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Division of Nephrology,1 Department of Medicine; Department of Experimental Hepatology 2 and Department of Cardiovascular Pathology,3 Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
Correspondence to: R.T. Krediet, Division of Nephrology, F4-215, Academic Medical Center, Meibergdreef 9, 1105 AZ, Amsterdam, The Netherlands. c.n.deboer{at}amc.uva.nl
Background: Conventional lactate-buffered peritoneal
dialysis (PD) fluids containing glucose and glucose degradation products are
believed to contribute to the development of fibrosis and angiogenesis in the
dialyzed peritoneum. To reduce potential negative effects of lactate, pyruvate
was substituted as a buffer and its effects on peritoneal pathological
alterations were studied in a chronic peritoneal exposure model in the
rat.
Methods: 20 Wistar rats were infused intraperitoneally
with pyruvate-buffered (n = 9) or lactate-buffered PD fluid. After 20
weeks of daily infusion, peritoneal function was assessed. In omental
peritoneal tissue, the number of blood vessels was analyzed following
alpha-smooth muscle actin staining. The degree of fibrosis was quantitated in
Picro Sirius Red-stained sections and by assessment of the hydroxyproline
content. Plasma lactate/pyruvate and betahydroxybutyrate/acetoacetate (BBA/AA)
ratios were determined. Plasma and dialysate vascular endothelial growth
factor (VEGF) levels were quantitated by ELISA.
Results: The mass transfer area coefficient of
creatinine was higher and the dialysate-to-plasma ratio of sodium was lower in
pyruvate-treated animals compared to the lactate-treated group (0.11 vs 0.05
mL/min, p < 0.05, and 78% vs 89%, p < 0.05). The
BBA/AA ratio tended to be lower in the pyruvate animals (p = 0.07).
The number of blood vessels was lower in pyruvate-treated animals (16 vs 37
per field, p < 0.001). Total surface area, luminal area, and
wall/total area of the vessels were larger in the pyruvate group. The degree
of fibrosis was lower in intersegmental and perivascular areas of
pyruvate-exposed animals. Effluent VEGF was higher in the pyruvate
group.
Conclusions: Replacement of lactate by pyruvate
resulted in changes in peritoneal solute transport, accompanied by a reduction
in both peritoneal membrane angiogenesis and fibrosis, suggesting potentially
novel mechanisms to reduce glucose-driven alterations to the peritoneal
membrane in PD patients.
KEY WORDS: Pyruvate; angiogenesis; pseudohypoxia; polyol pathway; peritoneal fibrosis.
Received 17 August 2007; accepted 24 March 2008.
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