Effects of salinity on Na+/K+-ATPase activity,the osmolality of pericardial cavity fluid and peritoneal fluid and ion content in Onchidium struma

Abstract

To explore the effects of salinity on the Na+/K+-ATPase activity,the osmolality of pericardial cavity fluid and peritoneal fluid and ion content(Na+,K+ and Cl-)in Onchidium struma(Objective),six hundred healthy specimens[wet weight(10.24±2.16)g]were selected and had been raised for 30 days with simulated ecological environments in different salinity conditions(5,15,25,35 and 45),then all indices were determined(Method).The results show:(1)The salinity and osmolality of peritoneal fluid and pericardial cavity fluid of O.struma are increased with increasing ambient salinity.The increased amplitude of peritoneal fluid are 25-43 and 514-796 mOsm·/kg respectively,which were greater than the pericardial cavity fluid(23-28 and 502-726 mOsm/kg respectively).(2)The content of Na+,Cl-and K+ of pericardial cavity fluid is consistent with the changes of ambient salinity and these all increased first then decreased.The concentration of Na+,Cl-and K+ reached the maximum at salinity 25,which is 295.50 mmol/L,322.50 mmol/L and 5.15 mmol/L respectively.Besides,salinity has a significant impact in Na+ and Cl-but with no significant effect on K+.(3)There are significant differences on Na+/K+-ATPase activity of different parts in O.struma.The Na+/K+-ATPase in cardia stomach,intestine,epidermis,muscle and pericardial cavity membrane of O.struma have higher activity.In addition,the Na+/K+-ATPase activity of different parts activated by salinity with some tissue-specificity,there are higher activity of cardia stomach and muscle in low salinity while the intestine,kidney and pericardial cavities membrane in high salinity(Result).These results indicate that the salinity can significantly impact the osmolality and ion concentration of peritoneal fluid and pericardial cavity fluid as well as the Na+/K+-ATPase activity of O.struma.The cardiac stomach,intestine and muscle are the main tissues involved in its ion transport and osmoregulation with strong osmotic adjustment capability(Conclusion).