Functional characterization of intestinal L-carnitine transport

被引：28

作者：

Durán J.M. ^{[1
]}

Peral M.J. ^{[1
]}

Calonge M.L. ^{[1
]}

Ilundáin A.A. ^{[1
]}

机构：

[1] Depto. Fisiología y Biología Animal, Facultad de Farmacia, Universidad de Sevilla

来源：

The Journal of Membrane Biology | 2002年 / 185卷 / 1期

关键词：

Brush-border; Enterocytes; Intestine; L-Carnitine; OCTN;

D O I：

10.1007/s00232-001-0110-5

中图分类号：

学科分类号：

摘要：

The carnitine transporter OCTN2 is responsible for the renal reabsorption of filtered L-carnitine. However, there is controversy regarding the intestinal L-carnitine transport mechanism(s). In this study, the characteristics of L-carnitine transport in both, isolated chicken enterocytes and brush-border membrane vesicles (BBMV) were studied. In situ hybridization was also performed in chicken small intestine. Chicken enterocytes maintain a steady-state L-carnitine gradient of 5 to 1 and 90% of the transported L-carnitine remains in a readily diffusive form. After 5 min, L-Carnitine uptake into BBMV overshot the equilibrium value by a factor of 2.5. Concentrative L-carnitine transport is Na+-, membrane voltage- and pH-dependent, has a high affinity for L-carnitine (Km 26 - 31 μM) and a 1:1 Na+: L-carnitine stoichiometry. L-Carnitine uptake into either enterocytes or BBMV was inhibited by excess amount of cold L-carnitine > D-carnitine = acetyl-L-carnitine = γ-butyrobetaine > palmitoyl-L-carnitine > betaine > TEA, whereas alanine, histidine, GABA or choline were without significant effect. In situ hybridization studies revealed that only the cells lining the intestinal villus expressed OCTN2 mRNA. This is the first demonstration of the operation of a Na+/L-carnitine cotransport system in the apical membrane of enterocytes. This transporter has properties similar to those of OCTN2.

引用

页码：65 / 74

页数：9

共 32 条

[1]

Berardi S., Hagenbuch B., Carafoli E., Krahenbuhl S., Characterization of the endogenous carnitine transport and expression of a rat renal Na<sup>+</sup>-dependent carnitine transport system in Xenopus laevis oocytes, Biochem. J., 309, pp. 389-393, (1995)

[2]

Bradford M.M., A rapid and sensitive method for the quantification microgram quantities of protein utilizing the principle of protein dye binding, Anal. Biochem., 72, pp. 248-254, (1976)

[3]

Calonge M.L., Ilundain A., Bolufer J., Ionic dependence of Glycyl-sarcosine uptake by isolated chicken enterocytes, J. Cell Physiol., 138, pp. 579-585, (1989)

[4]

Gross C.J., Henderson L.M., Savaiano D.A., Uptake of L-carnitine, D-carnitine and acetyl-L-carnitine by isolated guinea-pig enterocytes, Biochim. Biophys. Acta, 886, pp. 425-433, (1986)

[5]

Gross C.J., Henderson L.M., Absorption of D-and L-carnitine by the intestine and kidney tubule in the rat, Biochim. Biophys. Acta, 772, pp. 199-219, (1984)

[6]

Gross C.J., Savaiano D.A., Effect of development and nutritional state on the uptake, metabolism and release of free and acetyl-L-carnitine by the rodent small intestine, Biochim. Biophys. Acta, 1170, pp. 265-274, (1993)

[7]

Gudjonsson H., Li B.U.K., Shug A.L., Olsen W.A., In vivo studies of intestinal carnitine absorption in rats, Gastroenterology, 88, pp. 1880-1887, (1985)

[8]

Hamilton J.W., Li B.U.K., Shug A.L., Olsen W.A., Carnitine transport in human intestinal biopsy specimens. Demonstration of an active transport system, Gastroenterology, 91, pp. 10-16, (1986)

[9]

Huang W., Shaikh S.N., Ganapathy M.E., Hopfer U., Leibach F.H., Carter A.L., Ganapathy V., Carnitine transport and its inhibition by sulfonylureas in human kidney proximal tubular epithelial cells, Biochem. Pharmacol., 58, pp. 1361-1370, (1999)

[10]

Huth P.J., Shug A.L., Properties of carnitine transport in rat kidney cortex slices, Biochim. Biophys. Acta, 602, pp. 621-634, (1980)

← 1 2 3 4 →