The Protective Effect Of Astragalus Polysaccharide(APS) On Cardical Dysfunction In Severely Scalded Rabbit

Objective:1.Establishment of acute bum rabbit model, study the lesion of cardiac function in severely scald rabbit.and observe the change rule of the biomarks of myocardial injury(aspartate aminotransferase--AST,Creat-ine kinase--CK,creatine kinase--CK-MB, lactate Dehydrogenase--LDH, Troponin I--cTnI),Oxidation-antioxi-dation property(malondialdehyde--MDA, superoxide dismutase--SOD), active va soconstrictors(Angiotensin II--Ang II, Endothelin-1--CT-1),hemorheological index es as well as myocardial pathology.2.To study the protective effect of astragalus polysaccharides on Cardiac dysfunction in severely scalded rabbit which was early intervened by APS via investigating the changes of the biomarkers of myocardial Injury(AST, CK, CK-MB, LDH, cTnI), oxidation-antioxidation property(MDA, SOD), active vasocon strictors(Ang II, CT-1), hemorheological indexes and myocardial pathology.Methods:64 healthy adult male rabbits were choosed as a subject of the study,which were wighted(2.4±0.2) kg.The rabbits were randomly divided into two groups: Simple burn group(called Model group), scald with astragalus polysaccharide treatment group(called APS group), with 32 rabbits in each group.The rabbits were allowed to acclimate for 1 week, handpicked four rabbits from each group and collected 10 ml venous blood sample from its jugular vein in each rabbit in the pre-injury 1 hour and then tested, the results as the normal reference value.Then each rabbit was depilated and anesthetized,each experimental animal was scalded by the scald apparatus which the temperature was set at 108 ℃, burn time was set to 8 s and the vapor pressure was of 4 Mpa to manufacture into a 30% TBSA III degree scalded model. All the scalded rabbits were immediately given an intraperitoneal injection according to the Parkland’s formula so as to receive the anti-shock treatment after the serious injury. All the animals reared inseparate cages and the wound was smeared with iodophor twice a day. The rabbits of the APS group received an intraperitoneal injection of 200 mg/kg of Astragalus polysaccharide at the time of the moment after burn and at 8 am of the following 6days.while the Model group rabbits received an equal number of 0.9% normal saline instand at the same time-phase, until the animal was executed.Observed and recorded the survival rate of each group. In the 1,3,7,14 thday after scalded, randomly selected 8 rabbits from each group to be anesthetized and then Opened the chest to expose the internal jugular vein and heart in aseptic condition in every time-phase.fistly, collected about 10 ml venous blood from jugular vein and then tested.secondly, sacrificed and harvested its heart, and harvested 100 mg tissue from the left ventricular myocardial,fixed in formalin,embedded in paraffin,Made pathological Section and proceeded HE stain for pathological observation.cut another 100 mg left ventricular myocardial tissue,through the steppes of cleaning, cutting up, grinding to make into supernatants of myocardial cell and then detected.Results:1. The survival rate of each experimental groupThe rabbits of the Model group after scalded showed that three died during12-24 h,two during 24-48 h and 1 in the third day,the mortality occupies 18.75%;The APS group 2 rabbits died in 12-24 h and 1 in 24-48 h, its mortality decreased and only takes up 9.38%. But there was no significant difference of the mortalities becourse of the amount of animals.2. The change of the serum biomarkers of myocardial injury(AST,CK,CKMB,LDH,c TnI)Compared to pre-injury phase: the results of the two groups showed that serum enzyme level of AST,CK,CK-MB,LDH and cTnI all increased greatly after scalded,the LDH level rapidly reached the peak at the third day while another four at the firt day, then declined gradually in turns,and reached to the pre-injury level in the14 thday.Compared in the two groups: the level of CK,LDH and cTnI of the APS group significantly decreased(P<0.05) than the Model group in the 1,3,7th day,but no significant difference in the post-injury 14 th day; the level of AST,CK-MB alsosignificantly decreased(P<0.05) than the Model group in the 1,3th day after injury,but no difference in the 7th and 14 th day.3. The change of the myocardial pathologicalThere were different degree of myocardial structural lesions of the Model group after actue burn. The acute inflammation injuries of cardiomyocytes such as exudation,edema, fatty degeneration and liquefactive necrosis were the chief Manifestation in the 1th and 3th day;while pathological changes of the heart cells could be described as degeneration, hypertrophy and stromal fibrous proliferation in the 7 th and 14 thday.and compared into the two groups,the damage extent of myocardial cells of the APS group had obviously been alleviated than the Model group, especially in the 7th and 14 th day, no significantly hypertrophy and Stromal fibrous proliferation occurred.4. The change of serum oxidation-antioxidation property(MDA,SOD)Compared to pre-injury 1 hour: the serum SOD level of the Model group rised in the post-injury 1 day, decreased sharply in the 3thand 7thday, and no difference in the 14 th day;while the serum MDA level significantly increased(P<0.05) in the1,3,7th day,but no difference in the 14 th day. Compared in the two groups: in the1,3,7thday after scalded,the MDA level of the APS group significantly decreased than the Model group(P<0.05), while the level of SOD significantly increased(P<0.05),but no significant difference of them in the 14 th day.5. The change of serum vasoconstrictors(Ang II,CT-1)Compared to pre-injury 1 hour: the serum Ang II and CT-1 levels of the Model group all abviously raised(P<0.05) in the post-injury time-phases.the serum Ang II level of the APS group increased in the 1thand 3thday after scalded,but quickly recovered in the 7 th day; while the CT-1 level of the APS group raised in the 1,3,7 th day,and recovered in the 14 th day.Compared in the two groups: in all post-injury phases,the Ang II,CT-1 level of the APS group significantly decreased(P<0.05) than the Model group.6. The change of active vasoconstrictors(AngII,CT-1) in myocardialHomogenate compared to the normal rabbit:the level of Ang II,CT-1 in myocar-dial homogenate of the two groups increased sharply after burn, reached the peak at the firt day, then declined gradually in turns,and reached to the pre-injury level in the14 th day. Compared in the two groups: at the same time-phage, the Ang II, CT-1 levels of the APS group significantly decreasedthan the Model group(P<0.05).7. The change of hemorheological indexes(ηb,ηr,ηp,HCT, ESR,EAI,TK)Compared to pre-injury 1 hour: theηb(With the same shear rate),ηr,ηp,HCT,ESR,EAI,TK levels of the Model group all abviously rised(P<0.05) in the 1,3,7th day.the ηb,ηr,ηp,HCT, ESR,EAI,TK levels of the APS group also increased in the 1th and 3th after scalded,but quickly recovered in the 7th day.Compared in the two groups: all the indexes of the APS group significantly decreased than the Model group(P<0.05) in the 1,3,7thday.but no difference in 14 thday.Conclusions:1.There were abnormal changes in different levels of the markers of myocardial injury,oxidation–antioxidation property, active vasoconstrictors, hemorheolo gical indexes and myocardial pathology in severely scalded rabbits. and it was showed that there were different extents of heart injuries occurred after acute scald.2.Through intervened by the astragalus polysaccharide in severely scalded r abbits,the markers of myocardial injury,oxidation– antioxidation property, active vasoconstrictors, hemorheological indexes and myocardial pathology had recov ered at different degrees.which incaditaed astragalus polysaccharide could allevi ate the myocardial damage in the early period of the major burns and has a go od protective effect on its cardiac dysfunction.