Electrolyte, urea, and water movements across canine intestinal mucosa

¹ Department of Physiology, Northwestern University Medical School, Chicago, Illinois

Solutions of varying chemical and osmotic composition were perfused through isolated upper or lower bowel loops in unanesthetized dogs. Enterosorption and absorption of solute ions were measured separately and an apparent insorption rate of solutes was estimated. The latter increased nearly linearly with log perfusate concentration. The slope constants ( insorption/ log conc.) differed among ions and differed for a given substance when certain other ions were present. Insorption rates at a standard solute concentration (100 mm/liter) ranged from 15 mm/hr for urea to .62 mm/hr for calcium (chloride). Sodium and potassium (chloride) rates averaged 4.35 and 3.1 mm/hr, respectively. Water enterosorption increased linearly with log perfusate osmolarity for all perfusates. However, at a standard perfusate concentration (278 mOs/liter), water absorption ranged from 4.3 m/hr for urea to .4 m/hr for CaCl₂. Concomitant solute insorption and water absorption rates were correlated significantly.