Tracking Lipid Source in Mice

To discriminate between FA- or lipoprotein-derived lipids, 5 μCi [9,10-³H(N)]-oleic acid (Hartmann Analytics, Braunschweig, Germany) were complexed with Na-oleate and BSA and injected in 200 μl PBS intravenously (i.v.) into WT and iDKO mice (Vujic et al., 2017 (link)). For lipoprotein injection, human VLDL (2.44 mg TG) was labeled with 1 μCi [9,10-³H(N)]-triolein (Perkin Elmer, Waltham, MA) and administered i.v. (200 μl). Animals were injected at 8 a.m. and sacrificed 1 h later to collect plasma and organs. To trigger VLDL secretion from the liver, mice were injected i.v. at 8 a.m., followed by overnight fasting the same day (8 p.m. – 8 a.m.) and sacrificed at 8 a.m. the following day. Radioactivity in plasma and tissues was determined by liquid scintillation counting.