Establishment of a Blood Purification System for Renal Failure Rats Using Small‐Size Dialyzer Membranes

Hemodialysis techniques for small animals have not been established because no small dialysis apparatus has been available. We recently developed a small‐size dialyzer and established an appropriate blood purification system for small animals. To confirm the appropriate dialysate flow rate, bovine blood was dialyzed for 60 min at a fixed blood flow rate of 1.0 mL/min and variable dialysate flow rates. Blood urea nitrogen and creatinine levels decreased significantly at a dialysate flow rate of 5 mL/min (from 13.7 ± 0.2 to 10.3 ± 1.2 mg/dL and 1.07 ± 0.15 to 0.61 ± 0.12 mg/dL, respectively, P  < 0.05). To determine the appropriate in vivo conditions, extracorporeal circulation was performed in anesthetized male Sprague‐Dawley rats at a dialysate flow rate of 0.0 mL/min, for 240 min, and at variable blood flow rates. Extracorporeal circulation was successful at a blood flow rate of 1.0 mL/min, but not 1.5 mL/min. To establish in vivo hemodialysis conditions, we used the animal model of end stage renal failure. Sprague‐Dawley rats were fed a 0.75% adenine‐containing diet for 3 weeks, after which they received hemodialysis for 120 min at a dialysate and blood flow rate of 5.0 and 1.0 mL/min, respectively. There were no significant changes in systolic blood pressure or heart rate during dialysis. Thus, this blood purification system can be safely used for small animals at a dialysate flow rate of 5.0 mL/min and a blood flow rate of 1.0 mL/min. This system provides a basis for further research on hemodialysis therapy.