Article: Transfer of exogenous cholesterol to microsomes of hepatocytes investigated with [3H]desmosterol tracer

The feasibility of using exogenous [3H]desmosterol as a mass metabolic tracer for exogenous non-esterified cholesterol in hepatocytes is investigated with albumin-bound non-esterified cholesterol containing [3H]desmosterol and [14C] cholesterol tracers. The amounts of uptake and metabolism of exogenous cholesterol monitored by either tracer are the same. In addition, the conversion of [3H]desmosterol into [3H]cholesterol by the delta 24-sterol reductase in the microsomes can be used as an estimate for the mass transfer of exogenous cholesterol to the microsomes. The results obtained indicate that only a small fraction of exogenous cholesterol that was transferred to the microsomes was metabolized into bile acids and steryl esters. The technique of estimating the mass transfer of exogenous cholesterol to the microsomes with [3H]desmosterol may be of importance in investigations dealing with the effect of exogenous plasma cholesterol on changes in the physiological functions of the endoplasmic reticulum in the cells.

Citing Articles

Movement of plasma-membrane sterols to the endoplasmic reticulum in cultured cells.

Slotte J, Bierman E Biochem J. 1987; 248(1):237-42.

PMID: 3435441 PMC: 1148524. DOI: 10.1042/bj2480237.

HPLC analysis of desmosterol, 7-dehydrocholesterol, and cholesterol.

Goh E, Colles S, Otte K Lipids. 1989; 24(7):652-5.

PMID: 2779370 DOI: 10.1007/BF02535083.

References

1.

Zlatkis A, ZAK B . Study of a new cholesterol reagent. Anal Biochem. 1969; 29(1):143-8. DOI: 10.1016/0003-2697(69)90017-7. View

2.

Bates S, Rothblat G . Regulation of cellular sterol flux and synthesis by human serum lipoproteins. Biochim Biophys Acta. 1974; 360(1):38-55. DOI: 10.1016/0005-2760(74)90178-7. View

3.

HEIDER J, Boyett R . The picomole determination of free and total cholesterol in cells in culture. J Lipid Res. 1978; 19(4):514-8. View

4.

Yousef I, Ho J, Jeejeebhoy K . Bile acid synthesis in isolated rat hepatocytes. Can J Biochem. 1978; 56(8):780-3. DOI: 10.1139/o78-118. View

5.

Long 3rd T, Jakoi L, Stevens R, QUARFORDT S . The sources of rat biliary cholesterol and bile acid. J Lipid Res. 1978; 19(7):872-8. View

6.

Gibbons G, Pullinger C . Utilization of endogenous and exogenous sources of substrate for cholesterol biosynthesis by isolated hepatocytes. Biochem J. 1979; 177(1):255-63. PMC: 1186364. DOI: 10.1042/bj1770255. View

7.

Goh E . Relationships between cholesterogenesis, microsomal sterols and HMG-CoA reductase in the perfused rat liver. Lipids. 1980; 15(9):624-30. DOI: 10.1007/BF02534011. View

8.

PORTMAN O, Alexander M, OMalley J . Metabolism of free and esterified cholesterol and apolipoproteins of plasma low and high density lipoproteins. Biochim Biophys Acta. 1980; 619(3):545-58. DOI: 10.1016/0005-2760(80)90106-x. View

9.

Schwartz C, VLAHCEVIC Z, Halloran L, SWELL L . An in vivo evaluation in man of the transfer of esterified cholesterol between lipoproteins and into the liver and bile. Biochim Biophys Acta. 1981; 663(1):143-62. DOI: 10.1016/0005-2760(81)90201-0. View

10.

Lodola A, Newsam R, Sumner I . A rapid method for the fractionation of isolated hepatocytes. Anal Biochem. 1981; 117(1):45-52. DOI: 10.1016/0003-2697(81)90689-8. View

11.

OMalley J, Soltys P, PORTMAN O . Interaction of free cholesterol and apoproteins of low and high density lipoproteins with isolated rabbit hepatocytes. J Lipid Res. 1981; 22(8):1214-24. View

12.

Itzhaki R, Gill D . A MICRO-BIURET METHOD FOR ESTIMATING PROTEINS. Anal Biochem. 1964; 9:401-10. DOI: 10.1016/0003-2697(64)90200-3. View

Transfer of Exogenous Cholesterol to Microsomes of Hepatocytes Investigated with [3H]desmosterol Tracer