Source: Neuropsychologia  |  Posted 8 years ago

The acute administration of vitamin C reduces oxidant stress in renal failure, and improves nitric oxide-mediated resistance-vessel dilatation.

These were the findings of a study of 33 pre-dialysis and 17 haemodialysis patients, investigating the effect of vitamin C on endothelium-dependant responses in both the conduit and resistance vasculature in severe renal impairment.

Pre-dialysis patients received vitamin C by intra-arterial infusion (25 mg/min) and haemodialysis patients received intravenous infusion (3g).

The parenteral administration of vitamin C resulted in a 100-fold increase (intra-arterial studies) and a 4.5 fold increase (intravenous studies) in serum antioxidant activity. In addition, vitamin C was found to increase the dilator response to acetylcholine in resistance vessels, but did not alter the dilator response to flow in conduit vessels of either dialysis or pre-dialysis subjects.

The investigators reported that there was not, in the presence of the nitric oxide synthase inhibitor NGmonomethyl-1-argine (L-NMMA), any effect of vitamin C on resistance vessel endothelial function. Vitamin C did not appear to have any affect on the dilator response to the endothelium-independent dilators.