Document Detail

Effects of acute hypercarnitinemia during increased fatty substrate oxidation in man.
MedLine Citation:
PMID:  8492714     Owner:  NLM     Status:  MEDLINE    
To test whether carnitine availability is rate-limiting for fat oxidation under conditions of augmented oxidative use of fatty substrates, two series of studies were performed. In study no. 1, L-carnitine (1 g + 0.5 g/h intravenously [i.v.]) or saline was given to eight volunteers during a 4-hour infusion of a 10% triglyceride emulsion, thereby increasing plasma free-carnitine levels from 38 +/- 4 to 415 +/- 55 mumol/L. Fat infusion increased plasma triglyceride levels (80%) and lipid oxidation (30%), and decreased (28%) carbohydrate oxidation (as measured by indirect calorimetry); hypercarnitinemia had no influence on these responses. In study no. 2 in 12 healthy subjects a bolus of L-carnitine (3 g) or saline was administered 40 minutes before aerobic exercise (bicycling for 40 minutes at 60 W), followed by 2 minutes of anaerobic exercise (250 W) and 50 minutes of recovery. Oxygen consumption (VO2), increased to 18.3 +/- 0.7 mL.min-1 x kg-1 during aerobic exercise, reached a maximum of 46.0 +/- 0.8 mL.min-1 x kg-1 during the anaerobic bout, and returned to baseline within a few minutes, with no difference between control and carnitine. At virtually identical mean energy expenditure rates (196 +/- 7 v 197 +/- 7 J.min-1 x kg-1, saline v carnitine), after carnitine administration the entire exercise protocol was sustained by a lower mean carbohydrate oxidation rate (42.1 +/- 3.6 v 36.5 +/- 2.3 mumol.min-1 x kg-1, P < .03) and a higher mean lipid oxidation rate (6.7 +/- 1.0 v 8.3 +/- 0.7 mumol.min-1 x kg-1, P < .05).(ABSTRACT TRUNCATED AT 250 WORDS)
A Natali; D Santoro; L S Brandi; D Faraggiana; D Ciociaro; N Pecori; G Buzzigoli; E Ferrannini
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Metabolism: clinical and experimental     Volume:  42     ISSN:  0026-0495     ISO Abbreviation:  Metab. Clin. Exp.     Publication Date:  1993 May 
Date Detail:
Created Date:  1993-06-15     Completed Date:  1993-06-15     Revised Date:  2005-11-17    
Medline Journal Info:
Nlm Unique ID:  0375267     Medline TA:  Metabolism     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  594-600     Citation Subset:  IM    
Metabolism Unit, C.N.R. (Consiglio Nazionale delle Ricerche) Institute of Clinical Physiology, Pisa, Italy.
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MeSH Terms
Blood / metabolism
Carnitine / blood*
Fat Emulsions, Intravenous / pharmacology
Heart Rate
Infusions, Intravenous
Lipid Metabolism*
Pulmonary Gas Exchange
Time Factors
Reg. No./Substance:
0/Fat Emulsions, Intravenous; 541-15-1/Carnitine

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