急性盐度胁迫对卵形鲳鲹幼鱼Na~+-K~+-ATP酶活性和渗透压的影响

研究了水环境急性盐度胁迫对卵形鲳鲹(Trachinotus ovatus)幼鱼鳃Na+-K+-ATP(NKA)酶活力,血清、鳃丝和肾脏渗透压的影响.结果表明:将幼鱼从盐度30(对照)中直接转移至盐度5、10、15、20、25、35水体中,96 h后无死亡.各盐度处理组的鳃NKA酶活性和血清渗透压在最初72 h内出现一定波动,随后变化平稳.试验结束时(96 h),NKA活性随盐度梯度呈"U"型分布,盐度35处理的酶活高于其他处理,盐度20处理活性最低.各处理的血清渗透压大小在96 h时,随着盐度的变化,以盐度15、20为中心,呈对称变化,在盐度20后随盐度上升呈先上升后下降的趋势.相同盐度的鳃渗透压随时间变化呈先上升后下降逐渐稳定的趋势.肾渗透压除盐度5、10处理外,其他盐度组随时间没有显著变化,维持一定的稳定性.说明卵形鲳鲹幼鱼在生理上具有广盐性鱼类的"高渗环境高NKA活性"特征,有较强的渗透压调节与平衡能力.

Effects of acute salinity stress on Na+ -K+ -ATP and osmotic pressure of juvenile Trachinotus ovatus

Effects of acute salinity changes on the gill Na＋-K＋-ATP（NKA） activities,survival rates,and the osmolality of serum,gill,and kidney of juvenile Trachinotus ovatus were measured at 24,48 and 96 h intervals after transferring the juvenile from salinity 30（as control） to salinity 5,10,15,20,25 and 35,respectively.No mortality occurred in all treatments in 96 h.During the experiment the gill NKA activity and serum osmolality fluctuated in first 72 h and then went on smoothly.The NKA activity varied with salinity gradients in U shape,being higher in salinity 35 and the lowest in salinity 20 at 96 h.Changed with salinities the serum osmolality,centering at salinity 15 and 20,showed symmetrical change and it rose first and went down after salinity 20 at 96 h.At same salinity,the change of gill osmolality showed a trend rising first before downward to stabilize gradually.Except at salinity 5 and 10,kidney osmolality had no significant change over time and it kept certain stability in the other groups.It is concluded that T.ovatus could be characterized physiologically as a ＂higher NKA-in-hyperosmotic media＂ marine euryhaline teleost capable of rapid and effective balancing its osmoregulation.