Description
Citrulline level can be used as surrogate marker for estimating NO production.
L-citrulline is synthesised in the citrulline-NO-cycle when L-arginine is oxidised to citrulline by NO synthase (NOS). In the second part of the urea cycle, arginine is re-synthesised from citrulline. The NOS catalysed formation of L-citrulline and NO proceeds in two steps, whereby the product stoichiometry of L-citrulline and NO is 1:1. Thus, the conversion of L-arginine to L-citrulline can be used as a surrogate marker for the NO synthesis. Pathologic high levels of citrulline serve as an indicator of nitrosative stress.
