Abstract
To quantify the contribution of newly synthesized cholesterol to total plasma and biliary cholesterol under physiological conditions, unrestrained rats were infused intravenously with [1-13C]acetate (0. 6mmol/h per kg) from 12:00 to 24:00 h, and fractional and absolute cholesterol-synthesis rates were determined by mass isotopomer distribution analysis (MIDA). As bile diversion leads to changes in cholesterol metabolism, rats were equipped with permanent catheters in the bile duct and duodenum, allowing sampling of small amounts of bile from an intact enterohepatic circulation. For comparison, rats with chronic bile diversion were also studied. Fractional synthesis of plasma cholesterol was 10.8+/-1.7% (mean+/-S.D.) after 12 h in rats with intact circulation. Fractional synthesis of biliary cholesterol was significantly higher than that of plasma cholesterol, i.e. 16.5+/-2.0% (P<0.05) after 12 h. In contrast, no differences between fractional synthesis of cholesterol in plasma and bile were found in bile-diverted animals (31.8+/-2.1 and 33.1+/-3.3% respectively after 12 h). The calculated absolute rate of cholesterol biosynthesis increased from 53+/-10 to 221+/-19 micromol/day per kg after bile diversion. A comparison of MIDA results with those obtained from balance studies indicated that MIDA does not assess total body synthesis in rats, presumably because of incomplete equilibration of newly synthesized molecules with cholesterol in the plasma compartment. These studies demonstrate that the contribution of newly synthesized cholesterol to biliary cholesterol is higher than to plasma cholesterol under physiological conditions, probably reflecting bile-salt-induced secretion of newly formed cholesterol by the periportal hepatocytes.
Full Text
The Full Text of this article is available as a PDF (312.6 KB).
Selected References
These references are in PubMed. This may not be the complete list of references from this article.
- Björkhem I., Akerlund J. E. Studies on the link between HMG-CoA reductase and cholesterol 7 alpha-hydroxylase in rat liver. J Lipid Res. 1988 Feb;29(2):136–143. [PubMed] [Google Scholar]
- Cighetti G., Bosisio E., Galli G., Galli Kienle M. The effect of cholestyramine on liver HMG-CoA reductase and cholesterol 7 alpha-hydroxylase in various laboratory animals. Life Sci. 1983 Dec 19;33(25):2483–2488. doi: 10.1016/0024-3205(83)90156-x. [DOI] [PubMed] [Google Scholar]
- Dietschy J. M., Wilson J. D. Regulation of cholesterol metabolism. N Engl J Med. 1970 May 21;282(21):1179–1183. doi: 10.1056/NEJM197005212822105. [DOI] [PubMed] [Google Scholar]
- Edwards P. A., Lan S. F., Fogelman A. M. Alterations in the rates of synthesis and degradation of rat liver 3-hydroxy-3-methylglutaryl coenzyme A reductase produced by cholestyramine and mevinolin. J Biol Chem. 1983 Sep 10;258(17):10219–10222. [PubMed] [Google Scholar]
- Empen K., Lange K., Stange E. F., Scheibner J. Newly synthesized cholesterol in human bile and plasma: quantitation by mass isotopomer distribution analysis. Am J Physiol. 1997 Feb;272(2 Pt 1):G367–G373. doi: 10.1152/ajpgi.1997.272.2.G367. [DOI] [PubMed] [Google Scholar]
- Fukushima K., Ichimiya H., Higashijima H., Yamashita H., Kuroki S., Chijiiwa K., Tanaka M. Regulation of bile acid synthesis in the rat: relationship between hepatic cholesterol 7 alpha-hydroxylase activity and portal bile acids. J Lipid Res. 1995 Feb;36(2):315–321. [PubMed] [Google Scholar]
- Gamble W., Vaughan M., Kruth H. S., Avigan J. Procedure for determination of free and total cholesterol in micro- or nanogram amounts suitable for studies with cultured cells. J Lipid Res. 1978 Nov;19(8):1068–1070. [PubMed] [Google Scholar]
- Grundy S. M., Ahrens E. H., Jr Measurements of cholesterol turnover, synthesis, and absorption in man, carried out by isotope kinetic and sterol balance methods. J Lipid Res. 1969 Jan;10(1):91–107. [PubMed] [Google Scholar]
- Hardgrave J. E., Heller R. A., Herrera M. G., Scallen T. J. Immunotitration of 3-hydroxy-3-methylglutaryl-coenzyme A reductase in various physiological states. Proc Natl Acad Sci U S A. 1979 Aug;76(8):3834–3838. doi: 10.1073/pnas.76.8.3834. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Hellerstein M. K., Neese R. A. Mass isotopomer distribution analysis: a technique for measuring biosynthesis and turnover of polymers. Am J Physiol. 1992 Nov;263(5 Pt 1):E988–1001. doi: 10.1152/ajpendo.1992.263.5.E988. [DOI] [PubMed] [Google Scholar]
- Iglesias J., Gonzalez-Pacanowska D., Marco C., Garcia-Peregrin E. Cholesterol synthesis and esterification in isolated enterocytes: regulation by cholesterol and cholestyramine feeding. Lipids. 1993 Jun;28(6):549–553. doi: 10.1007/BF02536087. [DOI] [PubMed] [Google Scholar]
- Kinugasa T., Uchida K., Kadowaki M., Takase H., Nomura Y., Saito Y. Effect of bile duct ligation on bile acid metabolism in rats. J Lipid Res. 1981 Feb;22(2):201–207. [PubMed] [Google Scholar]
- Kuipers F., Dijkstra T., Havinga R., van Asselt W., Vonk R. J. Acute effects of pentobarbital-anaesthesia on bile secretion. Biochem Pharmacol. 1985 May 15;34(10):1731–1736. doi: 10.1016/0006-2952(85)90642-2. [DOI] [PubMed] [Google Scholar]
- Kuipers F., Havinga R., Bosschieter H., Toorop G. P., Hindriks F. R., Vonk R. J. Enterohepatic circulation in the rat. Gastroenterology. 1985 Feb;88(2):403–411. doi: 10.1016/0016-5085(85)90499-8. [DOI] [PubMed] [Google Scholar]
- Li A. C., Tanaka R. D., Callaway K., Fogelman A. M., Edwards P. A. Localization of 3-hydroxy-3-methylglutaryl CoA reductase and 3-hydroxy-3-methylglutaryl CoA synthase in the rat liver and intestine is affected by cholestyramine and mevinolin. J Lipid Res. 1988 Jun;29(6):781–796. [PubMed] [Google Scholar]
- Neese R. A., Faix D., Kletke C., Wu K., Wang A. C., Shackleton C. H., Hellerstein M. K. Measurement of endogenous synthesis of plasma cholesterol in rats and humans using MIDA. Am J Physiol. 1993 Jan;264(1 Pt 1):E136–E147. doi: 10.1152/ajpendo.1993.264.1.E136. [DOI] [PubMed] [Google Scholar]
- Raicht R. F., Cohen B. I., Shefer S., Mosbach E. H. Sterol balance studies in the rat. Effects of dietary cholesterol and beta-sitosterol on sterol balance and rate-limiting enzymes of sterol metabolism. Biochim Biophys Acta. 1975 Jun 23;388(3):374–384. doi: 10.1016/0005-2760(75)90096-x. [DOI] [PubMed] [Google Scholar]
- Robins S. J., Brunengraber H. Origin of biliary cholesterol and lecithin in the rat: contribution of new synthesis and preformed hepatic stores. J Lipid Res. 1982 May;23(4):604–608. [PubMed] [Google Scholar]
- Robins S. J., Fasulo J. M., Collins M. A., Patton G. M. Evidence for separate pathways of transport of newly synthesized and preformed cholesterol into bile. J Biol Chem. 1985 Jun 10;260(11):6511–6513. [PubMed] [Google Scholar]
- Robins S. J., Fasulo J. M., Lessard P. D., Patton G. M. Hepatic cholesterol synthesis and the secretion of newly synthesized cholesterol in bile. Biochem J. 1993 Jan 1;289(Pt 1):41–44. doi: 10.1042/bj2890041. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Ruckebusch Y. Motor functions of the intestine. Adv Vet Sci Comp Med. 1981;25:345–369. [PubMed] [Google Scholar]
- Scheibner J., Fuchs M., Schiemann M., Tauber G., Hörmann E., Stange E. F. Bile acid synthesis from newly synthesized vs. preformed cholesterol precursor pools in the rat. Hepatology. 1993 Jun;17(6):1095–1102. [PubMed] [Google Scholar]
- Singer I. I., Kawka D. W., Kazazis D. M., Alberts A. W., Chen J. S., Huff J. W., Ness G. C. Hydroxymethylglutaryl-coenzyme A reductase-containing hepatocytes are distributed periportally in normal and mevinolin-treated rat livers. Proc Natl Acad Sci U S A. 1984 Sep;81(17):5556–5560. doi: 10.1073/pnas.81.17.5556. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Smit M. J., Temmerman A. M., Havinga R., Kuipers F., Vonk R. J. Short- and long-term effects of biliary drainage on hepatic cholesterol metabolism in the rat. Biochem J. 1990 Aug 1;269(3):781–788. doi: 10.1042/bj2690781. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Spady D. K., Dietschy J. M. Sterol synthesis in vivo in 18 tissues of the squirrel monkey, guinea pig, rabbit, hamster, and rat. J Lipid Res. 1983 Mar;24(3):303–315. [PubMed] [Google Scholar]
- Stange E. F., Dietschy J. M. Age-related decreases in tissue sterol acquisition are mediated by changes in cholesterol synthesis and not low density lipoprotein uptake in the rat. J Lipid Res. 1984 Jul;25(7):703–713. [PubMed] [Google Scholar]
- Stellaard F., Sackmann M., Sauerbruch T., Paumgartner G. Simultaneous determination of cholic acid and chenodeoxycholic acid pool sizes and fractional turnover rates in human serum using 13C-labeled bile acids. J Lipid Res. 1984 Dec 1;25(12):1313–1319. [PubMed] [Google Scholar]
- Turley S. D., Andersen J. M., Dietschy J. M. Rates of sterol synthesis and uptake in the major organs of the rat in vivo. J Lipid Res. 1981 May;22(4):551–569. [PubMed] [Google Scholar]
- Turley S. D., Dietschy J. M. The contribution of newly synthesized cholesterol to biliary cholesterol in the rat. J Biol Chem. 1981 Mar 10;256(5):2438–2446. [PubMed] [Google Scholar]
- Twisk J., Hoekman M. F., Mager W. H., Moorman A. F., de Boer P. A., Scheja L., Princen H. M., Gebhardt R. Heterogeneous expression of cholesterol 7 alpha-hydroxylase and sterol 27-hydroxylase genes in the rat liver lobulus. J Clin Invest. 1995 Mar;95(3):1235–1243. doi: 10.1172/JCI117773. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Vonk R. J., van Doorn A. B., Strubbe J. H. Bile secretion and bile composition in the freely moving, unanaesthetized rat with a permanent biliary drainage: influence of food intake on bile flow. Clin Sci Mol Med. 1978 Sep;55(3):253–259. doi: 10.1042/cs0550253. [DOI] [PubMed] [Google Scholar]