Levitsky D, de la Bastie D, Schwartz K, Lompré A M
INSERM U 127, Hopital Lariboisière, Paris, France.
Am J Physiol. 1991 Oct;261(4 Suppl):23-6. doi: 10.1152/ajplung.1991.261.4.L23.
The properties of the calcium pump system of sarcoplasmic reticulum (SR) were studied in a series of 34 rats subjected to cardiac overload and 19 sham-operated animals. Total homogenates of left ventricle were analyzed by measuring the oxalate-supported Ca2+ uptake rate, the steady-state level of the phosphorylated intermediate of Ca(2+)-adenosine triphosphatase (Ca(2+)-ATPase) (EP), and the amount of Ca(2+)-ATPase mRNA. All three parameters decreased gradually as a function of the relative left ventricular weight increase. The calcium-sensitivity curves showed that the velocity of Ca2+ transport in SR from the hypertrophied heart is diminished at low as well as optimal Ca2+ concentrations, with the dissociation constant (Kd) value for Ca2+ unchanged from that of the control preparation. Taken together with the results presented in our recent publication (De la Bastie, Levitsky, Mercadier, Marotte, Wisnewsky, Brovkovivh, Schwartz, and Lompré, Circ. Res. 66: 554-564, 1990), these data strongly indicate that differences in the Ca2+ pump activities of SR from normal and hypertrophied rat hearts are due to quantitative rather than qualitative changes of the Ca(2+)-ATPase protein.
在34只承受心脏负荷的大鼠和19只假手术动物中，研究了肌浆网（SR）钙泵系统的特性。通过测量草酸盐支持的Ca2+摄取率、Ca(2+)-三磷酸腺苷酶（Ca(2+)-ATPase）磷酸化中间体的稳态水平（EP）以及Ca(2+)-ATPase mRNA的量，对左心室的总匀浆进行了分析。随着左心室相对重量的增加，所有这三个参数均逐渐降低。钙敏感性曲线表明，肥大心脏的SR中Ca2+转运速度在低Ca2+浓度以及最佳Ca2+浓度下均降低，而Ca2+的解离常数（Kd）值与对照制剂相比没有变化。结合我们最近发表的结果（De la Bastie、Levitsky、Mercadier、Marotte、Wisnewsky、Brovkovivh、Schwartz和Lompré，《循环研究》66:554 - 564，1990），这些数据有力地表明，正常和肥大大鼠心脏的SR中Ca2+泵活性的差异是由于Ca(2+)-ATPase蛋白的数量变化而非质量变化所致。
