Vitamin placental transport

Rajan, D. P., et al. Human placental sodium-dependent vitamin C transporter (SVCT2) molecular cloning and transport function. Biochem. Biophys. Res. Commun. 1999, 262, 762-768. 

The circulating levels of l,25(OH)2D3 rise progressively towards the end of pregnancy, probably in response to the increased mineral demands. At the same time, an extra-renal synthesis of l,25(OH)2D3 takes place in the fetoplacental unit [4,47,48]. This synthesis is thought to occur in the decidual cells rather than in the placenta itself, although some controversy still remains upon the exact location of this process. Placental tissues have also been shown to contain specific receptors for l,25(OH)2D3 [49] as well as the faculty to synthesize the small calbindin (9 kDa) [50], However, the transplacental calcium transport is independent of the overall maternal vitamin D status [51]. The hypothesis of a differential regulation of calcium transport within the feto/placental unit may be in relation with the in situ synthesis of l,25(OH)2D3 or the fetal synthesis of this hormone. 

Schenker, S., Johnson, R. F., Mahuren, J. D., Henderson, G. I., and Cobum, S. P. (1992). Human placental vitamin B-6 (pyridoxal) transport—normal characteristics and effects of ethanol. Am. J. PhysioL 262, R966-R974. 

Some recent studies on vitamin transport using membrane vesicles include those of vitamin B6 by rat kidney brush border membranes (Bowman et al, 1990), ascorbic acid by teleost intestinal brush border membranes (Mafha et ai, 1993), biotin by human kidney brush border membranes (Baur and Baumgartner, 1992), pantothenate by human placental brush border membranes (Grassl, 1992), folate and riboflavin by rabbit intestinal brush border membranes (Said and Mohammadkhani, 1993a,b Said et al, 1993), and thiamine by rat small intestine basolateral membranes (Laforenza et al, 1993). Bile acid transport in human placental, rat ileal, and rabbit small intestinal brush border membrane vesicles (Dumaswala et al, 1993 Gong et al, 1991 Kramer et al, 1993) and the effect of vitamin D status... 

Folate (vitamin Bg) is a low-molecular-weight (441 Da) compound essential in cell proliferation and for the biosynthesis of methionine, serine, deoxythymine add, and purine. Folate is internalized via two independent pathways either by transport of folate by the folate reeeptor or as 5-methyl-tetrahydrofolate by the reduced folate carrier. The expression of folate receptor (FR) in healthy tissue is limited to activated macrophages, placental cells, and the apical surface of polarized epithelia, where it is present in different isoforms [56]. The overexpression of FR on a broad range of solid tumors (ovary, lung, breast, kidney, brain, endometrium, and colon) makes it a suitable target for selective tumor drug delivery (for review, see [57J). 

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