The purpose of this study was, first, to investigate whether there
is a vitamin B-6 requirement for carnitine synthesis and, second, to investigate
the effect of fasting on vitamin B-6 metabolism. An experimental
group of 72 rats (6 per group) were fed either a vitamin B-6 deficient
diet (-B6) (ad libitum, meal-fed) or a control diet (+B6) (ad libitum,
pair-fed). These diets were fed for 6 weeks and then the rats were repleted
with the control diet for 2 weeks. The animals were fasted for 3
days before and after repletion. Total acid soluble carnitine (TCN) and
free carnitine (FCN) levels were compared in the plasma, liver, skeletal
muscle, heart muscle and in the urine of rats fed +B6 diet and -B6 diets.
The concentrations of pyridoxal 5'-phosphate (PLP) in the plasma, liver,
skeletal muscle, and heart muscle and urinary 4-pyridoxic acid (4-PA) excretion
were compared in rats fed the +B6 or -B6 diet. Similar comparisons
were made in fasted and non-fasted rats. Also, plasma glucose, liver
glycogen, and free fatty acid concentrations were compared.
In rats fed the -B6 vs +B6 diet, the TCN concentration was significantly
(P < 0.05) lower in the plasma, skeletal muscle, heart muscle and
urine. With fasting, the liver TCN concentration of -B6 rats was also
significantly lower than that of +B6 rats. After the -B6 rats were repleted
with the +B6 diet, the TCN concentrations in the plasma, liver,
skeletal muscle, heart muscle, and urine returned to those of the control
rats. Thus, the decrease in TCN and FCN concentrations, and the increase
of these concentrations after repletion provides evidence for a
vitamin B-6 requirement in the biosynthesis of carnitine.
Fasting resulted in increased concentrations of PLP in the plasma,
liver, and heart muscle of rats fed a -B6 diet. The urinary 4-PA excretion
of -B6 rats also increased with fasting. These changes are consistent
with a redistribution of vitamin B-6 (as PLP) when there is a caloric
deficit. Thus, with fasting, PLP is supplied by an endogenous source,
possibly skeletal muscle glycogen phosphorylase. In -B6 vs +B6 rats, liver
glycogen concentration was higher and plasma FFA concentration was lower. / Graduation date: 1987
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/27287 |
| Date | 05 May 1987 |
| Creators | Cho, Youn-ok |
| Contributors | Leklem, James E. |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
Page generated in 0.0018 seconds