Contribution of a high dose of L-ascorbic acid to carnitine synthesis in guinea pigs fed high-fat diets.
Ascorbate is a cofactor of two-enzyme hydroxylation in the pathway of carnitine biosynthesis. The purpose of this study was to investigate the contribution of ascorbate to endogenous carnitine in guinea pigs fed high-fat diets. The contents of carnitine in plasma, urine and tissues of guinea pigs supplemented with L-ascorbic acid were determined and compared with those supplemented with carnitine. Albino-Hartley guinea pigs were fed vitamin C-deficient diets containing lard throughout the experiment. They were administered orally with 5 mg L-ascorbic acid/d/animal for 14 d, and then divided into three groups and administered orally with the following supplements (/d/animal) for 14 d; L (5 mg L-ascorbic acid), LASA (100 mg L-ascorbic acid), and LCAR (10 mg carnitine plus 5 mg L-ascorbic acid). As a control, a normal group was fed vitamin C-deficient diets and administered orally with 5 mg L-ascorbic acid/d/animal for 28 d. The animals fed high-fat diets (L group) had higher free-carnitine contents in the muscle and urine than the normal group. The groups of LCAR and LASA had significantly higher contents of acid-soluble carnitine (p < 0.05) in plasma than the L group. Urinary excretion of carnitine in the LASA group was decreased to the same level as that in the normal group, although no significant difference between the groups of L and LCAR was observed. Moreover, the supplement of ascorbic acid, but not of carnitine, induced a significantly lower content of triacylglycerol in the plasma of the LASA group as compared to the L group (p < 0.05). These data suggest that high doses of ascorbic acid in guinea pigs fed high-fat diets contribute to the enhancement of carnitine synthesis and improvement of the triacylglycerol content in the plasma.
Otsuka
M
M
Department of Nutrition & Food Science, Ochanomizu University, Tokyo, Japan. m220@cc.ocha.ac.jp
Matsuzawa
M
M
Ha
T Y
TY
Arakawa
N
N
D000818:Animals; D001205:Ascorbic Acid / Q000008:administration & dosage / Q000378:metabolism*; D002331:Carnitine / Q000096:biosynthesis* / Q000097:blood / Q000652:urine; D002851:Chromatography, High Pressure Liquid; D004041:Dietary Fats / Q000008:administration & dosage / Q000378:metabolism*; D006168:Guinea Pigs; D008099:Liver / Q000737:chemistry; D008297:Male; D009132:Muscles / Q000737:chemistry; D014280:Triglycerides / Q000097:blood
D004041:Dietary Fats; D014280:Triglycerides; D001205:Ascorbic Acid; D002331:Carnitine