Efeito de variações agudas do volume do líquido extracelular sobre a resistência do segmento ileocolonico ao fluxo de salina em cães anestesiados

Abstract

Acute ECF volume expansion increases the resistance of the gastroduodenal segment - perfused at constant pressure- to saline flow while retraction decreases it. ECF volume changes also modify sodium and water transport in the small bowel. Acute ECF volume expansion decreases absorption and increases secretion. Retraction, conversely, maximizes absorption and reduces or even halts secretion. However, there is no observation relating ileocolonic motility and acute ECF volume changes. Considering that reduced and increased intestinal tone are, respectively, related to increased and reduced absorption as well as to decreased and increased secretion one can say that acute ECF volume changes modulate both GI tract motor activity and salt and water transport to meet acute organic needs for liquid volume. Increased and reduced gastroduodenal resistance to saline flow respectively in response to ECF volume expansion and retraction, helped us predict and recently demonstrate that expansion delay physiological gastric emptying of liquid (full paper submitted to publication). To further sketch the ECF volume change effects on GI tract motor behaviour we extended the perfusion experiments to the ileocolonic region and approached the neural mechanism involved.