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Study of the chromium binding in plasma of patients on continuous ambulatory peritoneal dialysis
F Borguet1, R Cornelis, J Delanghe
1Laboratory of Analytical Chemistry, University of Gent, Belgium.
Insights
Chromium distribution in plasma proteins of dialysis patients shows it primarily binds to transferrin. A shift to a low molecular weight complex occurs over time, with unidentified chromium species found in dialysis fluid.
Area of Science:
- Biochemistry
- Nephrology
- Radiochemistry
Background:
- Continuous ambulatory peritoneal dialysis (CAPD) involves fluid exchange, potentially altering trace element distribution.
- Understanding chromium (Cr) protein binding is crucial for patients undergoing dialysis.
Purpose of the Study:
- To investigate the distribution of chromium (Cr) among plasma proteins in CAPD patients.
- To track the kinetics of newly introduced Cr using radiolabeling.
Main Methods:
- Utilized in vitro and in vivo 51Cr-labeled plasma from three CAPD patients.
- Separated plasma proteins using ion exchange fast protein liquid chromatography (FPLC).
- Characterized proteins via isoelectric focusing and quantified albumin and transferrin using nephelometry.
Main Results:
- 51Cr distribution among plasma proteins was consistent across the three patients.
- 51Cr primarily bound to transferrin, with initial binding also observed on albumin.
- A time-dependent shift of 51Cr from albumin to an unidentified low molar mass complex (approx. 5000 Da) was noted.
- Two unidentified 51Cr species were detected in the drained dialysate.
Conclusions:
- Chromium exhibits specific protein binding patterns in CAPD patients, predominantly to transferrin.
- The formation of a low molecular weight Cr complex and its presence in dialysate warrant further investigation.
- Further research is needed to identify the low molecular weight Cr complex and dialysate species.
Abstract:
The distribution of chromium (Cr) among the proteins in plasma of three continuous ambulatory peritoneal dialysis (CAPD) patients and in dialysis solutions was studied with 'in vitro' and 'in vivo' 51Cr-labelled plasma. Radiolabelling allows the kinetics of newly added Cr to be investigated. The separation of the proteins was achieved by ion exchange fast protein liquid chromatography, ensuring quantitative recoveries of the 51Cr activity, transferrin and albumin. In all fractions the proteins were qualitatively characterised by iso electric focusing. The concentrations of transferrin and albumin were determined by nephelometry. The 51Cr distribution among the plasma proteins was similar for the three patients. The 51Cr activity was mainly bound to transferrin and, in the beginning of the incubation, in a lesser degree also to albumin. After 1-6 h a shift was observed of the 51Cr from albumin to an unidentified low molar mass complex (+/- 5000 Da). Two 51Cr species showed up in the subsequently drained dialysate, but they could not be identified.