Vascular endothelial dysfunction resulting from l-arginine deficiency in a patient with lysinuric protein intolerance

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Abstract

Although L-arginine is the only substrate for nitric oxide (NO) production, no studies have yet been reported on the effect of an L-arginine deficiency on vascular function in humans. Lysinuric protein intolerance (LPI) is a rare autosomal recessive defect of dibasic amino acid transport caused by mutations in the SLC7A7 gene, resulting in an L-arginine deficiency. Vascular endothelial function was examined in an LPI patient who was shown to be a compound heterozygote for two mutations in the gene (5.3-kbp Alu-mediated deletion, IVS3+1G→Α). The lumen diameter of the brachial artery was measured in this patient and in healthy controls at rest, during reactive hyperemia (endothelium-dependent vasodilation [EDV]), and after sublingual nitroglycerin administration (endothelium-independent vasodilation [EIV]) using ultrasonography. Both EDV and NOx concentrations were markedly reduced in the patient compared with those for the controls. They became normal after an L-arginine infusion. EIV was not significantly different between the patient and controls. Positron emission tomography of the heart and a treadmill test revealed ischemic changes in the patient, which were improved by the L-arginine infusion. Thus, in the LPI patient, L-arginine deficiency caused vascular endothelial dysfunction via a decrease in NO production.

Authors

Yoshihiro Kamada, Hiroyuki Nagaretani, Shinji Tamura, Tohru Ohama, Takao Maruyama, Hisatoyo Hiraoka, Shizuya Yamashita, Akira Yamada, Shinichi Kiso, Yoshiaki Inui, Nobuyuki Ito, Yoshiro Kayanoki, Sumio Kawata, Yuji Matsuzawa