The effect of phosphate loading on erythrocyte 2,3-bisphosphoglycerate levels.
BACKGROUND
Phosphate supplementation has been used in an effort to enhance athletic performance by increasing erythrocyte 2,3-bisphosphoglycerate levels ([2,3-BPG]) and hence improve oxygen offloading from haemoglobin. Claimed effects of phosphate loading upon both exercise performance and erythrocyte [2,3-BPG] are inconsistent, and the basis of any change in [2,3-BPG] is unknown.


METHODS
We analysed plasma inorganic phosphate concentration ([P(i)]) and erythrocyte [P(i)] and [2,3-BPG] in venous blood samples from 12 healthy subjects. We re-examined a subset of five of these subjects after 7 days of phosphate loading.


RESULTS
There were significant positive correlations between plasma [P(i)] and erythrocyte [P(i)] (r(2)=0.51, p=0.009) and between erythrocyte [P(i)] and [2,3-BPG] (r(2)=0.68, p<0.001). Following phosphate loading, there was a 30% increase in plasma [P(i)] (1.02+/-0.22 to 1.29+/-0.15 mmol/l (mean+/-S.D.), p=0.03) and a 25% increase in erythrocyte [2,3-BPG] (6.77+/-1.12 to 9.11+/-1.87 mmol/l cells, p=0.03). There is no relation between [2,3-BPG] and plasma [P(i)].


CONCLUSIONS
Phosphate loading increases both plasma and erythrocyte phosphate pools and the rise in [2,3-BPG] is probably a consequence of the rise in cell [P(i)].
Department of Biochemistry, University of Sydney, Sydney, Australia.
Kyla
K
Bremner
William A
WA
Bubb
Graham J
GJ
Kemp
Michael I
MI
Trenell
Campbell H
CH
Thompson
D019794:2,3-Diphosphoglycerate / Q000032:analysis* / Q000097:blood; D000328:Adult; D004912:Erythrocytes / Q000737:chemistry* / Q000187:drug effects*; D005260:Female; D006801:Humans; D016015:Logistic Models; D008297:Male; D010710:Phosphates / Q000008:administration & dosage* / Q000097:blood* / Q000494:pharmacology*
D010710:Phosphates; D019794:2,3-Diphosphoglycerate; C018279:sodium phosphate