Blood flow distribution, lymph flow, villus tissue osmolality and fluid and electrolyte transport after exposing the cat small intestine to sodium deoxycholate

The effect of luminal perfusion of a dihydroxy bile salt (sodium deoxycholate) on net fluid transport, intestinal haemodynamics, lymph flow, electrolyte transport and villus tissue osmolality was studied in cat jejunum. Furthermore, the effects of hexamethonium and tetrodotoxin, two drugs influencing nervous activity, were investigated. Concomitant to net fluid secretion, the bile salt increased mucosal blood flow whereas capillary filtration coefficient and lymph flow remained unchanged. Net sodium and chloride transport changed from absorption to secretion. The change of sodium transport was due to both an increased flux from tissue to lumen and a reduced flux in the opposite direction. Villus tissue hyperosmolality was reduced. None of the effects on intestinal haemodynamics correlated with the change in net fluid transport. Furthermore, hexamethonium and tetrodotoxin inhibited the secretion of fluid and electrolytes without influencing the induced changes in intestinal haemodynamics. It is concluded that the bile salt induces intestinal fluid secretion by stimulating an active secretory process in the crypts via enteric nerves. A minor part of the total change in net fluid transport may be due to a reduced uptake in the villi.