One-compartment model for amino acids and other biological molecules in peritoneal dialysis.
OBJECTIVE
Investigation of the main factors determining the concentration-time course of amino acids and biological molecules in serum and dialysates.


METHODS
In a randomized, 3-period crossover study, 11 patients were treated once with each of 3 peritoneal dialysis solutions, 1 containing amino acids and bicarbonate, 1 containing glucose and bicarbonate and 1 containing glucose and lactate. Nineteen amino acids, 3 proteins, 2 metabolites and 2 ions were measured in serum and dialysate. A standard compartment model was fitted to the data.


RESULTS
The amino acids differed significantly in their kinetic characteristics (p < 0.001), mainly volume of distribution and elimination rate. Differences in absorption were small compared to the interpatient variation. The average transport rate from serum to dialysate was 0.50-1.14 h(-1), from dialysate to serum 0.33-0.41 h(-1), for elimination from the central compartment 0.35 to 2.27 h(-1), for volume of distribution 0.29 to 0.83 l/kg, for serum protein binding 19-47%, for amount in tissue 82 - 95%, for endogenous metabolic rate 16-151 micromol x kg(-1) x h(-1). The volume of distribution correlated with the R group (polar positive < aliphatic < polar uncharged). For the various proteins, the 2 bicarbonate solutions had higher serum-to-dialysate transport rates than the lactate solution (p = 0.018-0.601).


CONCLUSIONS
The compartment model demonstrated its usefulness. Accordance with literature data for healthy volunteers indicated the validity of the estimates.
de la Motte
S
S
Harrison Clinical Research, Munich, Germany. sdelamotte@t-online.de
Plum
J
J
Passlick-Deetjen
J
J
Grabensee
B
B
D000328:Adult; D000368:Aged; D000596:Amino Acids / Q000378:metabolism*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D008954:Models, Biological; D010530:Peritoneal Dialysis
D000596:Amino Acids