1. Catecholamine-induced water transport was measured using an everted gut sac technique. Adrenaline, noradrenaline and isoprenaline induce dose-dependent increases in water transport by the proximal intestinal sacs. Use of selective adrenergic agents revealed the possible involvement of alpha 1- and beta 2-receptors in mediation of catecholamine stimulation of water transport in this segment. 2. Inhibition of glycolysis reduced the effect mediated through alpha 1-receptors, while the inhibition of oxidative phosphorylation blocked the beta 2-receptor mediated increase in water transport. 3. Basal transport of water was also significantly reduced by inhibition of glycolysis but was significantly elevated by blockage of oxidative phosphorylation. 4. Suppression or stimulation of glycolysis was paralleled by similar changes in lactic acid release from the gut wall. 5. It is concluded that the energy for the catecholamine-induced water transport is contributed by glycolysis and oxidative phosphorylation coupled to alpha 1- and beta 2-receptors, respectively. Under basal conditions water transport is mainly dependent on glycolysis in the segment of intestine examined.

1. This study investigated the uptake and release of phosphate from everted intestinal sacs of mice. 2. When the activity of sodium-potassium ATPase was altered (by changing the cationic concentrations in the medium by the addition of ouabain and the manipulation of metabolism by the use of selective inhibitors or stimulants), the release of phosphate appeared to be much more affected by the changes than the uptake of phosphate. 3. A small sodium gradient allowed uptake to be maintained. The addition of ouabain in the presence of an attenuated gradient significantly reduced the uptake and release of phosphate. The inhibitory effect of ouabain on phosphate release was partly reversed by an increase in the potassium concentration in serosal fluid. 4. These results indicate a role for sodium-potassium ATPase in phosphate release from the intestine.

SUMMARYEverted sacs prepared from proximal and distal parts of mouse intestine were used to study water and glucose transport in phosphate media. In the presence of high phosphate, glucose was found to increase water transport in the proximal segment but to decrease it in the distal segment. The possible mechanism of this action is discussed.

1. This study investigated the effects of fructose and 2-deoxyglucose on the uptake and release of phosphate from everted intestinal sacs of mice. 2. Both the sugars significantly decreased the release of phosphate without affecting the uptake. 3. Succinate and fumarate were able to partially reverse the inhibition of phosphate release exerted by fructose but not that exerted by 2-deoxyglucose. 4. Pre-loading with mannoheptulose, a known inhibitor of hexokinase, improved the release of phosphate in the presence of either of these sugars. 5. Adrenaline, known to inhibit phosphorylation of 2-deoxyglucose, reduced the inhibition exerted by this sugar on phosphate release. 6. These results indicate that the inhibition of phosphate release caused by these sugars may be due to the trapping of free phosphate during their metabolism in the gut wall.

Phenol Red has been widely used to test kidney function in man. Using the simple, everted gut sac technique has been observed to inhibit the phosphate transport by phenol red in the mouse intestine. We wanted to see if other similar organic anions are able to inhibit the phosphate transport across the mouse intestine. Both uptake and release of phosphate by the everted duodenal sacs of mice are inhibited by phenol red, bromocresol green and bromophenol blue. At the highest dose all the dyes were able to inhibit both influx and efflux significantly. Loss of phosphate from bathing solution is taken as influx and the gain of phosphate by the solution within the sac is taken efflux. At higher dosages a trend of increase in E/I% was noted. At the highest dose all the dyes were able to increase this parameter significantly over the control. Influx appears to be the primary process to be affected. Possible use of phenol red, on account of its safety in humans, as a hypophosphatemic agent is suggested.