Kidney donors and kidney transplants have abnormal aminothiol redox status, and are at increased risk of oxidative stress and reduced redox buffer capacity

Abstract

Objective: Living kidney donors have been part of a successful kidney transplant programme in Norway for almost 50 years. Glomerular filtration rates (GFRs) have tended to remain stable at about 70% of pre-donation levels. Plasma total homocysteine (Hcy) has an inverse relationship to kidney function, and previous reports indicate elevated levels of Hcy in kidney donors. We wanted to examine the most important plasma aminothiols in kidney donors, i.e. Hcy, cysteine (Cys) and cysteinylglycine (CG) with their redox species. The aminothiol redox-system appears to be an integral part of the extracellular antioxidant defence system in the body.

Design and methods: Plasma concentrations of total Hcy were obtained in 82 previous kidney donors, 82 healthy controls and 26 kidney transplants with stable and good kidney function. In a subset of 30 kidney donors, 30 matched controls and 12 kidney transplants plasma samples were analysed for Hcy, Cys, CG and their redox species. There were no differences between groups for B-vitamin status.

Results: Kidney donors and kidney transplants had elevated plasma concentrations of total Hcy, Cys and CG. The plasma levels of reduced Hcy species were high - with a high reduced/oxidized ratio. The plasma levels of reduced Cys species were low - with a low reduced/oxidized ratio.

Conclusions: Previous kidney donors have abnormal plasma aminothiol redox status. The present findings indicate that donors may have increased risk of oxidative stress with low redox buffer capacity and disturbed cellular redox-dependent signalling pathways. Similar observations were made in the kidney transplants.

Keywords: Cysteine; Homocysteine; Ischaemic vascular disease; Kidney donors; Preeclampsia; Redox status.