Isolation and chemical identification of inhibitors of plasma ligand binding

The concentration changes, during hemodialysis treatment, of 18 characteristic uremia compounds, analyzed by high-pressure liquid chromatography in sera of renal patients were studied. Pre- to postdialysis concentration ratios (dialysis ratio, D) varied from 0.83 to 3.04 for the different solutes. A division into three solute groups, on the basis of their D values, could be rationalized qualitatively from data on protein binding and dialyzer clearance. One group showed low dialysis ratios which could be explained from plasma protein binding. The second group had intermediate D values, comparable to those of creatinine. For some of the members of the third group, high D values might indicate a compartmentalization and resistance to mass transfer across biological membranes. Among the latter are the tubularly secreted hippuric acid and p-hydroxyhippuric acid. For most of the (protein-bound) solutes, protein binding was shown to decrease during hemodialysis. Protein binding levels were higher after dialysis only for hippuric acid and the as yet unidentified fluorescent solute designated UFK8. In conclusion, the change of serum concentrations and of protein binding resulting from hemodialysis treatment are presented and are compared for 18 accumulating solutes in sera of patients with end-stage renal failure.

Section: Discussionmentioning

confidence: 99%

Effect of Hemodialysis on Serum Concentrations of HPLC-Analyzed Accumulating Solutes in Uremia

Schoots

Peeters

Gerlag³

1989

“…Ultrafiltration is a currently used method for the de termination of drug and solute protein binding [6,[14][15][16]. It could be argued that this procedure does not allow the exact estimation of true free concentrations, but Whitlam and Brown [17] demonstrated that binding equilibria are not disturbed by ultrafiltration techniques.…”

Section: Discussionmentioning

confidence: 99%

Correlation of a Colorimetric and a HPLC Method for the Determination of Serum Hippuric Acid Concentrations in Uremia

Vanholder

Smet²,

Schoots³

et al. 1988

Hippuric acid has been recognized as a potential marker of uremic toxicity in chronic renal failure. However, in most studies, serum hippuric acid concentrations have been determined by sophisticated methods, such as high-performance liquid chromatography. The present study was undertaken to evaluate whether the less complicated colorimetric determination method could replace such methods. Based on 21 different samples, the results obtained by both methods appeared to be correlated to each other in a highly significant way (total hippuric acid: r = 0.99, p < 0.001; free hippuric acid; r = 1.00, p < 0.001). Mean total and free hippuric acid concentrations and mean percent protein binding, obtained with both determination methods, were also identical. It is concluded that both the colorimetric method and high-performance liquid chromatography are equally reliable for the study of the concentration of hippuric acid in uremic serum and of its importance as a marker of the clinical and biochemical epiphenomena of uremic toxicity.

“…The present method will be used to further assess the role of hippurate as one component in uremic plasma which may account for the impaired binding of small ligand (drugs and metabolites) to plasma albumin in uremia [9]. We will measure plasma concentrations of hippurate and of indoxyl sulfate, which is also retained in renal failure [19], over a wide range of renal function and correlate their levels with the degree of impaired ligand binding.…”

Section: Discussionmentioning

confidence: 99%

“…This method, however, failed to resolve hippurate from />-hydroxyphenylacetate, another potential uremic binding inhibitor [9], A series of gradient steps were therefore developed to solve this problem. Typical chromatograms for normal and azotemic plasma with the method chosen are shown in figure 1.…”

Section: Precision Anil Reproducibilitymentioning

confidence: 99%

“…A partially purified extract from uremic body fluids generates this binding defect when added to normal plasma and interferes with the secretion of PAH by rat kidney [6][7][8]. Hippurate has been identified as one component in this extract [9], Clear proof of a role for hippurate in the binding defect would require several lines of evidence. First, its concentration in uremic plasma should be measured and correlated with the extent of binding abnormality.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Plasma Hippurate in Renal Failure: High-Performance Liquid Chromatography Method and Clinical Application

Igarashi

Gulyassy

Stanfel

et al. 1987

We have developed a high-performance liquid chromatography (HPLC) method for assay of hippurate in plasma of patients with renal failure. Hippurate accounts, in part, for the impaired binding of drugs and metabolites to albumin and may cause other disorders in azotemic patients. The method is precise, accurate and reproducible. Among 25 patients with acute and chronic renal failure having serum creatinine in the range of 2.9–43 mg/dl (256–3,801 μmol/l), plasma hippurate ranged from 0.11 to 16.2 mg/dl (6.1–904 μmol/l). Hippurate concentration correlated moderately closely with plasma creatinine, urea and anion gap. Its curvilinear relation to the reciprocal of serum creatinine indicated a proportional decline of GFR and tubular function or the accumulation of inhibitors of the proximal tubular anion secretory pathway. The method should be useful for further studies of abnormal albumin binding as well as other disorders in azotemic patients.