Discussion of Sessions 1 and 2 at the 3rd Amino Acid Assessment Workshop (3rd AAAW)

Cynober: This discussion section deals primarily with this question: which model for which amino acid? To start the discussion, I would like to ask a question to Vicky Baracos. In the figure you showed us about the extraction of amino acids by portal-drain viscera, I noticed that there was no consumption of arginine and no production of citrulline in your piglet model. What is the reason for this? Is it related to enzyme immaturity? Based on Bachier and co-workers’ studies, it seems that there is an adaptation with age for amino acids related to proline; this means that this model should be, with regard to this type of amino acid (arginine, proline, glutamate, and so on), nice for the study of amino acid supplementation in infants, but inadequate for adults. Baracos: Well, that’s all it is. It is a model and it is a model of infants, having no particular relevance to adults. You would have to ask the question in ‘‘something’’ that looked like an adult. This is the species-specific stuff, and the developmental stage stuff that you are stuck with. I just find it a compelling data set, because it says a whole lot about the biology of the gut, but how that plays out in different species and developmental stages, we do not yet know.