Carnitine

Borum, Peggy R.

doi:10.1146/annurev.nu.03.070183.001313

Cited by 210 publications

(97 citation statements)

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“…The patient, weighing 73 kg, selected a palatable diet, normal for him, and adhered to the same menu for 7 d. The diet was free of meat and, therefore, essentially devoid of creatine and creatinine and very low in N-methylhistidines (37) and carnitine (38). It contained 3,014 calories, 87.7 g of protein, 11.2 mmol methionine, 9.3 mg-atom cystine sulfur, and 3.6 mmol choline.…”

Section: Resultsmentioning

confidence: 99%

Transsulfuration in an adult with hepatic methionine adenosyltransferase deficiency.

Gahl¹,

Bernardini²,

Finkelstein³

et al. 1988

J. Clin. Invest.

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We investigated sulfur and methyl group metabolism in a 31-yr-old man with partial hepatic methionine adenosyltransferase (MAT) deficiency. The patient's cultured fibroblasts and erythrocytes had normal MAT activity. Hepatic S-adenosylmethionine (SAM) was slightly decreased. This clinically normal individual lives with a 20-30-fold elevation of plasma methionine (0.72 mM). He excretes in his urine methionine and L-methionine-d-sulfoxide (2.7 mmol/d), a mixed disulfide of methanethiol and a thiol bound to an unidentified group X, which we abbreviate CH3S-SX (2.1 mmol/d), and smaller quantities of 4-methylthio-2-oxobutyrate and 3-methylthiopropionate. His breath contains 17-fold normal concentrations of dimethylsulfide. He converts only 6-7 mmol/d of methionine sulfur to inorganic sulfate. This abnormally low rate is due not to a decreased flux through the primarily defective enzyme, MAT, since SAM is produced at an essentially normal rate of 18 mmol/d, but rather to a rate of homocysteine methylation which is abnormally high in the face of the very elevated methionine concentrations demonstrated in this patient. These findings support the view that SAM (which is marginally low in this patient) is an important regulator that helps to determine the partitioning of homocysteine between degradation via cystathionine and conservation by reformation of methionine. In addition, these studies demonstrate that the methionine transamination pathway operates in the presence of an elevated body load of that amino acid in human beings, but is not sufficient to maintain methionine levels in a normal range.

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Section: Resultsmentioning

confidence: 99%

Transsulfuration in an adult with hepatic methionine adenosyltransferase deficiency.

Gahl¹,

Bernardini²,

Finkelstein³

et al. 1988

J. Clin. Invest.

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“…For example, carnitine is the requisite carrier for the transport of long-chain fatty acids across the inner mitochondrial membrane into the mitochondrial matrix [7]. In muscle, carnitine concentration decreases with advancing age [8][9][10].…”

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confidence: 99%

Carnitine and Dehydroepiandrosterone Sulfate Induce Protein Synthesis in Porcine Primary Osteoblast-Like Cells

et al. 1999

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Abstract. Age-related bone loss eventually leads to osteopenia in men and women. The etiology of age-related bone loss is currently unknown; however, decreased osteoblast activity contributes to this phenomenon. In turn, osteoblast proliferation and function is dependent on energy production, thus the loss of energy production that occurs with age may account for the deficient osteoblast activity. Carnitine and dehydroepiandrosterone-sulfate (DHEAS), both of which decline with age, promote energy production through fatty acid metabolism. Thus, we hypothesized that carnitine and DHEAS would increase osteoblast activity in vitro. Accordingly, we measured the effect of carnitine and DHEAS on palmitic acid oxidation as a measure of energy production, and alkaline phosphatase (ALP) activity and collagen type I (COL) as indices of osteoblast function in primary porcine osteoblast-like cell cultures. Carnitine (10 −3 and 10 −1 M) but not DHEAS (10 −9 , 10 −8 , and 10 −7 M) increased carnitine levels within the cells. Carnitine alone and in combination with DHEAS increased palmitic acid oxidation. Both carnitine and DHEAS alone and in an additive fashion increased ALP activity and COL levels. These results demonstrate that in osteoblast-like cells in vitro, energy production can be increased by carnitine and osteoblast protein production can be increased by both carnitine and DHEAS. These data suggest that carnitine and DHEAS supplementation in the elderly may stimulate osteoblast activity and decrease age-related bone loss. Key words:Osteoblast -Carnitine -Dehydroepiandrosterone sulfate -Alkaline phosphatase -Collagen Type I.Bone loss is often divided into two broad mechanisms: (1) postmenopausal bone loss, characterized by increased osteoclast activity, and (2) age-related bone loss, characterized by decreased osteoblast activity. Osteoblast activity is dependent on energy production. Thus, it is plausible that the loss of energy production, which accompanies age, may account for decreased osteoblast activity. Most cells use both glucose and fatty acid oxidation pathways for ATP synthesis, although some cell types show a substrate preference. For instance, some studies have suggested that glucose is the major fuel substrate for bone [1,2]. However, more recent work indicates that cell populations enriched with osteoblast-like cells generate 40-80% of the energy demands through fatty acid oxidation [3]. Osteoblasts are responsible for bone formation and it follows that they maintain a high rate of ATP utilization to support the requisite protein synthesis. Cells with a high rate of protein synthesis generate ATP from fatty acid oxidation, the most efficient metabolic process for energy production [4][5][6]. Thus, modulation of fatty acid oxidation may regulate the amount of energy available for protein synthesis in osteoblasts.A number of factors are required for fatty acid oxidation. For example, carnitine is the requisite carrier for the transport of long-chain fatty acids across the inner mitochondrial membrane into...

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“…Hoffman et al (1993) reported no improvement in energy utilisation in neonatal and young pigs fed L-carnitine. However, previous studies (Broquist, 1982;Borum, 1983;Bremer, 1983;Rebouche and Paulson, 1986), showed that added L-carnitine improved fat utilisation, especially fatty acids in (3-oxidation in mammals. Also Cho et al (1999a) reported that L-carnitine improved the crude fat and gross energy digestibility in starter piglets.…”

Section: Nutrien T Digeslibuitymentioning

confidence: 94%

Effects of chromium picolinate, L-carnitine and thyroxine on the performance, nutrient digestibility and nitrogen balance in pigs weaned at 21 days of age

Cho¹,

Han²,

Chae³

et al. 2000

J. Anim. Feed Sci.

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A 3-week-growth trial was conducted to investigate the effects of chromium picolinate, L-carnitine, and thyroxine on the growth performance, nutrient digestibility, and N balance in starter pigs. Eighty starter pigs (Landrace x Yorkshire x Duroc, 21 ±2 days of age, 5.4 kg of average initial body weight) were employed in a completely randomized block design with four treatments: 1. Control: without additives, 2. CrP: control diet + 0.05% of chromium picolinate, 3. Carnitine: control diet + 0.5% of Camifeed(10%> of carnitine), 4. Thyroxine: control diet + L-thyroxine injection (0.1 mg/day/ head), 5 replications and 4 heads per pen. Although there were no significant differences (P>0.05) in average daily gain (ADG) and average daily feed intake (ADFI), all of the pigs supplemented with CrP, L-carnitine and thyroxine grew better than pigs in the control group. Pigs fed L-carnitine showed the best ADG (15% of improvement compared with control group) through the entire experimental period and feed/gain ratio was improved (PO.05). Digestibilities of energy, dry matter, crude protein and crude ash were improved (P<0.05) by the inclusion of L-carnitine, chromium picolinate or injection of thyroxine. Pigs fed chromium picolinate showed the best nutrient digestibilities. In a N balance trial, excreted N was lower (PO.05) in pigs of all treated groups than in the control group. The N in feed also was more efficiently retained in pigs of treated groups. The DNA content of the liver

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Carnitine

Cited by 210 publications

References 0 publications

Transsulfuration in an adult with hepatic methionine adenosyltransferase deficiency.

Transsulfuration in an adult with hepatic methionine adenosyltransferase deficiency.

Carnitine and Dehydroepiandrosterone Sulfate Induce Protein Synthesis in Porcine Primary Osteoblast-Like Cells

Effects of chromium picolinate, L-carnitine and thyroxine on the performance, nutrient digestibility and nitrogen balance in pigs weaned at 21 days of age

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