• Scott Blackwell, O'ReillyDenis St JDS, David Reid, and Dinesh Talwar.
• Department of Clinical Biochemistry, Royal Infirmary, Glasgow, UK.
• Eur. J. Clin. Invest. 2011 Jun 1; 41 (6): 635641635-41.

IntroductionAsymmetric dimethylarginine (ADMA) concentrations are increased in critically ill patients and may play a role in multiple organ failure. However, plasma ADMA concentrations during the development of the inflammatory response have not been documented. We measured plasma ADMA, as well as urinary excretion of its major metabolite dimethylamine, and nitrate as a marker of nitric oxide synthase (NOS) activity, in a cohort of patients undergoing elective knee arthroplasty that is known to provoke a significant inflammatory response.MethodsThirty-eight patients were recruited. Fasting venous blood samples were obtained pre-operatively and at 12h and daily until the fifth post-operative day. ADMA and symmetric dimethylarginine (SDMA) were measured by high-performance liquid chromatography (HPLC). Urinary dimethylamine and nitrate were measured pre-operatively and on each of the post-operative mornings using HPLC and expressed as a ratio to creatinine.ResultsPlasma ADMA fell by a median of 31% during the post-operative period, reaching a nadir on day 2, and recovering to baseline by the end of the study. SDMA showed no significant changes. No increase in urinary dimethylamine excretion was noted until day 5 post-op, whereupon it doubled. Urinary nitrate showed a small, but nonsignificant decrease on day 2, suggesting no major activation of NOS activity.ConclusionsPlasma ADMA concentration decreases rapidly and transiently during the first 48h of acute inflammation. This appears not be caused by increased catabolism and may reflect increased cellular partitioning. This may serve to regulate NOS activity and prevent harmful increases in inducible NOS in situations where it is not appropriate.© 2010 The Authors. European Journal of Clinical Investigation © 2010 Stichting European Society for Clinical Investigation Journal Foundation.

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