Apolipoprotein B synthesis in rat small intestine: regulation by dietary triglyceride and biliary lipid

Journal Article · Wed Jan 01 04:00:00 EST 1986 · J. Lipid Res.; (United States)

OSTI ID:5810007

Davidson, N O; Kollmer, M E; Glickman, R M

Apolipoprotein B (apoB) synthesis rates have been determined, in vivo, in rat enterocytes. Following intralumenal administration of a pulse of (/sup 3/H)leucine, newly synthesized apoB was quantitated by specific immunoprecipitation and compared to (/sup 3/H)leucine incorporation into total, trichloroacetic acid-insoluble protein. ApoB synthesis rates were determined after acute administration of either 0.1 or 1 g of triglyceride to fasting animals. No differences were found at any time from 90 min to 6 hr after challenge and values were not different from the basal values established in fasted controls. Animals rechallenged with triglyceride after 8 days' intake of fat-free chow also failed to demonstrate a change in intestinal apoB synthesis rate. By contrast, enterocyte content of apoB appeared to fall, temporarily, with the onset of active triglyceride flux. Groups of animals were then subjected to external bile diversion for 48 hr, a maneuver designed to remove all lumenal sources of lipid. Jejunal apoB synthesis rates fell by 43% (from 0.76% +/- 0.14 to 0.43% +/- 0.12, P less than 0.001), a change that was completely prevented by continuous replacement with 10 mM Na taurocholate. The suppression of jejunal apoB synthesis, induced by prolonged bile diversion, was reversed after 14 hr, but not 8 hr, of intralumenal perfusion with 10 mM Na taurocholate. The addition of micellar fatty acid-monoolein to the perfusate for 4 hr produced no further change in apoB synthesis. Ileal apoB synthesis rates fell by 70% (from 0.61% +/- 0.15 to 0.18% +/- 0.10, P less than 0.001) following 48 hr external bile diversion, a change that was only partially prevented by continuous bile salt replacement. These results suggest that jejunal apoB synthesis demonstrates bile salt dependence but not regulation by acute triglyceride flux.

• Research Organization: Columbia Univ., New York, NY
• OSTI ID: 5810007
• Journal Information: J. Lipid Res.; (United States), Journal Name: J. Lipid Res.; (United States) Vol. 1; ISSN JLPRA
• Country of Publication: United States
• Language: English

Related Subjects

550201* -- Biochemistry-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
AMINO ACIDS
ANIMALS
APOLIPOPROTEINS
BILE
BIOCHEMICAL REACTION KINETICS
BIOLOGICAL MATERIALS
BIOSYNTHESIS
BODY
BODY FLUIDS
CARBOXYLIC ACIDS
DIGESTIVE SYSTEM
ESTERS
GASTROINTESTINAL TRACT
IMMUNOASSAY
IMMUNOLOGY
IN VIVO
INTESTINES
ISOTOPE APPLICATIONS
KINETICS
LABELLED COMPOUNDS
LEUCINE
LIPIDS
LIPOPROTEINS
MAMMALS
MATERIALS
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANS
PROTEINS
RADIOASSAY
RADIOIMMUNOASSAY
RADIOIMMUNOLOGY
RATS
REACTION KINETICS
RODENTS
SMALL INTESTINE
SYNTHESIS
TRACER TECHNIQUES
TRIGLYCERIDES
TRITIUM COMPOUNDS
VERTEBRATES