Extracellular space in chickens estimated using sucrose, thiosulfate, and thiocyanate injected concurrently

The extracellular fluid (ECF) volume was estimated in chickens, a species for which remarkably high estimates (usually of thiocyanate space) have been reported. Chickens aged 8 weeks were given a single intravenous injection containing the three extracellular markers, [³H]sucrose, [³⁵S]thiosulfate, and thiocyanate. After allowing 10 min for mixing to occur, plasma samples were obtained at intervals and marker concentrations were measured and used to estimate initial dilution of the markers in ECF. In contrast with most earlier studies, all three markers yielded estimates of ECF volumes that were in the range normally found in mammals. The mean sucrose space (17.8 ml/100 g body wt) was significantly lower than both the thiosulfate space (22.3 ml/100 g) and the thiocyanate space (23.9 ml/100 g).