Peritoneal Dialysis International, Vol. 13, pp 280-288 0896-8608/93 $300 + 00 Printed in Canada All rights reserved Copyright &copy; 1993 International Society for Peritoneal Dialysis PERITONEAL TRANSPORT DURING DIAL YSIS WITH AMINO ACID-BASED SOLUTIONS Min Sun Park,1,2 Olof Heimb&uuml;rger,1 Jonas Bergstr&ouml;m,1 Jacek Waniewski,3 Andrzej Werynski,3 and Bengt Lindholm1 Department of Renal Medicine, 1 Karolinska Institute, Huddinge University Hospital, Stockholm, Sweden; Hyonam Kidney Laboratory,2 Soon Chun Hyang University, Seoul, Korea,. Institute of Biocybernetics and Biomedical Engineering,3 Warsaw, Poland .Objective: To evaluate the potential clinical role of amino acids as an osmotic agent. .Design: The peritoneal transport of fluid, amino acids, and other solutes was investigated during a 6-hour single-cycle peritoneal dialysis with PDA 1% versus 1.36% glucose (n=6) or PDA 2.7% versus 3.86% glucose solution (n=9). .Patients: Fifteen stable nondiabetic continuous ambulatory peritoneal dialysis (CAPD) patients. .Results: The fractional absorption of the osmotic agents at 6 hours was higher with PDA 2.7% versus glucose 3.86% (p<O.OO5). The diffusive mass transport coefficient, KeD' calculated for a period of dialysate isovolemia was higher with PDA 2.7% versus PDA 1% for essential, nonessential (p<0.005), and total (p<0.05) amino acids. The intraperitoneal volume-over-time curves and KqD values for urea, creatinine, glucose, albumin, &beta;2microglobulin, and total protein did not differ between the amino acid solutions and the corresponding glucose solutions. KeD for urea was significantly higher during the dwell with PDA 2.7% versus PDA 1% (p<0.05). Plasma amino acid concentrations increased substantially during the first 1-2 hours and then decreased gradually. Valine and methionine rose to 792% and 1119% of baseline values, respectively. .Conclusions: We conclude that the peritoneal trans port of fluid and investigated solutes, except amino acids, was not different with the amino acid solutions compared with the corresponding equimolar glucose solutions. However, ultrafiltration tended to be lower with amino acid solutions. Furthermore, the fractional absorption of amino acids and KeD values for amino acids was higher with PDA 2.7% versus PDA 1 %, suggesting an effect of the hypertonic amino acid solution on the peritoneal membrane transport properties. Also, the hypertonic PDA2.7% solution yielded nonphysiologically high plasma levels of several amino acids. We therefore consider this solution not to be safe enough for long term clinical use. " KEY WORDS: Amino acids; solute transport. Correspondence to: Bengt Lindholm, Department of Renal Medicine K 56, Huddinge University Hospital, S- 14186 Huddinge, Sweden. Received 23 November 1992; accepted 4 May 1993. U remia is associated with a variety of metabolic and nutritional derangements, including glu cose intolerance, hyperlipemia, protein-energy malnutrition, and amino acid abnormalities ( 1 ). During peritoneal dialysis, the removal of essential nutri ents such as proteins, amino acids, and water-soluble vitamins may aggravate metabolic and nutritional disturbances (2,3). In addition, various metabolic and nutritional problems including hyperlipemia, hyperglycemia, and obesity may arise due to the continuous absorption of glucose from the dialysate (3,4). To overcome problems associated with glucose absorption, to compensate for protein and amino acid losses as well as inadequate dietary protein intake, and ultimately, to improve the nutritional status of continuous ambulatory peritoneal dialysis (CAPD) patients, amino acids were proposed as an osmotic agent in peritoneal dialysis fluids (5,6). There are now several reports that amino acids could be as effective as glucose as osmotic agents (713) and that amino acid- based solutions may promote a positive nitrogen balance and result in increased concentrations of visceral proteins, improved amino acid profiles, and improved anthropometric meas ures ( 10, 11, 14, 15). It is also possible that amino acid solutions may improve lipid abnormalities in patients on peritoneal dialysis (12,13). The effect of amino acid solutions on the peritoneal transport properties is, however, still not established. Stable as well as increased peritoneal permeability (16) has been reported during long-term use of a 1% amino acid solution, and increased permeability during a single exchange of 2.7% (9,17) or 2.59% (18) amino acid solution has also been reported. To further evaluate peritoneal transport during dialysis with amino acids as an osmotic agent, we investigated the transport of amino acids from the peritoneal cavity to the blood and the transport of fluid and solutes through the peritoneal barrier during a 6-hour single cycle of peritoneal dialysis with solutions containing either 1% or 2.7% amino acids. Investigations with 2.7% amino acid solutions were initiated before a possible adverse effect of hypertonic amino acid solutions was reported.