Dialysis of plasma soluble lipofuscins in patients with end-stage renal failure

Fluorescence spectrophotometry demonstrates that the levels of plasma soluble lipofuscins (SL) in patients with end-stage renal failure, undergoing continuous ambulatory peritoneal dialysis (CAPD) or haemodialysis (HD), remain significantly higher than in normal subjects. Plasma samples from these patients show the presence of SL generated from 3-hydroxy-anthranilic acid [excitation (ex) at approximately 324 nm and emission (em) at approximately 413 nm] and of other SL generated from dopa, catecholamines, 3-hydroxykynurenine and from structurally related precursors (ex at approximately 345 nm, em at approximately 445 nm). These precursors form the melanin components, which are approximately 3 wt % of SL. The fluorescence of SL appears to originate mainly from the melanin components. Peaks and shoulders at these wavelengths are found in the spectra of all dialysates. Based on intensity measurements at 413 nm and 445 nm, the weekly clearance rates with HD are in general greater than those with CAPD. The saponified cellulose ester membrane used in HD passes only lower-molecular-weight SL and/or components of SL. After HD, the greatest reductions in plasma intensities are found at approximately 324 nm and approximately 413 nm. The clearance rates (l/week) are always greater at 413 nm [means HD: 18.47 +/- 4.44 standard deviation (SD), n = 8; CAPD: 12.50 +/- 2.47, n = 4] than at 445 nm (HD: 10.94 +/- 3.86; CAPD: 7.95 +/- 1.75) both with HD and CAPD. In CAPD, the membrane also permits the passage of large amounts of albumin and other high-molecular-weight substances.(ABSTRACT TRUNCATED AT 250 WORDS)