Gastric emptying and intestinal transit of liquid and solid markers in rats with chronic uremia

Gastrointestinal motor abnormalities may account for dyspeptic symptoms of chronic uremia patients. However, the data on gastric emptying are conflicting in human studies. We, therefore, assessed gastric emptying and gastrointestinal transit in a rat uremia model. Chronic uremia was induced by five-sixths nephrectomy in the rats. After 20-hour fasting, the rats were loaded with 70 glass beads as solid markers through a gastric catheter. Two hours later, the stomach was exposed and the small intestine was equally divided into 10 segments. The glass beads in the stomach and in each intestinal segment were counted. The gastric emptying was expressed as the ratio of the number of glass beads in the small intestine to that counted from the entire gastrointestinal tract. The intestinal transit was assessed by analyzing the geometric center of the distribution of glass beads in the intestinal segments. Two conventional nonabsorbable markers, radioactive chromate and charcoal, were also used to evaluate gastric emptying and intestinal transit in the fasted state. Additionally, similar experiments of glass beads were performed in the fed state. It was found that, in the fasted state, the gastric emptying and the intestinal transit of liquid or solid markers were little affected by uremia. In the fed state, however, chronic uremia significantly decreased the intestinal transit but hardly affected the gastric emptying. We conclude that the postprandial intestinal transit, but not the gastric emptying, of solid markers may be decreased in the fed state by chronic uremia in a severity-dependent manner of a rat model, which resembles the findings in uremic patients.