Abstract: Concentrations of three hormones,and ions and osmotic pressure were measured in serum of rainbow trout Oncorhynchus mykiss during seawater acclimation in different salinities（0,8,16,24,and 32） for 4 hours and 96 hours.The fish had the minimum serum osmotic pressure when exposed to freshwater,but significant increase just when exposed to a salinity of 8 and 16,decrease appreciably later on.There was decline in osmotic pressure in the fish exposed to a salinity of 24,and then in a same case in the fish exposed to a salinity of 32,finally stabilized at（327.0±2.7） mOsm/kg.Rainbow trout transferred from freshwater into seawater showed increase in serum cortisol levels,but decrease at a salinity of 24.Serum T3 concentration was found decrease in the rainbow trout exposed to high salinity.On the contrary,the fish exposed to a salinity of 16 had the minimum T4 content,and then had increase all the time.The Na＋ and Cl-concentrations in serum was found to be increased significantly with the ascending salinity.K＋ concentration was found to be sharply reduced in the 4th hour in salinity 8,and then rose in 96th hours in the fish exposed to the same salinity.Afterward K＋ concentration rose to the maximum value in salinity 24,followed by dropping to the minimum（1.14± 0.15） mmol/L in salinity 32.The Ca2＋ was same as K＋ in salinity from 0 to 16,but after salinity 24 exposure,Ca2＋ concentrations ascended right until the maximum values（3.39±0.01） mmol/L was observed in the 96th hours in a salinity of 32.Except that Ca2＋K＋ in salinity 32,the concentrations of four kinds of ions in rainbow trout serum in different salinities were in sequence as： Na＋Cl-K＋ Ca2＋.It can be concluded that rainbow trout can rapidly activate the adjustment mechanism of osmotic pressure to change the osmolarity in serum in the hypertonic environment,and enhance high-salinity adaptation capacity under the combined effects of several hormones（cortisol,T3,and T4）.
班红琴, 吴垠, 李阳, 付鑫, 宋晶. 盐度驯化过程中虹鳟血清渗透压、激素水平及离子组成的变化[J]. 大连海洋大学学报, 2010, 25(6): 551-555.
BAN Hong-qin, WU Yin, LI Yang, FU Xin, SONG Jing. The changes in osmotic pressure,concentrations of hormones,and ion composition in serum of rainbow trout during salinity acclimation. Journal of Dalian Ocean University, 2010, 25(6): 551-555.
2010, Vol. 25 
