Isotonic Test Research Articles

Small bowel absorption in hypophysectomized rats.

Five, 10, 15, and 21 days after operation, absorption of sodium, chloride, water, and glucose from an isotonic test solution from the entire small bowel (from the ligament of Treitz to the ileocecal valve) of hypophysectomized rats was measured in vivo by a perfusion technic. The absorption of all these substances was decreased by approximately 50% as compared to values found in control and sham-operated rats. The sham-operated rats absorbed all substances normally. The small bowel in the hypophysectomized rats was smaller than in the controls, yet the decrease in absorption from the small bowel of hypophysectomized rats cannot be explained by a decrease in surface area alone. An undefined factor, perhaps a hormonal deficiency, seems to be responsible for the observed decreased absorption.

Effects of sodium concentration and osmolality on water and electrolyte absorption form the intact human colon.

The influence of sodium concentration and osmolality on net water and monovalent electrolyte absorption from or secretion into the intact human colon was studied in healthy volunteers. WHEN ISOTONIC SOLUTIONS CONTAINING NACL AND/OR MANNITOL WERE INFUSED INTO THE COLON: (a) a direct linear relationship between luminal sodium concentration (in the range of 23-150 mEq/liter) and rate of net water, sodium, and chloride absorption was found. No water absorption was found when sodium concentration in the luminal fluid was below 20 mEq/liter; (b) water and sodium absorption from the isotonic test solutions was not enhanced by addition of 80-250 mg/100 ml of glucose; and (c) the rate of water and sodium absorption was decreased markedly when chloride was replaced by bicarbonate in the test solution. WHEN THE COLON WAS PERFUSED WITH HYPERTONIC TEST SOLUTIONS CONTAINING NACL AND MANNITOL OR UREA: (a) water was absorbed from hypertonic NaCl solutions against a lumen-to-blood osmotic gradient of 50 mOsm/kg; (b) when the osmolality of the mannitol solution was increased, water entered the colonic lumen at a more rapid rate. The relationship between the rate of water entering the colon and the osmolality of the test solution was a parabolic one; (c) sodium and chloride entered the colonic lumen at a rate that was lineraly related to that of water entrance when the lumen-to-blood osmotic gradient exceeded 150 mOsm/kg; (d) water flow into the colonic lumen was identical when equimolar urea or mannitol solutions were infused; (e) neither urea nor mannitol was absorbed in significant amounts from the hypertonic solutions; and (f) our results suggest that the equivalent pore radius of the human colon is smaller than the molecular radius of urea (2.3 A).

Water Exchange Through the Stomach Wall: A Study in Normals and Patients with Duodenal Ulcer, Pancreatic Achylia and Gastric Achylia by Means of Deuterium Oxide

By means of an isotonic acid test meal containing deuterium oxide and reference substances, the diffusion of water through the stomach wall has been measured. In 13 normals, 7 duodenal ulcer patients and 10 patients with pancreatic achylia the mean diffusion out of the stomach was 229 d/h. In four cases of gastric achylia the corresponding figure was 189 ml/h (difference not significant). A relationship between the gastric secretory activity and the diffusion of water is suggested.