Review Glutamine Metabolism by the Intestinal Tract

The gastrointestinal tract is generally viewed as an organ of digestion and absorption, designed to extract nutrients from the intestinal lumen and deliver them into the bloodstream. Fats, for example, are packaged into chylomicrons by the enterocytes of the small bowel and transported via lymphatics to the systemic circula-tion. On the other hand, simple sugars and amino acids, the major products of carbohydrate and protein hydrol-ysis, are absorbed by specific carriers on the luminal side of the intestinal epithelium and subsequently trans-ported across the basolateral membrane into the portal blood. Because of their anatomic relationship, the gut and liver play a central cooperative role in the handling and processing of ingested nutrients. Recent studies have demonstrated that the gastroin-testinal tract actively metabolizes circulating sub