L-arginine supplementation improves exercise capacity after a heart transplant.
BACKGROUND
Endothelial dysfunction is associated with the decreased exercise capacity observed in heart-transplant (HTx) recipients. L-arginine supplementation (LAS) stimulates the nitric oxide (NO) pathway and restores endothelial function.


OBJECTIVE
We compared exercise capacity in healthy subjects and HTx patients and investigated whether chronic LAS might improve exercise capacity and NO/endothelin balance after an HTx.


METHODS
Clinical, echocardiographic, and exercise characteristics were measured in 11 control subjects and 22 HTx recipients. In a prospective, double-blind study, the 22 HTx recipients performed a 6-min exercise [6-min-walk test (6MWT)] and a maximal bicycle exercise test before and after a 6-wk period of placebo intake or LAS. Endothelial function was measured by analyzing blood NO metabolites, endothelin, and the resulting NO/endothelin balance.


RESULTS
Exercise capacity decreased after transplantation. Unlike with the placebo intake, 6 wk of LAS improved quality of life in HTx recipients (mean +/- SEM Minnesota Score: from 15.3 +/- 1.3 to 10.6 +/- 1.1; P < 0.001) and their submaximal exercise capacity. The distance walked during the 6MWT increased (from 525 +/- 20 to 580 +/- 20 m; P = 0.002), and the ventilatory threshold during the incremental test was delayed by 1.2 min (P = 0.01). Central factors such as resting stroke volume, systolic pulmonary arterial pressure, cardiac systolodiastolic functions, and heart-rate reserve were not modified, but LAS significantly increased the NO:endothelin ratio (from 2.49 +/- 0.38 to 3.31 +/- 0.39; P = 0.03).


CONCLUSIONS
Oral LAS may be a useful adjuvant therapeutic to improve quality of life and exercise tolerance in HTx recipients.
Doutreleau
Stéphane
S
Medicine Faculty, Physiology Institute, Strasbourg, France. stephane.doutreleau@chru-strasbourg.fr
Rouyer
Olivier
O
Di Marco
Paola
P
Lonsdorfer
Evelyne
E
Richard
Ruddy
R
Piquard
François
F
Geny
Bernard
B
D001120:Arginine / Q000008:administration & dosage / Q000097:blood / Q000627:therapeutic use*; D001794:Blood Pressure / Q000187:drug effects; D016572:Cyclosporine / Q000097:blood; D019587:Dietary Supplements; D004311:Double-Blind Method; D004452:Echocardiography; D019332:Endothelin-1 / Q000097:blood; D016232:Endothelins / Q000097:blood; D005080:Exercise Test / Q000379:methods; D017079:Exercise Tolerance / Q000502:physiology*; D006339:Heart Rate / Q000187:drug effects; D016027:Heart Transplantation / Q000502:physiology*; D006801:Humans; D007166:Immunosuppressive Agents / Q000097:blood / Q000627:therapeutic use; D008875:Middle Aged; D009569:Nitric Oxide / Q000097:blood; D018579:Patient Selection; D010919:Placebos; D011651:Pulmonary Artery / Q000187:drug effects / Q000502:physiology / Q000503:physiopathology; D011788:Quality of Life
D019332:Endothelin-1; D016232:Endothelins; D007166:Immunosuppressive Agents; D010919:Placebos; D009569:Nitric Oxide; D016572:Cyclosporine; D001120:Arginine