Antagonistic Effects Of Water Calcium On Cadmium Accumulation In Grass Carp (Ctenopharyngodon Idellus)

Cadmium?Cd?is an nonessential mental elements to animals,it cannot be use or absorbed by organism,but poisonous,easily accumulate and hard to eliminate in the body.In contrast to cadmium,Calcium?Ca?is an essential elements to animals,an important constituent part of maintaining body structure and function,lake of it will triggering a series of physiological disorder issues and even leading the occurrence of disease.Studies have proved that Cd can cause toxicity by effect the metabolism of Ca,at the same time,Ca also showed an antagonistic effects to Cd.Presently,the mechanism of organism effected by single metal Ca or Cd has already been introduced comprehensively,but the mechanism of joint effect among metals still needs a further study.The aim of this study was to discuss in the low Cd?0.01mg/L?polluted water,the effect of Ca on the toxicity of Cd on Grass Carp,the results might given some references to the integrate control of heavy metal polluted fishery water.The experiment set three treatments:0,30 and 90mg/L Ca.Each treatments has three parallel groups,no death occurred in a month while the Grass Carp was cultured.After a month,measuring the length and weight of the fish and detecting the concentration of Cd in different tissues?blood,gill,intestine,liver,kidney and muscle??plasma ion concentration?Na⁺?K⁺?Cl^-??antioxidant enzymes?Peroxidant POD;Catalase CAT;Total Superoxide dismutase T-SOD;Malondialdehyde MDA?in muscle and liver?ATPase activities in gill and the expession of ATPase mRNA gene in gill.The main results shown as following:1.Adding different concentration Ca into minor Cd polluted water wound not effect the growth of Grass carp.The distribute of Cd accumulation in different tissues among three treatments were all the same,sequencing in a decreasing order was gut>gill>kidney>liver>muscle.With the increasing of the Ca²⁺,the accumulation of Cd in gill,kidney and liver decreased obviously?p<0.05?.2.Ca can effects the plasma ion composition in minor Cd polluted water,the concentration of Na⁺?K⁺?Cl^-in control group were significantly higher than Cd-Ca combination group?p<0.05?.Na⁺and Cl^-in low Ca group and high Ca group has no significant change?p>0.05?,but K⁺in high Ca group is remarkably higher than low Ca group?p<0.01?.3.Adding different concentration Ca into minor Cd polluted water wound not effect the activity of POD in muscle?p>0.05?,liver POD activity significant higher than control and low Ca groups?p<0.01?.Muscle T-SOD activity extremely higher than other groups?p<0.01?;in liver,high Ca group obviously higher than control group while the low Ca group reverse?p<0.01?.CAT in muscle decreased clearly while Ca increased?p<0.05?;liver CAT in low Ca group significantly higher than others?p<0.01?.Ca can reduce MDA in muscle?p<0.01?,liver MDA in high Ca group significantly higher than control group and low Ca group?p<0.01?.4.The activity change of Na⁺/K⁺-ATPase and Ca²⁺-ATPase in the gill of Grass Carp among treatments was clearly significant?p<0.01?,also decreasing in a same trends.The highest shown in low Ca group,control group second,high Ca group lowest.Even thought the difference between control group and low Ca group was obvious,but the value between them did not exceed 0.8?molPi/prot/h,while the value between control group and high Ca group was almost 2?molPi/prot/h.It reflect that by adding 30mg/L Ca into the Cd 0.01mg/L water can increase the activity of ATPase to some extent?p<0.01?,however adding 90 mg/L Ca will inhibit the activity of ATPase in a great extent?p<0.01?.5.The expression of Na⁺/K⁺-ATPase and Ca²⁺-ATPase mRNA gene in the gill were uncoordinated with ATPase activities,but the highest value were both found in low Ca group.High Ca group ATPase significantly high than low Ca group?p<0.01?,but the mRNA expression in high Ca group was slightly higher than low Ca group,no significant difference exist?p>0.05?.This result proved again that adding 30mg/L Ca into Cd 0.01mg/L water will effectively enhance the ATPase activity and mRNA expression in gene level,but if Ca was added excessively?90mg/L?,the activity of ATPase decreased and the expression also inhibited.