EFFECT OF CHRONIC RENAL DYSFUNCTION ON THE PERMEABILITY OF THE COLON TO WATER AND ELECTROLYTES: EXPERIMENTAL STUDY IN RATS

Abstract

ABSTRACT Background: Renal insufficiency is a disease that affects several organs by provoking hypervolemia and uremia. The disease reaches more than 500 million people worldwide and few studies bring their influence on the gastrointestinal tract. Aim: To evaluate the influence of 5/6 nephrectomy-induced hypervolemia on colonic permeability to water and electrolytes. Method: Sixty male Wistar rats weighing between 280-300 g were divided into three groups: 3, 7 and 14 days after nephrectomy, each one having a false-operated/control and partially nephrectomized. For colonic permeability they were submitted to colonic perfusion with a solution of Tyroad containing phenolphthalein. Differences among the concentrations of Na+, K+ and Cl- were used to calculate the rate of colonic permeability for the electrolytes. Phenolphthalein concentrations were used to evaluate the rate of secretion and water absorption. Results: The colonic secretion of water and electrolytes occurred expressively in the group seven days after nephrectomy. Hemodynamic and biochemical assessments determined the progression of renal failure in all three groups and polyethylene glycol was shown to be effective in reversing the secretory capacity of the colon. Conclusion: Hypervolemia established after 7 days post-nephrectomy 5/6 caused marked colonic secretion for water and electrolytes. The organism presents progressive colonic secretion as the blood volume increases; on the other hand, polyethylene glycol was able to revert this secretory framework of the colon to water and electrolytes by reversing the hypervolemia.