The effect of dehydration level on the NaCl concentration chosen by rats.
The relationship between the level of dehydration (3%, 6%, and 8% body weight) and the preference for water and saline in the rehydration were assessed in rats for 15 h. At the 6% and 8% dehydration levels, rats provided with tap water and 0.9% NaCl solution simultaneously consumed more water than NaCl solution (calculated Na concentration was about 57 mEq/l) within 3 h and then consumed more NaCl solution than water (about 116 mEq/l). The shift of the Na concentration of fluid occurred when about 107% of lost cations and 82% of lost fluid were regained. Urine output and urinary Na output were about 14% of the ingested fluid during the initial 4 h; after that, the output was in amounts almost equal to the ingestion. However, the 3% dehydrated rats consumed almost equal amount of tap water and NaCl solution (about 68 mEq/l) throughout the 15 h. The result indicates that at more than 3% dehydration level, rats initially choose hypotonic NaCl solution, and the volume loss of body fluid is then regained by the consumption of almost isotonic Na solution.
Department of Physiology, Kyoto Prefectural University of Medicine, Japan.
T
T
Kawabata
T
T
Okuno
T
T
Morimoto
D000818:Animals; D001810:Blood Volume / Q000502:physiology; D004326:Drinking / Q000502:physiology*; D006358:Hot Temperature / Q000009:adverse effects; D008297:Male; D009994:Osmolar Concentration; D051381:Rats; D017208:Rats, Wistar; D012965:Sodium Chloride / Q000008:administration & dosage*; D014882:Water-Electrolyte Balance / Q000502:physiology*; D015431:Weight Loss / Q000502:physiology
D012965:Sodium Chloride