Abstract
Eight male subjects were exposed to heat (36°C, 70% RH) and exercise stress for 2 hours, and plasma volume, hematocrit value, concentration of plasma protein, blood water content, plasma osmolality and concentrations of ions in plasma were determined together with sweat and urine volume and their ionic compositions. These observations were repeated on each subjects three times: without any fluid replacement (dehydration exp.), with free access to tap water (water exp.) and with free access to a glucose-electrolyte solution (G-E exp.) . The results obtained are as follows: 1) The degree of voluntary dehydration was significantly higher in water exp. than in G-E exp. 2) In dehydration exp., significantly higher loss of water in erythrocyte and increase in plasma chloride concentration were observed, which suggest the shift of water from intracellular compartment. 3) Changes in plasma protein concentration, osmolality and water contents in blood showed significantly quick recovery in G-E exp. It is still to be determined whether these differences are due to the difference in the amount of ingestion or due to the quick absorption of glucose-electrolyte solution.
