Intestinal microcirculation and transmucosal fluid transport.

Blood and lymph capillaries play an important role in removing absorbed fluid from the interstitium of the intestinal mucosa. Data from the literature indicate that hydrostatic and oncotic pressures within the mucosal interstitium primarily determine the partition of absorbed fluid between blood and lymph. Alterations in the density of perfused capillaries and/or capillary permeability during absorption also influence the effectiveness of blood capillaries in removing absorbed fluid. An hypothesis regarding the roles of the interstitium, lymphatics, and capillaries during fluid transport is presented that is based mostly on whole organ studies. The effects of interstitial fluid compartmentation on interpretations of whole organ data are also discussed.