Role of intestinal lymphatics in interstitial volume regulation and transmucosal water transport.

Two of the principal functions of intestinal lymphatics are to assist in the maintenance of interstitial volume within relatively normal limits during alterations in capillary filtration (e.g., acute portal hypertension) and the removal of absorbed water and chylomicrons. The contribution of lymphatics to the prevention of interstitial overhydration or dehydration during alterations in transcapillary filtration is similar in the small intestine and colon. While the lymphatics of the small intestine contribute substantially to the removal of absorbed water (particularly at low and moderate absorption rates), the contribution of colonic lymphatics to the removal of the fluid absorbate is negligible. This difference is attributed to the relative caliber and location of lymphatics in the mucosal layer of the small and large intestines. In the small intestine, large lacteals lie in close proximity to transporting epithelium, while colonic lymph vessels are rather sparse and confined to the basal portion of the mucosa. In the small intestine, the lymphatics assume a more important role in removing absorbed water during lipid absorption than during glucose absorption.