Effects of L-carnitine on oxidative stress responses in patients with renal disease.
OBJECTIVE
Hemodialyzed patients demonstrate elevated oxidative stress and reduced functional status. Exercise induces health benefits, but acute exertion up-regulates oxidative stress responses in patients undergoing hemodialysis. Therefore, the aim of the present study was to examine the effect of L-carnitine supplementation on i) exercise performance and ii) blood redox status both at rest and after exercise.


METHODS
Twelve hemodialysis patients received either L-carnitine (20 mg kg(-1) i.v.) or placebo in a double-blind, placebo-controlled, counterbalanced, and crossover design for 8 wk. Participants performed an exercise test to exhaustion before and after supplementation. During the test, V˙O2, respiratory quotient, heart rate, and time to exhaustion were monitored. Blood samples, collected before and after exercise, were analyzed for lactate, malondialdehyde, protein carbonyls, reduced and oxidized glutathione, antioxidant capacity, catalase, and glutathione peroxidase activity.


RESULTS
Blood carnitine increased by L-carnitine supplementation proportionately at rest and after exercise. L-carnitine supplementation increased time to fatigue (22%) and decreased postexercise lactate (37%), submaximal heart rate, and respiratory quotient but did not affect V˙O2peak. L-carnitine supplementation increased reduced/oxidized glutathione (2.7-fold at rest, 4-fold postexercise) and glutathione peroxidase activity (4.5% at rest, 10% postexercise) and decreased malondialdehyde (19% at rest and postexercise) and protein carbonyl (27% at rest, 40% postexercise) concentration.


CONCLUSIONS
Data suggest that a 2-month L-carnitine supplementation may be effective in attenuating oxidative stress responses, enhancing antioxidant status, and improving performance of patients with end-stage renal disease.
Fatouros
Ioannis G
IG
Department of Physical Education and Sport Science, Democritus University of Thrace, Komotini, Greece.
Douroudos
Ioannis
I
Panagoutsos
Stylianos
S
Pasadakis
Ploumis
P
Nikolaidis
Michalis G
MG
Chatzinikolaou
Athanasios
A
Sovatzidis
Apostolos
A
Michailidis
Yiannis
Y
Jamurtas
Athanasios Z
AZ
Mandalidis
Dimitrios
D
Taxildaris
Kyriakos
K
Vargemezis
Vassilios
V
D000975:Antioxidants; D002331:Carnitine / Q000008:administration & dosage*; D002374:Catalase / Q000097:blood; D019587:Dietary Supplements; D015444:Exercise / Q000502:physiology; D005221:Fatigue / Q000188:drug therapy / Q000503:physiopathology; D005978:Glutathione / Q000097:blood; D005979:Glutathione Peroxidase / Q000097:blood; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D007676:Kidney Failure, Chronic / Q000503:physiopathology*; D019344:Lactic Acid / Q000097:blood; D008297:Male; D008315:Malondialdehyde / Q000097:blood; D008875:Middle Aged; D018384:Oxidative Stress / Q000187:drug effects*; D010101:Oxygen Consumption / Q000502:physiology; D050050:Protein Carbonylation / Q000187:drug effects; D006435:Renal Dialysis; D014803:Vitamin B Complex / Q000097:blood / Q000494:pharmacology
D000975:Antioxidants; D014803:Vitamin B Complex; D019344:Lactic Acid; D008315:Malondialdehyde; D002374:Catalase; D005979:Glutathione Peroxidase; D005978:Glutathione; D002331:Carnitine