Tissue specific-distribution and metabolism of vitamin A are affected by dietary protein levels in rats.
The effect of dietary protein levels on tissue-specific distribution and metabolism of vitamin A was studied in rats given [15-14C] retinol (14C-ROH). The weanling rats were fed a low level vitamin A diet for 10 days, then rats (15 rats per group) were divided into 2 groups; one was given a 40% casein diet as a high protein diet (HP-diet), and the other a 5% casein diet as a low protein diet (LP-diet). After 10 days feeding on these diets, 14C-ROH (5 microCi/rat) was given to both groups, HP-diet and LP-diet, by intraperitoneal injection. The radioactivity in the exhalated gases, urine and feces was measured to estimate the rate of vitamin A metabolism. The tissue specific-distribution of ROH was studied in terms of the radioactivities of the ROH fractions separated by HPLC. The hepatic 14C-ROH content in the HP-diet group was lower than that in the LP-diet group at 24, 48, and 72 hours after administration of 14C-ROH. In contrast, 14C-ROH content in serum, spleen, pancreas, and small intestinal mucosa in the HP-diet group was higher than that in the LP-diet group. The radioactivity of the exhalated gas and feces was higher in the HP-diet group. These results suggest that metabolism of vitamin A is higher with intake of a HP-diet. Thus, dietary protein levels may affect tissue-specific distribution and metabolism of vitamin A, thereby modulating the actions of this vitamin.
Furusho
T
T
Department of Nutrition, Junior College of Agriculture, Tokyo University of Agriculture, Japan.
Wada
M
M
Yasuhara
T
T
Kataoka
E
E
Kato
S
S
Masushige
S
S
D000818:Animals; D002250:Carbon Radioisotopes / Q000378:metabolism; D004044:Dietary Proteins / Q000378:metabolism*; D005243:Feces / Q000737:chemistry; D005740:Gases / Q000378:metabolism; D008297:Male; D051381:Rats; D017208:Rats, Wistar; D014018:Tissue Distribution / Q000187:drug effects; D014556:Urine / Q000737:chemistry; D014801:Vitamin A / Q000378:metabolism / Q000493:pharmacokinetics*
D002250:Carbon Radioisotopes; D004044:Dietary Proteins; D005740:Gases; D014801:Vitamin A