Enhanced ultrafiltration in rabbits with bicarbonate glycylglycine peritoneal dialysis solution

The aim of the study was to investigate net ultrafiltration (NUF) with a new bicarbonate glycylglycine (BiGG) peritoneal dialysis solution compared to the standard lactate (La) solution.

In six groups of 12 normal rabbits each we measured NUF after a 2-, 4-, and 6-hour peritoneal dialysis with a BiGG solution (pH 7.35) and a standard La solution (pH 5.5) of similar glucose, electrolyte, and osmolality formulation. Furthermore, we studied the phosphatidylcholine concentration in the effluent of the two solutions.

NUF volume was significantly greater with the BiGG rather than with the La solution by approximately 15% (p < 0.05), 30% (p < 0.01), and 40% (p < 0.005) at 2, 4, and 6 hours, respectively. The glucose absorption rate was greater with the La solution than with the BiGG solution, but the difference was significant only at 2 hours (p < 0.05). pH was increased in the La solution from its initial value of 5.5 to 7.18, 7.32, and 7.40 at 2, 4 and 6 hours, respectively, while it remained almost unchanged in the BiGG solution. Phosphatidylcholine (PC) in the peritoneal effluent was significantly higher in the BiGG solution in all instances (p < 0.0001).

It is concluded that the BiGG solution, which has a stable pH, 7.35, due to the potent buffering capacity of bicarbonate and glycylglycine, enhances peritoneal NUF by maintaining a higher osmotic gradient and retarding lymphatic absorption through an increase in PC concentration in the peritoneal cavity.