点击显示 收起
Department of Nephrology and Research Unit, Hospital Nuestra Señora de Candelaria, 38010 Santa Cruz de Tenerife, Tenerife, Spain, E-mail: jnavarro{at}hcan.rcanaria.es
Dear Sir:
We thank Solomons et al for their interest in our study on amino acid losses during hemodialyisis with polyacrylonitrile membranes and the effect of intradialytic amino acid supplementation (1). We are glad to have the opportunity to respond to the issues they raised.
First, glutamine is not contained in the amino acid solution. The composition of infused amino acid solution was shown in Table 2 of our article and, as the authors commented, glutamine was not included. The amino acid infusate used in our study was Aminoplasmal (Braun Medical, Barcelona, Spain). For the purposes of the investigation we used a solution easily available and widely used in clinical practice daily, instead of a specifically prepared amino acid solution, even though several of the nonessential amino acids (citrulline, glutamine, and taurine) were not contained in the preparation.
Second, even though citrulline, glutamine, and taurine were not contained in the amino acid solution, we decided to analyze the hourly losses and the plasma concentrations of these amino acids during the dialytic procedure (Tables 3 and 4). As is logical, and again in agreement with Solomons et al, because these amino acids were not administered during hemodialysis, their serum concentrations experienced the greater decrease during dialysis with supplementation, with no significant differences in the percentage of reduction with respect to dialysis without supplementation. Furthermore, and not surpringsly, citrulline, glutamine, and taurine are the only 3 amino acids that have no greater losses during dialysis with supplementation (Table 5).
Third, glutamine, unlike the essential amino acids that must be externally supplemented, is a nonessential amino acid that is synthesized by physiologic metabolic reactions from glutamic acid and ammonia. This amino acid was not included in Table 6 because that table depicted the net balance of individual amino acids during hemodialysis with amino acid supplementation. Glutamine, citrulline, and taurine were not included in Table 6 because the net balance of amino acids, as specified in the methods section, was calculated as (amino acid contained in the infusate) - (amino acid lost into dialysate with supplementation) - (amino acid lost into dialysate without supplementation). Therefore, the net balance of the amino acids not contained in the infusate could not be calculated.
Finally, we thank Solomons et al for their interesting comments on the solubility of glutamine dipeptides and their potential use in intradialytic amino acid supplementation.
REFERENCE