Abstract
Intestine activity is characterized by an efficient absorption of nutrients from lumen to blood; it is also characterized by large transmural fluxes of water and electrolytes and low electrical resistance. The effect of diffusional forces on net Na transport was therefore investigated. Rabbit lleum was mounted as a flat sheet between two chambers. Temperature, pressure and electrolyte solution (Ringer +10 mM glucose) were identical on both sides of the epithelium. Transmural Na fluxes were studied as a function of applied electrical potential, Ψms, (from +9 to -9mV). The net Na flux, JNanet, was found to be a linear function of Ψms (JNanet = -0.20 Ψms +1.89; r =0.99). In absence of electrochemical potential difference JNanet had the value of 2.07 ± 0.79 μeq/hr cm2), Each transmural unidirectional Na flux comprised a PD-dependent, Jd, and a PD-independent flux, J. In absence of electrochemical potential tne ratio of J from mucosa to serosa/Jd, from serosa to mucosa was 1.04, and the difference between Jc from mucosa to serosa minus Jc from serosa to mucosa was 2.07 μeq/hr cm2. These results clearly indicate the presence of two parallel pathways for Na across rabbit ileum. It is proposed that the PD-dependent pathway represents a paracellular pathway and the PD-independent pathway represents a cellular pathway.
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Desjeux, J., Tai, Y., Curran, P. et al. EVIDENCE FOR TWO PARALLEL SODIUM PATHWAYS ACROSS ILEUM. Pediatr Res 8, 898 (1974). https://doi.org/10.1203/00006450-197411000-00029
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DOI: https://doi.org/10.1203/00006450-197411000-00029