| The First Part The Appropriate Dose of"KVP"Cardioplegic Solution protecting Immature Ischemic MyocaidiumObjective To observe the protective effects of"KVP"cardioplegic solution including verapamil and propanolol of different doses and approach their appropriate doses. Methords The Langendorff- perfused isolated rat hearts, 37℃"KVP"cardioplegic solution arrested for 3min and then undergone ischemia for 27min(×3,90min) and reperfusion for 60min,were used for the models of ischemia-reperfusion injury"KVP"cardioplegic solution common temperature protection. The concentration(mol/L) of verapamil and propanolol were 2.0×10-6,3.4×10-7;6.8×10-7,1.1×10-7;2.0×10-7,3.4×10-8.We observed functional indexes including heart rate, tension, contraction force, peak systolic velocity, peak diastole velocity, coronary flow. Results Tension of the hearts was the lowest during ischemia and the beat of the hearts was best during reperfusion in middle dose group. Conclusions"KVP"cardioplegic solution including verapamil 6.8×10-7mol/L, propanolol,1.1×10-7mol/L was appropriate for immature myocardium.The Second Part The Effect of"KVP"Cardioplegic Solution on Immature Ischemic MyocaidiumObjective To evaluate the effect of"KVP"cardioplegic solution on immature ischemic myocaidium and compare it with ST.Thomas'II cardioplegic solution. Methords The 37℃Langendorff- perfused isolated rat hearts were divided into normal perfusion group(perfused for 170min consecutively), ischemia/reperfusion group, ST.Thomas group,"KVP"group(during ischemia, respectively perfused with Locke'solution without oxygen and glucose, ST.Thomas'II cardioplegic solution,"KVP"cardioplegic solution for 3min,reperfusion for 60min).We observed functional indexes. After the experiments, the hearts were used to measure biochemical indexes included Na+-K+ ATPase ,superoxide dismutase, malondialdehyde; observe myocardial histopathology and ultralstructure. Results"KVP"cardioplegic solution including appropriate dose of verapamil6.8×10-7 mol/L, propanolol 1.1×10-7mol/L attenuated immature ischemic myocardial tension,did not delay beating of heart,enhanced coronary flow;avoided energy consumption,enhanced antioxigy ;ensured myocardial integrality. Conclusions"KVP"cardioplegic solution including appropriate dose of verapamil and propanolol possessed better protective effects on immature ischemic myocardium than ST.Thomas'II cardioplegic solution.
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