Fluid flow across the jejunal epithelia in vivo elicited by d-c current: effects of mesenteric nerve stimulation.

The aim of this study was twofold: (1) to investigate the effect of electrical gradients on fluid transport across the rat jejunal mucosa in vivo; and (2) to evaluate the effect of mesenteric nerve stimulation (MNS) on current-induced fluid flow. Segments of rat jejunum were mounted with intact blood circulation in an in vivo chamber, allowing parallel registration of net fluid transport rate (NFT) and electrical properties of the tissue. Directed currents (d-c) of varying densities were passed across the jejunal wall in both directions and the current-induced fluid flows were measured. D-c current elicited fluid flows across the jejunal mucosa towards the cathode in both directions in a 'dose-dependent' manner. The effect was markedly greater when the anode was placed on the serosal side (s-->m current) than when it was placed on the mucosal side (m-s current). MNS abolished m-->s current induced flow whereas the effect of s-->m current was not significantly changed. It was concluded that: (1) true electro-osmosis probably accounts for the major portion of current-induced fluid flow in this model; (2) current induced fluid flow is rectified in opposite directions in vivo and in vitro; and (3) MNS inhibits current-induced fluid flow m-->s, possibly via a sympathetic effect on epithelial permeability.