Original Paper Ann Nutr Metab 2004;48:90–94 DOI: 10.1159/000077043 Annals of Carnitine Supplementation Fails to Maximize Fat Mass Loss Induced by Endurance Training in Rats Marcelo Saldanha Aoki a,b André Luı´s Rodriguez Amaral Almeida a,d Francisco Navarro b,c Luı´s Fernando Bicudo Pereira Costa-Rosa a Reury Frank Pereira Bacurau b,c a Institute of Biomedical Sciences, USP, Sa ˜ o Paulo; b Laboratory Exercise Physiology – Faculty of Physical Education, UniFMU, Sa ˜ o Paulo; c Lato Sensu Post-graduate Program – University Gama Filho, Rio de Janeiro, and d Faculty of Physical Education, UniSant’Anna, Sa ˜ o Paulo, Brazil Received: March 31, 2003 Accepted: August 11, 2003 Published online: February 25, 2004 Marcelo Saldanha Aoki Institute of Biomedical Sciences I Av. Professor Lineu Prestes, 1524 s.410 University of Sa ˜o Paulo, Sa ˜o Paulo 05508-900 (Brazil) Tel./Fax +55 3091 7311, E-Mail msaoki@usp.br ABC Fax + 41 61 306 12 34 E-Mail karger@karger.ch www.karger.com © 2004 S. Karger AG, Basel 0250–6807/04/0482–0090$21.00/0 Accessible online at: www.karger.com/anm Key Words Carnitine supplementation W Endurance training W Fat mass Abstract Background/Aims: Carnitine is a co-factor of the enzy- matic system involved in long chain fatty acid transport across the mitochondrial membrane. This physiological role of carnitine raised the hypothesis that this com- pound could act as a ‘fat burner’ by optimizing fat oxida- tion and consequently reducing its availability for stor- age. Our aim was to verify whether carnitine supplemen- tation could maximize fat mass loss in trained rats. Meth- ods: Male Wistar rats (200 g) were divided into four groups: control (C), sedentary supplemented (S), trained (T) and trained supplemented (TS). The training protocol consisted of bouts of swimming exercise (60 min W day –1 ) for 6 weeks. During the last 14 days, before sacrifice, the supplemented groups received a daily dose of 28 mg W kg –1 of L-carnitine. Carcass fat content, weight and fat content of adipose tissues were evaluated in all experi- mental groups. Results: Our results indicate that carni- tine feeding, per se, failed to promote fat mass loss. Endurance training successfully induced a decrease in the fat content in the carcass (28%) and the weight of adipose tissues (retroperitoneal and mesenteric depots by 41 and 20%, respectively) in comparison to C. Despite the augmented carnitine content in the soleus mitochon- dria (2-fold) observed in TS, the higher content did not maximize the fat loss induced by endurance training. Conclusions: Our data strongly suggest that endurance training, rather than carnitine content, is the major factor involved in fat mass loss. Copyright © 2004 S. Karger AG, Basel Introduction It is well established that carnitine plays a key role in lipid metabolism. Friedman and Fraenkel [1] demon- strated that long chain fatty acid transport is a carnitine- dependent process. The rate-limiting step in the ß-oxida- tion of long chain fatty acids is assumed to be the trans- port through the mitochondrial membranes [2, 3], which is mediated by the carnitine palmitoyltransferase enzy- matic system (CPT I, carnitine-acylcarnitine translocase and CPT II) [4, 5]. The enhancement in CPT activity con- Downloaded by: Universidade de Sao Paulo - USP 143.107.252.23 - 6/15/2013 5:39:50 PM