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目的 探讨老年大鼠心肌肌浆网 (SR)钙转运的改变及其在心脏收缩功能障碍中的作用。 方法 测定老年和成年Wistar大鼠心功能 ,取左心室肌组织制备肌浆网膜 ,采用Millipore滤过法测定心肌SRCa2 + 摄取、Ca2 + 释放和 3 H Ryanodine受体结合 ,并测定心肌SRCa2 + ATP酶活性。 结果 与成年组比较 ,老年组大鼠左室舒张末压 (LVEDP)升高 82 % (P <0 0 5 ) ,左室内压变化速率(±dp/dt)分别下降 8%和 2 4% (P <0 0 5 ) ;心肌SRCa2 + ATP酶活性〔(6 2 6± 1 2 2 )与 (12 34± 1 46 )μmolPi·mg-1protein·h-1,P <0 0 5〕与Ca2 + 摄取量〔(35 40± 3 5 7)与 (72 6 2± 8 10 )nmolCa2 + ·mg-1protein·min-1,P <0 0 5〕明显下降 ;老年心肌SR3 H Ryanodine受体结合最大值降低 37% (P <0 0 5 ) ,解离常数 (Kd)值无明显变化 ,且心肌SRCa2 + 释放速率明显降低〔(12 5 0± 2 2 9)与 (17 6 5± 1 93)nmolCa2 + ·mg 1protein·15s-1,P <0 0 5〕。 结论 老年大鼠心脏收缩功能下降 ,其机制涉及心肌SRCa2 + ATP酶活性降低所致的Ca2 + 摄取下降 ,及SR3 H Ryanodine受体结合量下降所致的Ca2 + 释放功能障碍。
Objective To investigate the changes of calcium transport in sarcoplasmic reticulum (SR) and its role in cardiac systolic dysfunction in aged rats. Methods The cardiac function of aged and adult Wistar rats was measured. The sarcoplasmic reticulum was prepared from the left ventricular muscle. The myocardial SRCa2 + uptake, Ca2 + release and 3HRanodine receptor binding were measured by Millipore filtration. The levels of SRCa2 + ATP Enzyme activity. Results Compared with the adult group, left ventricular end-diastolic pressure (LVEDP) increased 82% (P <0 05) and left ventricular pressure increased ± 8% and 24% P <0.05). The activities of SRCa2 + ATPase in myocardium [(62 6 ± 1 2 2) and (12 34 ± 1 46) μmol Pi · mg-1 protein · h- (35 40 ± 3 57) and (72 6 2 ± 8 10) nmolCa2 + · mg-1 protein · min-1, P 0 05, respectively. The maximal SR3 H Ryanodine receptor binding (P <0 05), Kd value did not change significantly, and the release rate of SRCa2 + in myocardium was significantly lower than that of [(125 ± 2 2 9) and (1765 ± 1 93) nmol Ca2 + · Mg 1protein · 15s-1, P <0 0 5〕. Conclusion The cardiac contractile function of senile rats is decreased. The mechanism is related to the decrease of Ca2 + uptake induced by the decrease of SRCa2 + ATPase activity in myocardium and the Ca2 + release dysfunction induced by the decrease of SR3 H Ryanodine receptor binding.