Sterol metabolism. 3. The distribution and transport of sterols across the intestinal mucosa of the guinea pig

Glover, John L.; Green, C.

doi:10.1042/bj0670308

Cited by 83 publications

(21 citation statements)

References 16 publications

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“…In the diet and in the micellar phase in the intestinal lumen, the percentage of sitosterol is much greater than that of campesterol, whereas in the intestinal wall and in the subsequent stages of absorption in several animal species, the proportion of campesterol is much increased [11][12][13]. This is what would be predicted on the basis of the above results if absorption were mediated via incorporation into and exchange amongst the membranes and soluble lipoproteins of the mucosal cell [3 ]. Since cholesterol is incorporated into and exchanges amongst membranes more easily than either of the plant sterols, the plant sterols will be discriminated against more and more the deeper they penetrate into the mucosal cell and the more exchanges they undergo [14].…”

Section: Erythrocytessupporting

confidence: 64%

“…A further investigation of the role of the side chain of the sterol molecule has now been made using the major plant sterols present in the diet, campesterol and sitosterol, which differ from cholesterol only in the possession, respectively, of an extra methyl and ethyl group in the side chain. These, and other plant and fungal sterols, are poorly absorbed in the intestine compared with animal sterols and this specificity of absorption was attributed to the ability of sterols to enter the membranes and soluble lipoproteins of the intestinal cell [3,4].…”

Section: Introductionmentioning

confidence: 99%

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Incorporation of plant sterols into membranes and its relation to sterol absorption

Edwards

Green

1972

FEBS Letters

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Section: Erythrocytessupporting

confidence: 64%

Section: Introductionmentioning

confidence: 99%

Incorporation of plant sterols into membranes and its relation to sterol absorption

Edwards

Green

1972

FEBS Letters

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“…In view of such evidence, it is reasonable to suspect that cellular organelles play an active role in determining the specificity of sterol absorption. Although the specific transport sites may involve lipoproteins, as suggested by Glover and Green (42), there is as yet no direct evidence concerning the chemical nature of such sites.…”

Section: Discussionmentioning

confidence: 97%

Metabolism of Vitamin D. I. Preparation of Radioactive Vitamin D and Its Intestinal Absorption in the Rat*

Schachter¹,

Finkelstein²,

Kowarski³

1964

J. Clin. Invest.

168

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Vitamin D has been called "the most dominating single factor in the regulation of the absorption of calcium" (1). Although experiments with segments of small intestine in vitro have demonstrated that the vitamin is required to maintain an active transport mechanism for calcium in the mucosa (2-4), the molecular events underlying the action remain unknown. To define them, detailed information on the metabolism of vitamin D, now lacking, is needed.The metabolic fate of the vitamins D can be studied most effectively with radioactive compounds, for chemical methods of estimation are relatively insensitive or nonspecific, and biological assay is tedious and difficult. C14-vitamin D3 labeled at C3 (5) and randomly labeled C14-vitamin De (6) have been prepared by prior investigators, and with the latter material Kodicek and collaborators have provided much of the available metabolic data (7-10). The information remains limited, however, partly because it is difficult to prepare sufficient quantities of material of relatively high specific activity. Accordingly, the present studies were begun to develop more efficient methods for the preparation of radioactive vitamin D for metabolic studies. Tritium-labeled vitamin D3 and C14-labeled vitamin D, have been prepared, and the major pathways of transport and metabo-* Submitted for publication October 28, 1963; accepted December 26, 1963. Supported by U. S. Public Health Service grant AM-01483.Portions of this work were presented at the 55th Annual Meeting of the American Society for Clinical Investigation, Atlantic City, N. J., April 1963. lism in the rat identified (11). Vitamin D is absorbed chiefly into lymph, distributed widely in the tissues but accumulated in highest concentration in liver, and excreted mainly into bile. The present report describes in detail the preparation of the radioactive compounds and their intestinal absorption in the rat. Materials and MethodsPreparation of H'-vitamnin D,. Initial experiments demonstrated persistence of biological activity in a solution of vitamin D, in 80% acetic acid after 16 hours at 230 C in an atmosphere of N2. Therefore 1 g of crystalline vitamin D, under N, 1 was labeled 2 by catalytic exchange in tritiated acetic acid under identical conditions (schedule TR-1). The product, a brownish material in a vial under N,, was applied for thin-layer chromatography on plates of activated silicic acid gel 3 0.5 mm thick. Reference vitamin D, was applied to the outer margins. The plates were developed in the dark for 45 minutes with CHC13 as the solvent, dried briefly at room temperature, sprayed lightly with 0.001%o Rhodamine 6 G in acetone, and viewed under an ultraviolet lamp (maximal emission, 253.7 mA&) to localize the dark, absorbing band of vitamin D3. The bands of gel were scraped from the plates and eluted repeatedly with CHC13. Vitamin D in the eluate, and generally in the present studies, was estimated chemically with an SbCl, reagent (12). (Dried samples were treated with the SbCl3 reagent at room temperature for e...

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“…There is evidence that mucosal cells can discriminate in their uptake of individual free sterols such as cholesterol and plant sterols (17,18). Although the nature of this discriminatory process has not yet been elucidated, Glover and Green have proposed that the sterol absorption might be mediated via carrier lipoproteins and these lipoproteins might be specific for various sterols (19). However, there is evidence that f-sitosterol is taken up by mucosal cells (3).…”

Section: Methodsmentioning

confidence: 99%

β-Sitosterolemia and Xanthomatosis

Bhattacharyya¹,

Connor²

1974

J. Clin. Invest.

514

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A B S T R A C T Although the usual diet may contain 150-250 mg of plant sterols, chiefly f8-sitosterol, only trace amounts of these sterols have heretofore been found in human or animal blood and tissues. We now report elevated plant sterol levels in the blood and tissues of two sisters with extensive tendon xanthomas but normal plasma cholesterol levels. Besides. P-sitosterolemia and xanthomatosis, no other physical, mental, or biochemical abnormalities were detected.Repeatedly, the plasmas of the two sisters have contained 27.1 and 17.7 mg/100 ml of p-sitosterol, 9.7 and 8.2 mg/100 ml of campesterol, and 0.5 and 0.5 mg/100 ml of stigmasterol, respectively. These plant sterols constituted 15.6 and 11.3% of the total plasma sterols. Some 60% of the plasma f-sitosterol and campesterol was esterified; the measurable stigmasterol was entirely unesterified. The transport of the plasma P-sitosterol and campesterol was largely in low density lipoproteins (76 and 83%, respectively). High density lipoproteins carried the remainder. Plant sterols were barely detectable in the very low density lipoprotein fraction. Only trace amounts of stigmasterol could be detected in the low density and high density lipoprotein fractions. The plant sterol content of the red blood cells averaged 12-13 mg/100 ml packed cells or about 13% of the total sterols. Two tendon xanthoma biopsies with the usual high concentration of cholesterol had 36.7 and 4.0 mg of plant sterols/g dry wt, of which 25.7 and 2.9 mg were fi-sitosterol, entirely in the free form. Plant sterols were also found in adipose tissue This work was presented in part at the 65th Annual

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Sterol metabolism. 3. The distribution and transport of sterols across the intestinal mucosa of the guinea pig

Cited by 83 publications

References 16 publications

Incorporation of plant sterols into membranes and its relation to sterol absorption

Incorporation of plant sterols into membranes and its relation to sterol absorption

Metabolism of Vitamin D. I. Preparation of Radioactive Vitamin D and Its Intestinal Absorption in the Rat*

β-Sitosterolemia and Xanthomatosis

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