Absorption, storage, and distribution of beta-carotene in normal and beta-carotene-fed rats: roles of parenchymal and stellate cells.
Absorption and storage of [14C]beta-carotene in control and beta-carotene-fed (BC-fed) rats were determined. Pre-feeding with beta-carotene for 2 weeks caused a 1.9-fold stimulation of its own absorption as well as its conversion to retinyl esters, whereas the absorption of [3H]retinyl acetate was unaffected. The liver and the lungs accounted for 60% and 30%, respectively, of the total recovered 14C radioactivity in both control and BC-fed groups. Beta-carotene accounted for 80-87% of the recovered 14C radioactivity in both the liver and the lung. Subcellular distribution of [14C]beta-carotene in both control and BC-fed groups revealed that the cytosol was the major fraction accounting for 44.4% and 26.8% of the radioactivity in the liver and lungs, respectively. Distribution of beta-carotene among liver parenchymal (PC) and stellate cells (STC) was determined in the two groups. Based on radioactivity, the PC and STC contained 22% and 78% of the total, respectively, in the control group; the corresponding values for the PC and STC in the BC-fed group were 48% and 52% of the total radioactivity, respectively. Based on the beta-carotene concentration following chronic beta-carotene feeding, PC contained 75.5% while the STC had 24.5% of the total beta-carotene. Thus, parenchymal cells seem to be the major hepatic storage site for dietary beta-carotene after chronic feeding.
Lakshman
M R
MR
Lipid Research Laboratory, Veterans Administration Medical Center, Washington, DC 20422.
Asher
K A
KA
Attlesey
M G
MG
Satchithanandam
S
S
Mychkovsky
I
I
Coutlakis
P J
PJ
D000042:Absorption; D000818:Animals; D002338:Carotenoids / Q000008:administration & dosage / Q000493:pharmacokinetics*; D002845:Chromatography / Q000379:methods; D002851:Chromatography, High Pressure Liquid; D002914:Chylomicrons / Q000008:administration & dosage / Q000378:metabolism; D004032:Diet; D007275:Injections, Intravenous; D007413:Intestinal Mucosa / Q000378:metabolism; D008099:Liver / Q000378:metabolism*; D008168:Lung / Q000378:metabolism; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D012176:Retinoids / Q000378:metabolism; D014018:Tissue Distribution; D019207:beta Carotene
D002914:Chylomicrons; D012176:Retinoids; D019207:beta Carotene; D002338:Carotenoids