TY - JOUR
T1 - Intestinal absorption of vitamin D sterols
T2 - Differential absorption into lymph and portal blood in the rat
AU - Maislos, Maximo
AU - Silver, Justin
AU - Fainaru, Menahem
PY - 1981/1/1
Y1 - 1981/1/1
N2 - Radiolabeled vitamin D sterols (5 nmol) were administered intraduodenally (in fat emulsion) into conscious rats with mesenteric lymph fistula and portal vein cannulation. The rats were kept for 4 h in restraining cages, and lymph and blood samples were collected at half-hour intervals. Vitamin D3 was absorbed mostly into the mesenteric lymph (6.5% of administered dose vs. < 1%/4 h into the portal blood). 1,25-Dihydroxyvitamin D3 was absorbed mainly into the portal blood (~7%/4 h and only 1.6%/4 h into the mesenteric lymph). 25-Hydroxyvitamin D3 had a similar rate of absorption into the lymph and portal vein (5%/4h and 7%/4 h, respectively). Vitamin D3 absorption started after 2 h, whereas the more hydroxylated metabolites were more rapidly absorbed and appeared in the lymph and portal blood within the first half-hour. In the lymph the vitamin D sterols were transported mainly on chylomicrons and lipoproteins (> 50%), whereas in blood less than 20% were associated with plasma lipoproteins. In rats where lymph was not diverted, the increment of lymphatic contribution was observed in plasma levels for all vitamin D sterols. The absorbed sterols in lymph and blood were mostly unchanged with the exception of 25-hydroxyvitamin D3, about one-third of which underwent esterification during absorption into the mesenteric lymph. We conclude that 25-hydroxyvitamin D3 and 1,25-dihydroxyvitamin D3, in particular, are absorbed directly into portal blood independent of fat absorption, and thus may be prescribed as oral supplements in most patients with fat malabsorption.
AB - Radiolabeled vitamin D sterols (5 nmol) were administered intraduodenally (in fat emulsion) into conscious rats with mesenteric lymph fistula and portal vein cannulation. The rats were kept for 4 h in restraining cages, and lymph and blood samples were collected at half-hour intervals. Vitamin D3 was absorbed mostly into the mesenteric lymph (6.5% of administered dose vs. < 1%/4 h into the portal blood). 1,25-Dihydroxyvitamin D3 was absorbed mainly into the portal blood (~7%/4 h and only 1.6%/4 h into the mesenteric lymph). 25-Hydroxyvitamin D3 had a similar rate of absorption into the lymph and portal vein (5%/4h and 7%/4 h, respectively). Vitamin D3 absorption started after 2 h, whereas the more hydroxylated metabolites were more rapidly absorbed and appeared in the lymph and portal blood within the first half-hour. In the lymph the vitamin D sterols were transported mainly on chylomicrons and lipoproteins (> 50%), whereas in blood less than 20% were associated with plasma lipoproteins. In rats where lymph was not diverted, the increment of lymphatic contribution was observed in plasma levels for all vitamin D sterols. The absorbed sterols in lymph and blood were mostly unchanged with the exception of 25-hydroxyvitamin D3, about one-third of which underwent esterification during absorption into the mesenteric lymph. We conclude that 25-hydroxyvitamin D3 and 1,25-dihydroxyvitamin D3, in particular, are absorbed directly into portal blood independent of fat absorption, and thus may be prescribed as oral supplements in most patients with fat malabsorption.
UR - http://www.scopus.com/inward/record.url?scp=0019474331&partnerID=8YFLogxK
U2 - 10.1016/0016-5085(81)90268-7
DO - 10.1016/0016-5085(81)90268-7
M3 - Article
AN - SCOPUS:0019474331
SN - 0016-5085
VL - 80
SP - 1528
EP - 1534
JO - Gastroenterology
JF - Gastroenterology
IS - 6
ER -