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Characterization of the translocation process of vitamin D3 from the skin into the circulation.
Endocrinology. 1994 Aug; 135(2):655-61.E

Abstract

The cutaneous synthesis of vitamin D3 and the subsequent translocation of vitamin D3 into the circulation are two key steps in the vitamin D endocrine system. To study the kinetic aspects of cutaneous synthesis and translocation of vitamin D3, both in vitro and in vivo chicken models have been developed. To assess the capacity of chicken skin to generate vitamin D3, the concentrations of 7-dehydrocholesterol (7-DHC) in different skin areas were determined. It was found that the highest concentration of 7-DHC was in the leg skin (3524 +/- 937 ng cm-2), which was about 30 times greater than that in the back (120 +/- 62 ng cm-2). Whole body exposure of chickens to UV-B radiation (0.5 J cm-2) resulted in the production of previtamin D3 (preD3) in the skin of the legs and feet (43 +/- 7 and 54 +/- 17 ng cm-2, respectively), whereas no preD3 was detected in the back skin. In vitro, at 40 C, the forward (k1) and reverse (k2) rate constants of the preD3<-->vitamin D3 reaction in the leg skin were greatly increased compared to those in n-hexane (k1, 0.367 vs. 0.0369 h-1; k2, 0.042 vs. 0.0059 h-1). In vivo, the determined rate constants k1, k2, and k3 for the consecutive reactions preD3<-->vitamin D3-->vitamin D3 were 0.257, 0.034, and 0.114 h-1, respectively. To evaluate the circulating concentration of vitamin D3 in response to UV-B radiation, chicken legs were irradiated. The time course revealed a 4-fold increase in the circulating concentration of vitamin D3, with a peak about 30 h postradiation. No appreciable amount of preD3 could be detected in the circulation in the early hours after UV-B radiation, suggesting the existence of a process responsible for the specific translocation of vitamin D3 from the skin into the circulation.

Authors+Show Affiliations

Vitamin D, Skin, and Bone Research Laboratory, Boston University School of Medicine, Massachusetts 02118.No affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, U.S. Gov't, Non-P.H.S.
Research Support, U.S. Gov't, P.H.S.

Language

eng

PubMed ID

8033813

Citation

Tian, X Q., et al. "Characterization of the Translocation Process of Vitamin D3 From the Skin Into the Circulation." Endocrinology, vol. 135, no. 2, 1994, pp. 655-61.
Tian XQ, Chen TC, Lu Z, et al. Characterization of the translocation process of vitamin D3 from the skin into the circulation. Endocrinology. 1994;135(2):655-61.
Tian, X. Q., Chen, T. C., Lu, Z., Shao, Q., & Holick, M. F. (1994). Characterization of the translocation process of vitamin D3 from the skin into the circulation. Endocrinology, 135(2), 655-61.
Tian XQ, et al. Characterization of the Translocation Process of Vitamin D3 From the Skin Into the Circulation. Endocrinology. 1994;135(2):655-61. PubMed PMID: 8033813.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Characterization of the translocation process of vitamin D3 from the skin into the circulation. AU - Tian,X Q, AU - Chen,T C, AU - Lu,Z, AU - Shao,Q, AU - Holick,M F, PY - 1994/8/1/pubmed PY - 1994/8/1/medline PY - 1994/8/1/entrez SP - 655 EP - 61 JF - Endocrinology JO - Endocrinology VL - 135 IS - 2 N2 - The cutaneous synthesis of vitamin D3 and the subsequent translocation of vitamin D3 into the circulation are two key steps in the vitamin D endocrine system. To study the kinetic aspects of cutaneous synthesis and translocation of vitamin D3, both in vitro and in vivo chicken models have been developed. To assess the capacity of chicken skin to generate vitamin D3, the concentrations of 7-dehydrocholesterol (7-DHC) in different skin areas were determined. It was found that the highest concentration of 7-DHC was in the leg skin (3524 +/- 937 ng cm-2), which was about 30 times greater than that in the back (120 +/- 62 ng cm-2). Whole body exposure of chickens to UV-B radiation (0.5 J cm-2) resulted in the production of previtamin D3 (preD3) in the skin of the legs and feet (43 +/- 7 and 54 +/- 17 ng cm-2, respectively), whereas no preD3 was detected in the back skin. In vitro, at 40 C, the forward (k1) and reverse (k2) rate constants of the preD3<-->vitamin D3 reaction in the leg skin were greatly increased compared to those in n-hexane (k1, 0.367 vs. 0.0369 h-1; k2, 0.042 vs. 0.0059 h-1). In vivo, the determined rate constants k1, k2, and k3 for the consecutive reactions preD3<-->vitamin D3-->vitamin D3 were 0.257, 0.034, and 0.114 h-1, respectively. To evaluate the circulating concentration of vitamin D3 in response to UV-B radiation, chicken legs were irradiated. The time course revealed a 4-fold increase in the circulating concentration of vitamin D3, with a peak about 30 h postradiation. No appreciable amount of preD3 could be detected in the circulation in the early hours after UV-B radiation, suggesting the existence of a process responsible for the specific translocation of vitamin D3 from the skin into the circulation. SN - 0013-7227 UR - https://www.unboundmedicine.com/medline/citation/8033813/Characterization_of_the_translocation_process_of_vitamin_D3_from_the_skin_into_the_circulation_ L2 - https://academic.oup.com/endo/article-lookup/doi/10.1210/endo.135.2.8033813 DB - PRIME DP - Unbound Medicine ER -