Osmoregulation involves many aspects of physiological function in crustacean. Crustacean species exhibit almost all possible patterns of osmotic regulation and they are widely distributed in most of known biotopes. With the changes of liquid environment, the structure and function of the osmoregulation organs（such as gills, antennary glands）,haemolymph osmotic pressure and ionic transport will turn to maintain the well-balanced metabolism, which are under the neuroendocrine regulation. The current research status of physiological mechanism of crustacean osmoregulation was reviewed in the following aspects: 1)Structure and function of gills and antennal glands（maxillary glands）. The gills are very important organs and play a prominenet role in osmoregulation; 2)Regulation of ion transport in branchial epithelium. Ion transport enzymes （Na+-K+-ATPase, V-ATPase,HCO3--ATPase and carbonicanhydrase） stimulated by bioamines and cAMP may participate in the ion transport of branchial epithelium in crustacean; 3)Haemolymph composition and osmoregulation. Haemolymph concentration of ion and free amino acid accompanied by metabolites of blood can contribute to the most of haemolymph osmotic pressure; 4)Neuroendocrine control. Many neuropeptides may regulate the osmotic pressure of haemolymph and proteinsases activity of epithelial gill cells. Bioamines, cAMP and CaM have been proved to stimulate the uptake of Na+ and transport of Cl-.
The metallothionein（MT） concentration in hepatopancreas of Litopenaeus vannamei changed significantly with the increasing of metal ions concentration and prolongation of exposure time（P<0.05）,whereas that in the control groups had no marked changes（P>0.05）.Exposed to three heavy metal ions,the MT concentration in hepatopancreas changed very significantly in 6 h（P<0.01）. The MT concentration inducted by Cu2+(0.1,0.2,0.5,1 mg·L-1), Zn2+(1,2, 5 mg·L-1)and Cd2+(0.05,0.1 mg·L-1)increased in 96 h with time and changed stably after 48 h.In addition,the MT concentration inducted by Zn2+(10 mg·L-1) and Cd2+(0.25,0.5 mg·L-1)was up to max.at 48 h,began to decrease with time passing by,and still higher than that in the control groups.Meanwhile the inductive ratio of three heavy metal ions on metallothionein concentration were Cd2+>Cu2+>Zn2+ in experimental time.
