Carnitine concentration during the development of human tissues

Nakano, C; Takashima, Sachio; Takeshita, Kenzo

doi:10.1016/0378-3782(89)90101-1

Cited by 36 publications

(33 citation statements)

References 8 publications

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“…Data obtained from autopsy samples [5,6] support the view that in infants and children carnitine from the diet represents a major source for maintain ing normal carnitine levels in plasma and probably in most tissues.…”

supporting

confidence: 51%

Carnitine Supplementation in Soy-Based Formula-Fed Infants

Novák

1990

Neonatology

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Gradual increase of carnitine in plasma, tissues and urine after birth is a normal response of breast-fed infants and those receiving carnitine-containing formulas. Marked reduction of carnitine and acylcarnitines was noted in infants given diets not containing carnitine. These differences promted the evaluation of the rationale for adding carnitine into soy-based formulas. In healthy term infants the lack of dietary carnitine did not induce deficiency symptoms but reduced the uptake of fatty acids for β-oxidation. The cumulative effect of various metabolic disorders and carnitine deficient diets may culminate to carnitine deficiency.

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supporting

confidence: 51%

Carnitine Supplementation in Soy-Based Formula-Fed Infants

Novák

1990

Neonatology

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“…Carnitine tissue stores of newborn in fants under 24 h of age have been measured by Shenai and Borum [16] and our group [17], There is a positive correlation between muscle carnitine content and gestational age, a finding that has recently been con firmed [18], We have calculated that the skeletal muscle carnitine pool of the adult is about 4 times larger than that of the term neonate and 10 times larger than that of the very premature infant on a per kilogram body weight basis [17]. This indicates that the newborn infant, especially the prema ture, is born with limited carnine reserves, which may put him at risk to develop carni tine deficiency if exogenous carnitine is not provided through nutrition.…”

Section: Carnitine Tissue Storesmentioning

confidence: 85%

Carnitine and Total Parenteral Nutrition of the Neonate

Schmidt-Sommerfeld

Penn²

1990

Neonatology

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The newborn is dependent upon fat for energy production. Fatty acid oxidation requires the cofactor carnitine. The preterm infant is born with limited carnitine reserves. During total parenteral nutrition (TPN) plasma and tissue carnitine concentrations decrease indicating that rates of carnitine biosynthesis are inadequate. The ability of the premature infant to oxidize fatty acids is related to the carnitine status. Several studies suggest an improvement of fatty acid oxidation after a fat challenge if TPN is supplemented with L-carnitine. Nitrogen balance may also be improved but this needs confirmation. It remains to be established whether routine L-carnitine supplementation is needed in neonatal TPN.

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“…For this process, carnitine is an essential cofactor because it facilitates the transport of long-chain fatty acids across the inner mitochondrial membrane (Bremer, 1983). For this reason and because of the limited capacity especially of the early fetus for carnitine biosynthesis, transplacental carnitine transport is essential for the fetal organism and after that for the first days after delivery (Nakano et al, 1989). Because of the described function and localization of OCTN2, this transporter can play an important role in transplacental carnitine transport.…”

Section: Discussionmentioning

confidence: 99%

Expression, Localization, and Function of the Carnitine Transporter Octn2 (Slc22a5) in Human Placenta

Grube¹,

Schwabedissen²,

Draber³

et al. 2004

Drug Metab Dispos

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ABSTRACT:L-carnitine is assumed to play an important role in fetal development, and there is evidence that carnitine is transported across the placenta. The protein involved in this transfer, however, has not been identified on a molecular level. We therefore characterized localization and function of the carnitine transporter OCTN2 in human placenta. Significant expression of OCTN2 mRNA was detected in human placenta applying real-time polymerase chain reaction technology. Confocal immunofluorescence microscopy using an antibody directed against the carboxy terminus of OCTN2 protein revealed that it is predominantly expressed in the apical membrane of syncytiotrophoblasts. This was confirmed by the costaining of organic anion-transporting polypeptide B and MRP2, which are known to be expressed mainly in the basal and apical syncytiotrophoblasts membrane, respectively. To further support this finding, we performed transport studies using basal and apical placenta membrane vesicles. We could demonstrate that the carnitine uptake into the apical vesicles was about eight times higher compared with the basal ones. Moreover, this uptake was sodiumand pH-dependent with an apparent K m value of 21 M and inhibited by verapamil, which is in line with published data for recombinant OCTN2. Finally, experiments using trophoblasts in cell culture revealed that expression of OCTN2 paralleled human choriogonadotropin production and thus is modulated by cellular differentiation. In summary, we show expression and function of OCTN2 in human placenta. Moreover, several lines of evidence indicate that OCTN2 is localized in the apical membrane of syncytiotrophoblasts, thereby suggesting a major role in the uptake of carnitine during fetal development.Carnitine plays an important physiological role, in particular, in ␤-oxidation because it facilitates long-chain fatty acid transport across the inner mitochondrial membrane. Moreover, carnitine is involved in intracellular coenzyme A homeostasis and functions as an antioxidant (Bremer, 1983;Arduini et al., 1992;Pons and De Vivo, 1995). Only a few organs like brain, liver, and kidney have the ability to biosynthesize carnitine (Bremer, 1983), whereas other tissues like skeletal and heart muscles, where ␤-oxidation plays a major role in energy metabolism, are highly dependent on active carnitine uptake from blood to maintain their carnitine steady-state concentration (Siliprandi et al., 1989).Recent studies describe the organic cation transporter novel type II (OCTN2) as a high affinity uptake system for carnitine. The OCTN2 cDNA codes for 557 amino acids consisting of 12 putative transmembrane domains with a predicted molecular mass of 63 kDa . The transport of carnitine is sodium-dependent (Tamai et al., 1998), whereas other compounds such as tetraethylammonium are transported by OCTN2 in a sodium-independent way (Ohashi et al., 2001).Besides its physiological function, OCTN2 is of pharmacological relevance. Drugs like verapamil, pyrilamine, and ␤-lactam antibiotics have been characte...

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Carnitine concentration during the development of human tissues

Cited by 36 publications

References 8 publications

Carnitine Supplementation in Soy-Based Formula-Fed Infants

Carnitine Supplementation in Soy-Based Formula-Fed Infants

Carnitine and Total Parenteral Nutrition of the Neonate

Expression, Localization, and Function of the Carnitine Transporter Octn2 (Slc22a5) in Human Placenta

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