Heyliger C E, Prakash A R, McNeill J H
Division of Pharmacology and Toxicology, Faculty of Pharmaceutical Sciences, University of British Columbia, Vancouver, Canada.
Mol Cell Biochem. 1989 Jan 23;85(1):75-9. doi: 10.1007/BF00223516.
Heart failure is common among the elderly and an alteration in myocardial Ca2+ transport is believed to be involved in its depressed contractile performance. Although ATP-dependent sarcoplasmic reticular (SR) Ca2+ transport has been reported to decrease in old hearts, virtually nothing appears to be known about the Ca2+ pump activity of SR in aging myocardium in the presence of calmodulin, one of its endogenous activators. In this study, the activity of the Ca2+ pump of aging cardiac SR was assessed in the presence of this endogenous stimulator. This assessment was therefore designed to give additional information about the status of this enzyme in old hearts. Male Sprague-Dawley rats were used and were divided into 3 groups: young (4-6 months old); middle-aged (15-17 months old) and old age (24-25 months old). Purified SR membranes were isolated from ventricular tissues. ATP-dependent Ca2+ accumulation by membrane vesicles of middle-aged and old hearts was significantly depressed in comparison to young hearts at all Ca2+ concentrations employed in the absence and presence of calmodulin. The activity of this Ca2+ transporter was similar in middle-aged and old hearts even in the presence of calmodulin. These results suggest that the activity of the Ca2+ pump in SR of aging hearts is depressed even in the presence of calmodulin.
心力衰竭在老年人中很常见，心肌钙（Ca2+）转运的改变被认为与其收缩功能降低有关。尽管已有报道称老年心脏中依赖三磷酸腺苷（ATP）的肌浆网（SR）钙转运减少，但在衰老心肌中，在其一种内源性激活剂钙调蛋白存在的情况下，关于SR的钙泵活性几乎一无所知。在本研究中，在这种内源性刺激物存在的情况下评估了衰老心脏SR钙泵的活性。因此，该评估旨在提供有关老年心脏中这种酶状态的更多信息。使用雄性斯普拉格-道利大鼠，并将其分为3组：年轻组（4 - 6个月大）；中年组（15 - 17个月大）和老年组（24 - 25个月大）。从心室组织中分离出纯化的SR膜。在不存在和存在钙调蛋白的情况下，在所有使用的Ca2+浓度下，中年和老年心脏膜囊泡依赖ATP的钙积累与年轻心脏相比均显著降低。即使在存在钙调蛋白的情况下，这种钙转运体的活性在中年和老年心脏中也是相似的。这些结果表明，即使在存在钙调蛋白的情况下，衰老心脏SR中钙泵的活性也会降低。
