Net Sodium and Glucose Transport in the Jejunum, Ileum and Colon of Anaesthetized Rats in Response to Intraluminal Theophylline and Anionic Surfactants

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Abstract
Osmotically balanced solutions of NaCl and glucose (5-150 mmol/l) were instilled into rats prepared with 2 tied intestinal loops. Luminal accumulation or disappearance of Na+ and glucose after 15 min was determined, and the parameters of the linear regression lines of net Na+ flux (y) with initial Na+ concentration (x) calculated. Control cation and glucose transport were changed by dioctylsulfosuccinate and dodecylsulfate. Theophylline (10-25 mmol/l) did not alter glucose disappearance, and had a distinctly dissimilar effect on net Na+ transport compared to the surfactants. This could be described as a parallel displacement of the control regression lines to the right, without improvement in correlation. This effect of theophylline was greatest in the ileum, where mean luminal Na+ concentration corresponding to zero net transport was raised from .apprx. 70 mmol/l under control condition to values > 200 mmol/l. Theophylline mainly affects transcellular and the surfactants mainly paracellular Na transport. Apparently the dioctylsulfosuccinate effect on intestinal transport is not related to an activation of the mucosal adenylate cyclase/cAMP system, at least not in short-term experiments.