Alterations in sarcoplasmic reticulum calcium uptake, relaxation parameters and their responses to beta-adrenergic agonists in the developing rabbit heart.
Alterations in sarcoplasmic reticulum calcium uptake, relaxation parameters and their responses to beta-adrenergic agonists in the developing rabbit heart.
复制标题
发育中的兔心脏中肌浆网钙摄取、松弛参数及其对β-肾上腺素能激动剂的反应的变化。
DOI：
10.1016/0022-2828(95)90005-5
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发表时间：
1995
影响因子：
5
通讯作者：
Kranias,EG
中科院分区：
文献类型：
--
作者：
Szymanska,G;Grupp,IL;Slack,JP;Harrer,JM;Kranias,EG
用胎、4日龄、21日龄和成年兔心脏评价了心肌肌浆网功能的发育性变化，这可能反映了心肌松弛速率的变化及其对β肾上腺素能刺激的反应。与其他年龄组相比，胎心表现出最慢的松弛速率(−、dp/dt)和最低的肌浆网钙泵的Vmax和EC550。这些参数在4天龄、21天龄和成人心脏中是相似的。通过定量免疫印迹分析，胎儿心脏的低生理生化参数反映了肌浆网钙泵及其抑制剂磷蛋白的表达水平降低。胎儿心脏灌流异丙肾上腺素对其松弛参数或钙泵钙的ECS50无明显影响，这与这些心脏表达的低水平磷蛋白的相对水平一致。然而。用异丙肾上腺素灌流4天龄、21天龄和成年大鼠的心脏，各组的舒张率均显著增加。松弛参数的增加与心肌肌浆网钙泵对钙离子的EC50降低有关，这表明磷酸化介导的磷蛋白抑制效应的减轻。这些结果表明，心肌肌浆网钙泵活性水平的发育调节可能反映了心脏松弛参数的变化以及β肾上腺素能激动剂对其的调节。
Developmental changes in cardiac sarcoplasmic reticulum function, which may reflect alterations in the myocardial rate of relaxation and its responses to β-adrenergic stimulation, were assessed using fetal, 4-day-old, 21-day-old and adult rabbit hearts. The fetal hearts exhibited the slowest rate of relaxation ( −dP/dt) and the lowest Vmaxand EC550of the Sarcoplasmic reticulum Ca2+-pump for Ca2+compared to the other age groups. These parameters were similar among the 4-day-old, 21-day-old and adult hearts. The low physiological and biochemical parameters in the fetal hearts reflected reduced levels of expression of the Sarcoplasmic reticulum Ca2+-pump and its inhibitor, phospholamban, assessed by quantitative immunoblotting. lsoproterenol perfusion of fetal hearts had no significant effect on their relaxation parameters or on the ECS50of the Ca2+-pump for Ca2+consistent with the low relative levels of phospholamban expressed in these hearts. However. perfusion of the 4-day-old, 21-day-old and adult hearts with isoproterenol resulted in significant increases in the rates of relaxation of each group. The increases in relaxation parameters were associated with decreases in the EC50of the cardiac Sarcoplasmic reticulum Ca2+-pump for Ca2+, suggesting a phosphorylation-mediated relief of the phospholamban inhibitory effects. These findings indicate that developmental regulation of the levels of the activity of the cardiac sarcoplasmic reticulum Ca2+-pump may reflect alterations in cardiac relaxation parameters and their modulation by β-adrenergic agonists.