Separation of adaptive mucosal growth and transport after small bowel resection.

In rats 70% of the small bowel was resected with preservation of duodenum and terminal ileum. Two and four weeks later transport of sodium, chloride, water, and galactose was studied in duodenum and ileum. Controls were sham-operated and unoperated rats. There was significant mucosal growth 2 and 4 wk after resection. By 2 wk postresection transport specific activities (transport per gram mucosa) were generally decreased. Mucosal growth compensated only sufficiently so that transport capacities (transport per centimeter segment length) remained unaltered from controls. By 4 wk postresection transport specific activities had either increased or were unchanged from controls. Therefore, in association with mucosal growth, transport capacities increased. The major adaptive increases for electrolytes and water occurred in duodenum; ileum was the site of increased galactose transport. The data indicate that 1) mucosal growth and functional transport changes occur as separate adaptive phenomena and 2) adaptive transport mechanisms are selectively localized to particular regions of the intestine.