Influence Of Dexamethasone And Fructose-1, 6-Diphosphate On Myocardial Enzymology And Ultrastructure Of Myocardial Cells In Endotoxemia Rats

Objective To explore the protective effect of dexamethasone and fructose-1,6-diphosphate on cTnI and CK-MB and ultrastructure of myocardial cells in rats with endotoxemia.Method Eighty adult maleness Sprague-Dawley(SD)rats were randomized divide into four groups: A group(NS group, 4 subgroups, n= 2), B group(LPS group, 4 subgroups, n=6), C group(DXM group, 4 subgroups, n= 6), D group(FDP group, 4 subgroups, n= 6). LPS group administered to endotoxin(5mg/kg, dissolved by 1ml NS, ip), and NS group controlled with 1ml NS(ip), then they were sacrificed at 6, 12, 24 and 72 hours after injection. The rats in DXM group and FDP group received LPS(5 mg/kg, ip), after one hour, each group received dexamethasone(5 mg/kg, ip)and fructose-1,6-diphosphate(1g/kg, ip). Then they were sacrificed at 6, 12, 24 and 72 hours after injection. After treatment, three milliliters abdominal aorta blood were collected to measure serum cardiac troponin-I(cTnI)and creatine kinase isoenzymes MB(CK-MB); transmural blocks of myocardial tissue from the middle portion of the left ventricular free wall were collected and fixed in formalin. Then myocardiac tissue injury were observed using electron microscopy and light microscopy. Result In LPS group, the serum concentrations of cTnI and CK-MB increased from LPS 6h group(cTnI were 0.445±0.171μg/L and CK-MB were 437.833±103.153U/L), and there is statistical significance compared to NS group(cTnI were 0.018±0.008μg/L and CK-MB were 80.500±7.778U/L, P<0.05). With time goes by, the concentrations advancing, LPS 24h group came to the peak amplitude(cTnI were 5.391±1.262μg/L and CK-MB were 1170.833±169.228 U/L, P<0.01), LPS 72h group were much higher than NS group(cTnI were 3.710±0.813μg/L and CK-MB were 506.167±90.385U/L, P<0.01), even though a litter decreased. In both dexamethasone group and fructose-1,6-diphosphate group, the serum concentrations of cTnI and CK-MB were significantly lower than LPS group in each phase point(the cTnI in each phase point of DXM group were 0.302±0.079μg/L, 1.592±0.537μg/L, 3.132±0.712μg/L, 1.985±0.291μg/L, P<0.05; the CK-MB in each phase point of DXM group were 286.333±102.234U/L, 481.500±78.243U/L, 842.667±137.092U/L, 345.333±71.046U/L, P<0.05; the cTnI in each phase point of PDP group were 0.259±0.050μg/L, 1.277±0.439μg/L, 2.525±0.518μg/L, 2.034±0.227μg/L, P<0.05; the CK-MB in each phase point of PDP group were 231.833±71.522 U/L, 364.167±71.303 U/L, 848.833±160.623 U/L, 322.500±71.643 U/L, P<0.01). But both the DXM and FDP groups were much higher than NS group in each phase point(P<0.01). The DXM group compared with FDP group, they were not statistically significant(P>0.05)except the serum concentrations of CK-MB in 12h subgroups(F =27.447, P<0.05). In LPS 6h group, the morphologic change of myocardiac tissue injury was obviously observed with light microscopy, the ultrastructure was observed with electron microscopy, the mitochondria cristae were disrupted, chaotic and dissolved; concentration, margination and fragmentation were found in the nuclear chromatin. With time goes by, the pathologic damage were evolving. These changes were milder in each phase point of DXM group and FDP group which were compared with that in LPS group both with light microscopy and electron microscopy, the degree of these changes were much obvious with time goes by, and FDP group is much better than DXM group from the aspect of amelioration on myocardial morphology. The morphologic changes of myocardial cells were nearly normal in DXM72h group and were normal in FDP72h group observing with electron microscopy.Conclusion This study verificated that there were myocardial damages in endotoxemia rats, and with time goes by, the damages were aggravated. Dexamethasone and fructose-1,6-diphosphate could relieve the myocardial damages in endotoxemia rats, the protection was more and more obvious as time prolonges. Dexamethasone compared with fructose-1,6-diphosphate, they were no obvious difference from the aspect of myocardial enzymology, but the latter is much better than the former from the aspect of amelioration on myocardial morphology.