Vagal control of fluid transport, transmural potential difference, and motility in the ferret jejunum

The role of the vagus nerve in the control of intestinal transport was investigated in the ferret jejunum in vivo. Fluid transport was measured in an isolated 10-cm segment of jejunum by means of a single-pass perfusion technique with radioactive markers introduced into the perfusion fluid and the bloodstream of the animal. Transmural potential difference (PD) and intraluminal pressure in the perfused jejunal loop were also monitored. Vagal stimulation (20 Hz, 20 V, and 0.5 ms for 1 min) resulted in jejunal fluid movement in the direction of secretion, a rise in transmural PD, and an increase in jejunal contractile activity. Similar changes were induced by close intra-arterial injection of acetylcholine (20 micrograms X kg-1). The contractile response to vagal stimulation was abolished by atropine. Moreover, atropine did not block the changes in fluid transport and transmural PD that were induced by vagal stimulation, although the transmural PD response was reduced. The results suggest that vagal stimulation induces intestinal secretion accompanied by a rise in transmural PD; the events are mediated at least in part by a noncholinergic transmitter as yet undetermined.