The Role of Carnitine in Subcutaneous White Adipose Tissue from Newborn Infants

Novák, Milan; Hahn, Peter; Penn, Duna; Monkus, E.; Skala, Judith A.

doi:10.1159/000240582

Cited by 15 publications

(14 citation statements)

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“…They can be used to label the pool of intracellular fatty acids permitting the measurement of changes in oxidation and esterification rate (14). The observation that carnitine increases the oxidation of [14C]palmitate in adipocytes isolated from human newborn adipose tissue (Table 1) again confirms the presence of a carnitine-dependent pathway for fatty acid oxidation as suggested by earlier results showing that carnitine increased oxygen consumption in isolated cells (20) and mitochondria (19) from newborn adipose tissue.…”

Section: Discussionsupporting

confidence: 84%

“…1 and 2). A s previously reported, the carnitine palmitoyltransferase activity in mitochondria isolated from the adipose tissue of newborns older than 1 day of age is higher than in those from the white adipose tissue of adults (20). However, lower values observed shortly after birth, as well as in four premature newborns (Fig.…”

Section: Discussionsupporting

confidence: 53%

“…Two different methods were used to determine CPT activity: In method A , the activity of CPT was assayed colorimetrically as described earlier (20) by measuring the reaction of DTNB with CoA released from palmitoyl CoA. For method B the method of Bremer (3) was modified as follows.…”

Section: Resultsmentioning

confidence: 99%

“…In some respect, the small polyvacuolar cells morphologically and metabolically resemble brown adipose tissue (19). Mitochondria isolated from these cells exhibit carnitine-dependent fatty acid oxidation, whereas mitochondria from the larger univacuolar cells, like those from adipocytes of adult white adipose tissue, do not increase oxygen consumption after addition of carnitine (19,20). Carnitine elevates lipolysis in newborn adipose tissue fragments or isolated fat cells, but has no effect on adult tissue unless a lipolytic agent is present (27).…”

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Carnitine and Development of Newborn Adipose Tissue

et al. 1978

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Section: Discussionsupporting

confidence: 84%

Section: Discussionsupporting

confidence: 53%

Section: Resultsmentioning

confidence: 99%

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Carnitine and Development of Newborn Adipose Tissue

et al. 1978

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“…In man, carnitine palmitoyl transferase activity in white fat also rises rapidly after birth (27,35).…”

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Acetylcarnitine and Free Carnitine in Body Fluids before and after Birth

et al. 1979

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SummaryThe acetylcarnitine concentration in amniotic fluid fell significantly between 33 and 37 and 40 weeks of gestation. It was significantly higher in samples that had a low lecithin to sphingomyelin ratio. The acetylcarnitine content of tracheal fluid was higher in samples obtained from premature newborns. The major excretory form of carnitine is the acetate ester and only in adults does the urine contain significant amounts of free carnitine. The level of acetylcarnitine in plasma significantly increases after the first day of life; there was no difference in the plasma levels of carnitine between full-term and premature newborns. Plasma-free carnitine and acetylcarnitine levels were significantly lower in infants who were receiving a soybean-based formula. A positive correlation was found between the plasma level of ketone bodies and that of acetylcarnitine. SpeculationA characteristic of early postnatal adaptation in human newborns is a high dependence on the utilization of fatty acids derived from endogenous sources and increasingly from digested milk triglycerides. This essential energy-producing mechanism seems to be facilitated by carnitine, of which a considerable amount is derived from m a .It is well known that the change from fetal life to extrauterine existence entails, among other things, changes in the supply and utilization of nutriknts. In mammals, including humans, the "prenatal diet" can be considered as one high in carbohydrate, postnatally as a high-fat diet (1, 18). This change is accompanied by a rapid m e in blood levels of free fatty acids and ketone bodies after birth (26,28,38). This rapid elevation of free fatty acid blood levels in human newborns during or shortly after birth is due to the release of fatty acids from adipose tissue mainly in response to j? adrenergic stimulation of lipolysis (29,39). Later high levels of free fatty acid in blood reflect intestinal absorption of fatty acids from triglycerides supplied in the diet (18). Thus, / 3 oxidation of free fatty acid would seem to be a very important source of energy in the newborn. Carnitine (y-trimethylamino-P-hydroxybutyrate) is essential for optimum oxidation of fatty acids in mitochondria (2), since it facilitates transport of fatty acid across the mitochondrial membrane:There is no doubt that carnitine and the carnitine transferases are essential for fatty acid oxidation after birth. We have reported relatively constant individual levels of free carnitine after birth in whole blood (35). However, there is substantial carnitine excretion in urine (35) before onset of feeding. Intake of exogenous carnitine 1 varies with the type of milk fed. Formulas with a soybean base have no detectable carnitine (35).The rapid postnatal increase in fat utilization in the rat is accompanied by a rise in hepatic (2, 3), cardiac (42, 43), brain (19), and brown fat (19) carnitine palmitoyl transferase and carnitine acetyl transferase activities. In man, carnitine palmitoyl transferase activity in white fat also rises rapidly after birth (...

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Carbohydrate, Fat, and Amino Acid Metabolism in the Pregnant Woman and Fetus

Adam

Felig

1978

Principles and Prenatal Growth

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The Role of Carnitine in Subcutaneous White Adipose Tissue from Newborn Infants

Cited by 15 publications

References 10 publications

Carnitine and Development of Newborn Adipose Tissue

Carnitine and Development of Newborn Adipose Tissue

Acetylcarnitine and Free Carnitine in Body Fluids before and after Birth

Carbohydrate, Fat, and Amino Acid Metabolism in the Pregnant Woman and Fetus

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