RehydrationEnhanced renal Na+ reabsorption by carbohydrates in beverages during
restitution from thermal and exercise-induced dehydration in men
Kamijo YI, Ikegawa S, Okada Y, Masuki S, Okazaki K, Uchida K, Sakurai M, Nose H
Am J Physiol Regul Integr Comp Physiol 2012; 303: R824-R833
We studied whether the carbohydrates in an ion supply drink accelerated fluid retention during recovery from dehydration following exercise. In addition, we examined whether this was caused by an enhanced renal sodium reabsorption due to insulin secretion.
Seven healthy young male subjects performed three cross-over designed trials using ion supply drinks A, B and C that had carbohydrate concentrations of 6.5g/dl, 3.3g/dl and 0.0g/dl, respectively, and electrolyte concentrations of 49mg/dl [Na+] and 20mg/dl [K+]. After dehydration by 2.3% of the body weight due to cycle ergometer exercise in a hot environment (ambient temperature 36.0℃, relative humidity 30%), the subjects drank the same amount of beverage as the body weight loss within 30 minutes, then blood and urine samples were collected every 30 minutes.
A significant difference in the plasma volume recovery was observed between ion supply drinks A or B and ion supply drink C until 75 minutes after exercise, and between ion supply drink A and ion supply drinks B or C at 135 minutes, and between ion supply drink A and ion supply drink B at 165 minutes. A significant difference in the rate of renal sodium reabsorption was observed between subjects who received ion supply drink A and ion supply drink C from 15 to 105 minutes after exercise and between ion supply B and ion supply drink C at 45 and 75 minutes after exercise.
The carbohydrates in an ion supply drink could accelerate the recovery of the plasma volume by stimulating insulin secretion and augmenting the renal sodium reabsorption.
Change in plasma volume
Changes in renal Na+ reabsorption rate
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