Mechanisms of absorption, transport, and storage of vitamin A-by using rats and polar animals-

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Two polar bears, 8 Arctic foxes, 6 bearded seals, 22 glaucous gulls, 5 fulmars, 4 Bruenich's guillemots, 6 ringed seals, 5 hooded seals, 6 puffins, and 7 Svalbard reindeers were caught in the Svalbard archipelago (situated at lat. 80 N). Fresh organs, namely, the liver, kidney, spleen, lung, and jejunum were investigated with gold chloride staining, fluorescence microscopy for autofluorescence of vitamin A, hematoxylin and eosin staining, azan staining, Ishii-Ishii's silver impregnation, transmission electron microscopy and high-performance liquid chromatography.The mammals and birds stored a large amount of vitamin A in the liver [23,300 (polar bear, n=2), 18,439*2,314 (Arctic fox, n=8), 5956*5857 (bearded seal, n=6), 1,551*2,486 (ringed seal, n=6), 921*264 (Svalbard reindeer, n=7), 4,710*3,164 (glaucous gull, n=22), 1,589*225 (Bruenich's guiHemot, n=4), and 1183*589 (puffin, n=6) nmole retinyl ester/g wet tissue]. Very strong autofluorescence of vitamin A emanated from the non-parenchymal cells in the liver. These cells showed positive reaction with gold chloride and stained black. Electronmicroscopically these cells existed in the perisinusoidal space of Disse and contained many lipid droplets within the cytoplasm. These anamals showed no hepatic fibrosis though they are in naturally occurred hypervitaminosis A.These findings suggest that these vitamin A-storihg cells are hepatic stellate cells and the Arctic animals that exist in a higher position of the food web in the Arctic area have well-developed vitamin A-storing mechanisms in the hepatic stellate cells.