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Electrolyte‐free milk protein solution influences sodium and fluid retention in rats
Author(s) -
Ishihara Kengo,
Kato Yoshiho
Publication year - 2013
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.27.1_supplement.632.4
Subject(s) - chemistry , sodium , endocrinology , potassium , plasma osmolality , urine , medicine , excretion , body fluid , urine osmolality , electrolyte , free water clearance , body water , zoology , body weight , biochemistry , organic chemistry , electrode , biology
Milk is an effective post‐exercise rehydration drink that maintains the net positive fluid balance. However, it is unclear which components are responsible for this effect. We assessed the effect of milk protein solution (MPS) obtained by dialysis on body fluid retention. Milk, MPS, MES (milk electrolyte solution), sports drink, and water were administered to male Wistar rats at a dose of 6 mL/rat after treadmill exercise. Total body fluid retention was assessed by urine volume 4 h after administration of hydrating liquids. Plasma osmolality, sodium and potassium levels, and urinary sodium and potassium were measured by HPLC and osmometry, respectively. During 4 h of rehydration, cumulative urine volumes differed significantly between treatment groups ( p < 0.05) with 4.9, 2.2, and 3.4 mL from water‐, milk‐, and MPS‐fed rats, respectively. Thus, MPS elicited 50% of total body fluid retention of milk. Plasma aldosterone levels were significantly higher in MPS‐and milk‐fed rats compared to water‐fed rats. Plasma osmolality was maintained at higher levels in MPS‐fed rats than in water and MES‐fed rats ( p < 0.05). Cumulative urine sodium excretion was also suppressed in the milk‐and MPS‐fed groups compared to the MES‐fed group. Our results demonstrate that MPS obtained by dialysis clearly affects net body water balance. This effect was attributed to retention of sodium and water, and maintenance of plasma osmolality.