Endoxin antagonist up-regulates gene expression of sodium pump isoforms in rats with myocardial ischemia reperfusion injury / 中国病理生理杂志

ABSTRACT

AIM: To observe the effect of endoxin antagonist,anti-digoxin antiserum,on endoxin level,ATPase activities,intramitochondrial total calcium concentration and gene expression of sodium pump isoforms in myocardium of rats with myocardial ischemia reperfusion(MIR).METHODS: Fifty-six male Sprauge Dawley rats were randomly divided into 7 groups.Sham operation group: silk suture threading the left anterior descending coronary artery without ligature;MIR group: left anterior descending coronary artery was subjected to 30 min ligation followed by 45 min reperfusion;normal saline group: MIR model was given 5 mL/kg normal saline;verapamil group: MIR model was given 5 mg/kg verapamil;low dose antidigoxin antiserum group: MIR model was given 8.6 mg/kg antidigoxin antiserum;middle dose antidigoxin antiserum group: MIR model was given 17.3 mg/kg antidigoxin antiserum;high dose antidigoxin antiserum group: MIR model was given 34.5 mg/kg antidigoxin antiserum.All drugs were injected into vessel via femoral vein within 5 min before reperfusion,respectively.After reperfusion,left ventricle myocardium samples were processed immediately in order to measure the activity of Na+-K+-ATPase and Ca2+-Mg2+-ATPase,endoxin level,intramitochondrial total calcium concentration and the experssion of ?1,?2,?3 and ?1 isoforms of sodium pump on mRNA and protein levels by RT-PCR and Western blotting and immunohistochemical assay,respectively.RESULTS: After MIR,the level of endoxin in myocardium was obviously increased.The activities of Na+-K+-ATPase and Ca2+-Mg2+-ATPase in myocardial membrane were significantly decreased while intramitochondrial total calcium concentration increased.The gene expression of the ?1,?2,?3 and ?1 isoforms of sodium pump at both mRNA and protein levels were reduced markedly.Only the effect of verapamil on reducing intramitochondrial total calcium concentration was observed.Antidigoxin antiserum significantly reduced the level of endoxin in myocardium,restored the activities of Na+-K+-ATPase and Ca2+-Mg2+-ATPase,reduced intramitochondrial total calcium concentration,and up-regulated the expression of ?1,?2,?3 and ?1 isoforms of sodium pump at both mRNA and protein levels.CONCLUSION: MIR results in increase of endoxin secretion.The latter depresses the activity of Na+-K+-ATPase by down-regulating the gene expression of ?1,?2,?3 and ?1 isoforms of sodium pump in myocardial membrane,and also induces intramitochondrial calcium overload,thereby mediates MIR injury.