title: Photosynthesis of previtamin D3 in human skin and the physiologic consequences.
abstract: Photosynthesis of previtamin D3 can occur throughout the epidermis in the dermis when hypopigmented Caucasian skin is exposed to solar ultraviolet radiation. Once previtamin D3 is formed in the skin, it undergoes a temperature-dependent thermal isomerization that takes at least 3 days to complete. The vitamin D-binding protein preferentially translocates the thermal product, vitamin D3, into the circulation. These processes suggest a unique mechanism for the synthesis, storage, and slow, steady release of vitamin D3 from the skin into the circulation.
mesh_terms: D000818:Animals; D002352:Carrier Proteins / Q000378:metabolism; D002762:Cholecalciferol / Q000096:biosynthesis* / Q000031:analogs & derivatives; D002775:Cholestadienols / Q000096:biosynthesis*; D004307:Dose-Response Relationship, Radiation; D006358:Hot Temperature; D006801:Humans; D007536:Isomerism; D010777:Photochemistry; D051381:Rats; D012867:Skin / Q000166:cytology / Q000378:metabolism*; D014466:Ultraviolet Rays; D014807:Vitamin D / Q000378:metabolism; D014809:Vitamin D-Binding Protein
chemical_list: D002352:Carrier Proteins; D002775:Cholestadienols; D014809:Vitamin D-Binding Protein; D014807:Vitamin D; D002762:Cholecalciferol; C025168:previtamin D(3)