Urinary excretion of NG-dimethylarginines in multiple sclerosis patients: preliminary observations

The concentrations of N G, N′ G-dimethylarginine [Me 2(sym)Arg] and N G, N G-dimethylarginine [Me 2(asym)Arg] were determined in the urine samples from multiple sclerosis (MS) and control subjects, using a highly sensitive HPLC post-column o-phthaldialdehyde derivatization method. The presence of approximately equal amounts of both dimethylarginine isomers, of Arg concentration nearly half of Me 2Arg, and of the undetectable amount of N G-monomethylarginine were the characteristic urinary excretion pattern in all human samples studied. The urinary excretion of Me 2(asym)Arg and Me 2(sym)Arg from MS ( n = 9) and control ( n = 7) were analyzed: the mean values from the samples were approximately 20% (for all MS) and 33% (for chronic-progressive MS) lower than those from the control for both dimethylarginine-derivatives when compared to the respective compounds. Although there were contrasting trends between controls and MS patients in the relationship of urinary N G-dimethylarginines and myelin basic protein like material (MBPLM), the correlations were not significant. Differences in the ratios of the concentrations of the two dimethyl derivatives, Me 2(sym)Arg Me 2(asym)Arg , were not significantly different between MS and control groups. These findings warrant further investigation of possible links between urinary excretion of N G-dimethylarginine and MBPLM in MS. The possible significance of myelin metabolism in relation to urinary N G-dimethylarginines in MS is discussed.