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Ascorbate‐induced hyperoxalaemia has no significant effect on lactate generation or erythrocyte 2,3, diphosphoglycerate in dialysis patients
Author(s) -
TOMSON C. R. V.,
CHAN S. M.,
WARD M. K.,
LAKER M. F.
Publication year - 1990
Publication title -
european journal of clinical investigation
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.164
H-Index - 107
eISSN - 1365-2362
pISSN - 0014-2972
DOI - 10.1111/j.1365-2362.1990.tb01878.x
Subject(s) - medicine , ascorbic acid , anaerobic exercise , endocrinology , venous blood , oxalate , bicarbonate , diphosphoglycerate , taurine , chemistry , biochemistry , physiology , hemoglobin , food science , organic chemistry , amino acid
. To examine the possible effects of hyperoxalaemia on anaerobic metabolism and erythrocyte pyruvate kinase activity, we induced a rise in plasma oxalate in 11 dialysis patients by the oral administration of ascorbic acid, 500 mg day ‐1 for 3 weeks. Blood samples were taken from the same antecubital vein before and after the supplementation period, without venous stasis, after an overnight fast. This protocol allowed patients to be used as their own controls. Five healthy subjects underwent an identical protocol to exclude any effect of ascorbate per se . Mean (SEM) plasma oxalate (μmol l ‐1 ) rose from 30.3 (3.5) to 48.4 (6.1) in patients and from 1.4 (0.2) to 6.8 (0.9) in healthy subjects. Whole blood ascorbate (mgl ‐1 ) rose from 70 (0.7) to 26.6 (2.5) in patients and from 9.3 (1.2) to 17.8 (1.8) in healthy subjects (reference range 7.5–20.0 mg l ‐1 ). No changes were observed in either group in plasma creatinine, bicarbonate, haemoglobin, or erythrocyte 2,3, diphosphoglycerate (2,3 DPG) after the 3 week supplementation period. Before supplementation lactate generation (area under curve, mmol min l ‐1 ) in the 5 min following a 60 s period of standardized ischaemic forearm exercise was significantly ( P = 0.026) greater in patients [69.1 (4.7)] than in healthy subjects [46.9 (6.7)]; no significant change in lactate generation occurred in either group after ascorbate‐induced hyperoxalaemia. We conclude that changes in plasma oxalate of the order of 20 μmol l ‐1 have no significant effect on lactate generation or 2,3, DPG levels in uraemic subjects.,