EFFECT OF CHOLERA-TOXIN ON GLUCOSE-ABSORPTION AND NET MOVEMENTS OF WATER AND ELECTROLYTES IN THE INTESTINAL LOOP OF SHEEP

This study was designed to evaluate the effect of cholera toxin on glu cose absorption and net movement of water and electrolytes in the jeju nal loop of sheep. Intraluminal perfusion was performed at the rate of 1 ml/min with isotonic 10 mM glucose solution. Osmolality was adjuste d by adding NaCl, and the outflow solution was collected every 10 min. After a 30 min control period, cholera toxin was applied intraluminal ly for 30 min at doses of 30, 60, and 120 mu g/loop. In the control pe riod, water, sodium and chloride were absorbed, while potassium and bi carbonate were secreted. Cholera toxin reversed the net absorption of water, sodium and chloride to net secretions, and this secretory respo nse to cholera toxin was dose-dependent. Bicarbonate secretion was sti mulated dose-dependently by cholera toxin. Potassium secretion was als o increased at all doses, though this response was not dose-dependent. The net glucose absorption was decreased dose-dependently by cholera toxin. In conclusion, these results indicate that cholera toxin stimul ates water and electrolyte secretion, and inhibits glucose absorption in the jejunal loop of sheep.