Enterohepatic circulation of newly administered alpha-tocopherol in the rat.
We have measured the magnitude of the enterohepatic circulation of newly administered [3H]-alpha-tocopherol in rats. One group of animals (day-1 rats) was used to prepare [3H]-alpha-tocopherol-containing lymph. Another set of animals (day-2 rats) was divided into control and vitamin E supplemented (+E) groups, which were used to study the enterohepatic circulation of [3H]-alpha-tocopherol from day-1 rat lymph administered into the jugular vein of day-2 rats. Mesenteric lymph duct and common bile duct cannulations were performed. The enterohepatic circulation in day-2 rats of intrajugularly administered [3H]-alpha-tocopherol in chylomicrons was found to be 1.78 +/- 0.23% for control and 0.98 +/- 0.08% for +E rats (p less than 0.01). A considerable quantity (13.3 +/- 4.3% in control vs 19.2 +/- 4.7% in +E) of [3H]-radioactivity was recovered in bile over 24 h, of which pure [3H]-alpha-tocopherol was 3.17% in control and 1.04% in +E bile. More than 95% of [3H]-radioactivity recovered in day-2 control and +E bile was more polar than alpha-tocopherol shown by high performance liquid chromatography (HPLC). In contrast, more than 95% of [3H]-radioactivity appearing in day-2 lymph was unchanged alpha-tocopherol. Thus, the magnitude of enterohepatic circulation of alpha-tocopherol is very small in rats. Quantitation of the enterohepatic circulation of vitamin E under different physiological conditions remains to be investigated.
Lee-Kim
Y C
YC
US Department of Agriculture Human Nutrition Research Center on Aging, Tufts University, Boston, MA 02111.
Meydani
M
M
Kassarjian
Z
Z
Blumberg
J B
JB
Russell
R M
RM
D000818:Animals; D001646:Bile / Q000378:metabolism; D004764:Enterohepatic Circulation; D008099:Liver / Q000098:blood supply / Q000378:metabolism*; D008196:Lymph / Q000378:metabolism; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D014810:Vitamin E / Q000493:pharmacokinetics*
D014810:Vitamin E