Intestinal recycling and substitution of haemofiltrate in dogs

Haemofiltrate was administered into the duodenum of 5 ambulatory dogs through an implanted silastic catheter at a rate of 5-10 ml/min. None of the dogs presented signs of discomfort or suffered from regurgitation or diarrhoea. All 5 dogs had solid stools, enhanced diuresis and no change in body weight over a time period of 8 hours. Filtration rates between 5 and 10 ml/min were obtained in 7 dogs after connecting an Amicon in-line Ultrafilter with an external a.v. shunt. The intestinal recycling rate via the duodenal tube as a rule was 2 ml/min lower than the free flow ultrafiltration. Recirculation of autologous haemofiltrate in 5 uraemic dogs indicated unselective reabsorption of all electrolytes and small molecules. In 5 experiments with intestinal substitution of ultrafiltrate by a potassium-free Ringer's lactate solution, correction of acidosis and decrease in plasma potassium, creatinine and BUN was achieved.