Isolated colonic loop in the rabbit: an in vivo system for studying intestinal mucus

A method for preparing an isolated colonic loop (Thiry-Vella) in a living rabbit is described. The loop, with its intact neurovascular supply, continues to secrete clear colonic mucus for more than 2 months. The chemical composition of the mucus, collected daily for 2 months, was analyzed and shown to be a high molecular weight glycoprotein composed of approximately equimolar amounts of protein and carbohydrate. The main sugars found were N-acetylgalactosamine, N-acetylglucosamine, galactose, and sialic acid. The most prominent amino acids were threonine, aspartic acid, glycine and serine. A considerable flattening and atrophy of the glandular structure of the isolated colonic loop was observed during the 2 months. This fact did not markedly affect the amount and chemical composition of the mucus that was collected daily from this loop. This model can be used in vivo to investigate colonic mucus in normal and diseased animals, or even following the administration of various drugs.