Measurement of nitric oxide-related amino acids in serum and plasma: effects of blood clotting and type of anticoagulant.

Background: Analysis of circulatory amino acids is performed in diverse fields of research, but very often without justification or even specification of specimen type. We investigated the impact of coagulation and anticoagulants on amino acid concentrations, with emphasis on amino acids involved in nitric oxide metabolism.

Methods: Plasma, using either heparin or EDTA as anticoagulant, and serum were collected from 23 apparently healthy subjects.

Hypertaurinemia in bile duct-ligated rats after surgery: the effect of gut endotoxin restriction on organ fluxes and oxidative status.

Surgery in obstructive jaundice is associated with complications related to gut-derived endotoxemia. The organs involved in these complications, including liver, kidneys, and gut, are important in the metabolism of taurine, which is implicated in bile acid conjugation and has antioxidative effects. Taurine organ metabolism and liver oxidative status were studied in bile duct-ligated rats (BDL) after laparotomy.

Determination of arginine, asymmetric dimethylarginine, and symmetric dimethylarginine in human plasma and other biological samples by high-performance liquid chromatography.

Asymmetric dimethylarginine (ADMA), an endogenous inhibitor of nitric oxide synthase (NOS), may be related to reduced biosynthesis of nitric oxide in diseases associated with accelerated atherosclerosis. The closely related compound symmetric dimethylarginine (SDMA) does not inhibit NOS, but may compete with arginine for cellular uptake, thereby limiting substrate availability for NOS. We report on a method for the simultaneous measurement of arginine, ADMA, and SDMA as a tool to gain insight in the role of these compounds in the regulation of NOS activity.