver-specific blockade of MTTP was achieved with a liver-specific knockout of MTTP (L-Mttp^−/−, N = 4–6/group). C: Plasma triglycerides of L-Mttp^−/− mice versus floxed littermate controls. D: Kidney and liver triglyceride content of L-Mttp^−/− mice versus littermate controls. E: Summary figure of research data: 1) During fasting Angptl4 inhibits LPL, so that triglycerides on lipoproteins cannot be hydrolyzed, thus fatty acid-loaded albumin is the primary exogenous source of fatty acids for the kidney. 2) Though CD36 is amply expressed on the kidney, it is not required for the transport of fatty acids into the kidney during fasting, which might involve nonreceptor diffusion across the member. 3) Though CD36 does not appear to act as a major transporter, it does not discount that other transporters may exist. 4) Once inside the cell, fatty acid is shuttled to the mitochondria where it can be oxidized for ATP. If the rate of fatty acid flux into the cells is far greater than the cells capacity for oxidization, excess fatty acids are stored in lipid droplets. Stored fatty acids can also be released from the lipid droplets and oxidized. Experiments were performed in male mice. *P < 0.05, #P < 0.05. *Comparison between feeding status using unpaired Student’s t-test. #Comparison between genotype using the two-way ANOVA Tukey’s multiple comparison test.