Objective To investigate the protective effects of metallothionein （MT） for immature myocardium and myocardial interstitium.Methods Twenty-four rabbits （aged 14-21 days） were divided into 4 groups with random number table, 6 each group. Distilled water was injected intraperitoneally in control group and 3.6% ZnSO4 （1.5 ml/kg） was injected intraperitoneally in group 1, group 2 and group 3. Control group, group 1, group 2 and group 3 isolated working rabbit heart model were used in 24h, 12h, 24h and 48h after intraperitoneally respectively. The MT content, recovery of hemodynamics, biochemistry and myocardial ultrastructure were tested. Results The MT content, hemodynamics recovery, adenosine triphosphate （ATP） content, superoxide dismutase activity, Ca2＋-ATPase activity, synthesizing ATP activity of mitochondria, hydroxyproline in group 2 and group 3 were higher than those in control group and group 1 （P 〈 0. 01）. The myocardial watery content, creatine kinase and dehydrogenase leakage, malondialdehyde content, endothelin, mitochondrial Ca2＋ content in group 2 and group 3 were lower than those in control group and group 1（P〈0.01）. The myocardial ultrastructure injuries were less in group 2 and group 3 than that in control group and group l. Conclusion This study demonstrates that myocardial MT prolonged expression can be induced by ZnSO4 and the ischemia-reperfusion injury of immature myocardium and myocardial interstitium could be reduced by MT.
Objective To investigate the protection effects of different pH N 2 hydroxyethyl piperazine N′ 2 ethanesulfonic acid (HEPES) Krebs Henseleit (KH) reperfusate solutions on immature myocardium and myocardial interstitium. Methods Isolated perfused Langendorff model from immature rabbit hearts were performed. Twenty four rabbits were divided into control group, ischemia reperfusion group and acidic reperfusate group. The left ventricular function recovery, myocardial water content(MWC), lactate dehydrogenase (LDH) and creatine kinase (CK) leakage, malondialdehyde(MDA) and adenosine triphosphate (ATP) content, superoxide dismutase(SOD) activity , hydroxyproline(HP) and endothelin(ET) content were tested. Results The left ventricular functional recovery, ATP content, SOD activity and HP content in acidic reperfusate group were higher than those of ischemia reperfusion group( P lt;0.05).MWC, MDA content, CK and LDH leakage, and ET content in acidic reperfusate group were lower than those of ischemia reperfusion group( P lt;0.05). Conclusion These results suggest pH paradox might be one of important mechanisms for immature myocardium and myocardial interstitium ischemia reperfusion injury,and acidic perfusate, at the beginning of reperfusion ,might attenuate pH paradox and ameliorate functional recovery in isolated perfused immature rabbit hearts.