BIOCHEMISTRY OF THE SPONTANEOUSLY HYPERTENSIVE RATS

分离肌浆网（SR）中富集的膜组分 10个月大容易自发中风的婴儿 高血压大鼠（SHRSP），已维持9个月的一个 四种实验饮食：低蛋白（LP）（19%蛋白），标准（STD） (24%蛋白质）、高蛋白质（HP）（32%蛋白质）或高蛋氨酸（1.9% 蛋氨酸）（MET）。 ATP酶活性，以及ATP依赖的Ca 2 + 结合和Ca 2 +-摄取活性，分离的SR被确定为 观察饮食对心肌钙泵活性的影响。 SR从 四组的Mg ~（2+）-ATPase活性相似。 但Ca 2+浓度 + 结果表明，大鼠SR中Mg ~（2+）-ATP酶活性明显高于对照组。 MET饲料中的活性，而其他组中的活性不显著 差异 孵育15秒后，Ca 2 +-摄取（存在 LP组SR中的草酸盐）显著低于LP组SR中的Ca 2+摄取。 来自其他三个饮食组的SR。 Ca 2+结合（不存在 LP组SR中的草酸盐）也显著低于 其他三个饮食组中的每一个。 SR的动力学分析 60秒内的Ca 2+摄取显示MET组的Bmax为 显著高于STD饮食组的Bmax。 此外该 LP组的Bmax显著低于HP和MET组的Bmax 组 SR的亲和力无显著差异 四个日粮组的钙摄取系统。 这些结果表明 膳食蛋白质的改变可影响心肌肌浆网钙泵 功能

Membrane fractions enriched in sarcoplasmic reticulum (SR) were isolated from the cardiac ventricles of 10-month-old, stroke-prone spontaneously hypertensive rats (SHRSP) which had been maintained for nine months on one of four experimental diets: low protein (LP) (19% protein), standard (STD) (24% protein), high protein (HP) (32% protein), or high methionine (1.9% methionine) (MET). ATPase activities, as well as ATP-dependent Ca2+ binding and Ca2+-uptake activities, of the isolated SR were determined to examine the influence of diet on myocardial Ca2+-pump activity. SR from all four groups exhibited similar Mg2+-ATPase activity. However, the (Ca2+ + Mg2+)-ATPase activity was significantly elevated in SR from rats on the MET diet while the activity in the other groups showed no significant differences. After 15 sec of incubation, Ca2+- uptake (presence of oxalate) in SR from the LP group was significantly less than Ca2+-uptake in SR from each of the three other diet groups. Ca2+ binding (absence of oxalate) in the SR from the LP group was also significantly less than that from each of the three other diet groups. Kinetic analysis of SR Ca2+-uptake over 60 sec revealed that the Bmax of the MET group was significantly higher than Bmax of the STD diet group. In addition, the Bmax of the LP group was significantly lower than Bmax of the HP and MET groups. There was no significant difference in affinity of the SR Ca2+-uptake system among the four diet groups. These results indicate that modification of dietary protein can influence myocardial SR Ca2+-pump function.