The Effect of Arginine and Citrulline Supplementation on Endothelial Dysfunction in Mitochondrial Diseases

Mitochondrial diseases occur due to inadequate energy production. In addition, nitric oxide (NO) deficiency occurs in mitochondrial diseases. The endothelial layer of blood vessels functions in maintaining blood vessels patency through producing NO which relaxes vascular smooth muscles and therefore maintains the patency of blood vessels and adequate blood perfusion. In mitochondrial diseases, endothelial cells fail to perform their normal function in maintaining the patency of blood vessels (endothelial dysfunction) because of the inability to produce enough NO. Endothelial dysfunction results in decreased blood perfusion in different organs which can contribute to the complications seen in mitochondrial diseases. The amino acids arginine and citrulline act as NO precursors and can increase NO production. In this study we hypothesize that due to the inability to produce enough NO patients with mitochondrial diseases have endothelial dysfunction that will improve after arginine or citrulline supplementation. The investigators will assess endothelial function using peripheral arterial tonometry before and after arginine or citrulline supplementation. The investigators expect that arginine and citrulline supplementation will improve endothelium function. This will support the therapeutic use of arginine and citrulline in mitochondrial diseases.