AJP - Endocrinology and Metabolism, Vol 245, Issue 5 463-E467, Copyright © 1983 by American Physiological Society
Absorption, distribution, and transport of vitamin D3 and 25-hydroxyvitamin D3 in the rat
S. Dueland, J. I. Pedersen, P. Helgerud and C. A. Drevon
The absorption of [14C]vitamin D3 and 25-[3H]hydroxyvitamin D3 into the
mesenteric lymph and portal vein after simultaneous instillation in rat
duodenum has been studied. The appearance of both isotopes in the
mesenteric lymph and portal vein during the first 2 h was negligible. After
2-4 h the isotopes appeared both in the lymph and portal vein. The
appearance of 25-[3H]hydroxyvitamin D3 in the mesenteric lymph was faster
than that of [14C]vitamin D3. Total recovery in the lymph during 24 h for
[14C]vitamin D3 and 25-[3H]hydroxyvitamin D3 was 15.2 and 14.3%,
respectively. While 80% of vitamin D3 in mesenteric lymph was recovered in
the chylomicrons (d less than 1.006 g/ml), 94% of 25-hydroxyvitamin D3 was
recovered in the protein fraction with d greater than 1.21 g/ml.
Seventy-one percent of 25-hydroxyvitamin D3 in the protein fraction was
associated with the alpha-globulins. Both vitamin D3 and 25-hydroxyvitamin
D3 that were recovered in the chylomicrons (d less than 1.006 g/ml) were
transferred in vitro to the lymph fraction with d greater than 1.006 g/ml.
Less than 12% of 25-hydroxyvitamin D3 was recovered in the liver after
intravenous injection of mesenteric lymph labeled with
25-[3H]hydroxyvitamin D3. Previously, under similar conditions 40% of
administered vitamin D3 was recovered in the liver.
