In vivo evidence for a vitamin B-6 requirement in carnitine synthesis.
The purpose of this study was to determine whether there is a requirement for vitamin B-6 (B6) in carnitine synthesis. Rats were fed a B6-deficient (-B6) (0.04 mg pyridoxine [PN]/kg) diet (ad libitum or meal-fed) or a control (+B6) (5.7 mg PN/kg) diet (ad libitum or pair-fed). These diets were fed for 6 wk, then some of the rats were repleted with the +B6 diet for 2 wk. Total acid-soluble carnitine (TCN) and free carnitine (FCN) levels were compared in the plasma, liver, skeletal muscle, heart muscle and urine and rats fed +B6 or -B6 diets. In -B6 rats vs. +B6 rats, TCN levels were significantly lower (P less than 0.05) in the plasma, skeletal muscle, heart muscle and urine, but not in the liver. However, if rats were fasted for 3 d, liver TCN concentration of -B6 rats was significantly lower than that of +B6 rats. After B6-deficient rats were repleted with the +B6 diet, the TCN level in the plasma, liver, skeletal muscle, heart muscle and urine returned to the levels of control rats. Thus, the decrease in TCN and FCN levels with a B6-deficient diet and the increase of these levels after B6 repletion provides evidence for the B6 requirement in the biosynthesis of carnitine.
Cho
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Department of Nutrition and Food Management, Oregon State University, Corvallis 97331.
Leklem
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JE
D000704:Analysis of Variance; D000818:Animals; D001835:Body Weight; D002331:Carnitine / Q000096:biosynthesis* / Q000378:metabolism; D004032:Diet; D005215:Fasting / Q000378:metabolism; D008099:Liver / Q000378:metabolism; D008297:Male; D009132:Muscles / Q000378:metabolism; D009206:Myocardium / Q000378:metabolism; D011732:Pyridoxal Phosphate / Q000378:metabolism; D011736:Pyridoxine / Q000502:physiology*; D051381:Rats; D011919:Rats, Inbred Strains; D026681:Vitamin B 6 Deficiency / Q000378:metabolism
D011732:Pyridoxal Phosphate; D011736:Pyridoxine; D002331:Carnitine