Action of aldosterone upon the intestinal transport of potassium, sodium, and water.

Cardiff EDITORIAL COMMENT This study continues the work described in the previous paper and brings out another common factor concerning electrolyte transport. The action of the adrenal mineralocorticoids upon the intestinal mucosa closely resembles their effect upon the renal tubular epithelium (Shields, 1964). Thus, in both organs, the transfer of potassium into the lumen is stimulated by the intravenous administration of aldosterone Because the renal action of the mineralocorticoids can be blocked by the spironolactones (Bartter, 1960) the effect of these agents upon the intestinal action of aldosterone was investigated. METHOD The movement of potassium, sodium, and water into and out of the lumen of isolated segments of ileum (two dogs) and of colon (three dogs) was measured using the radioactive isotopes of sodium and potassium, and the stable isotope of water, deuterium oxide. Details of the preparation and of the experimental technique are given in the previous paper (Shields et al., 1966). TYPES OF EXPERIMENT In each dog, six types of experiment were performed: I Spironolactone alone One hundred mg. spirono-lactone SC 9420 (Aldactone, Searle) was given by mouth at 6.00 a.m. At 9.00 a.m. an intravenous infusion of 5 % (w/v) dextrose was set up and continued at a rate of 40 ml. per minute. Absorption tests, each lasting 10 minutes, were performed at 1, 2, 2j, 3i, 4, and 5 hours after the beginning of the dextrose infusion. One such experiment was performed in each dog. 2 Spironolactone + aldosterone (high dose) The experimental technique was identical to (1), except that at 9.00 a.m., 250 pg. aldosterone (Aldocorten, Ciba) was injected intravenously and a further 250 ,tg. was added to the dextrose solution and delivered to the dog at a rate of 1 jig. per minute. One experiment of this type was performed on each dog. 3 Spironolactone + aldosterone (low dose) The experiment was similar to (1), except that aldosterone was added to the dextrose solution and infused intravenously at a rate of 8 ug. per hour. Two experiments of this type were performed on each dog. 4 Aldosterone (high dose) alone The technique was identical to (2) except that spironolactone was not given. Two such experiments were performed on each dog. 5 Aldosterone (low dose) alone The experimental procedure was identical to (3) except that no spirono-lactone was administered. One experiment of this type was performed upon each dog. 6 Control experiments Neither aldosterone nor …