FUNCTION OF THE SARCOPLASMIC-RETICULUM AND EXPRESSION OF ITS CA-2+-ATPASE GENE IN PRESSURE OVERLOAD-INDUCED CARDIAC-HYPERTROPHY IN THE RAT
FUNCTION OF THE SARCOPLASMIC-RETICULUM AND EXPRESSION OF ITS CA-2+-ATPASE GENE IN PRESSURE OVERLOAD-INDUCED CARDIAC-HYPERTROPHY IN THE RAT
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DOI：
10.1161/01.res.66.2.554
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发表时间：
1990-02-01
影响因子：
20.1
通讯作者：
LOMPRE, AM
中科院分区：
文献类型：
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作者：
DELABASTIE, D;LEVITSKY, D;LOMPRE, AM
在舒张和舒张期间Ca2+浓度的降低在正常心脏和继发于压力过载的肥厚心脏中发生不同。我们通过检查肌浆网的功能和编码其Ca2(+)- atp酶的基因表达，在腹主动脉收缩引起的轻度和重度代偿性肥厚大鼠心脏中研究了这些差异的一些可能的分子机制。术后1个月对12只假手术大鼠和31只手术大鼠进行研究。18只动物表现为轻度肥厚（左心室wt/体wt小于2.6），13只动物表现为重度肥厚（左心室wt/体wt大于2.6）。在肥厚期间，我们观察到肌浆网功能的下降，通过左心室均质液中草酸刺激的Ca2+摄取来评估。数值从假手术大鼠的12.1 +/- 1.2 nmol Ca2+/mg protein/min下降到轻度和重度肥厚大鼠的9.1 +/- 1.5和6.7 +/- 1.1（与假手术相比，p分别小于0.001和p小于0.001）。这种减少伴随着功能活跃的CA2(+)- atp酶分子数量的平行减少，由CA2（+）依赖性磷酸化中间体的水平决定：轻度和重度肥厚中分别为58.8 +/- 7.4和48.1 +/- 13.5 pmol P/mg蛋白，而假药中为69.7 +/- 8.2 （P < 0.05和P < 0.01，分别与假药相比）。利用S1核酸酶作图，我们观察到假手术和肥大心脏的Ca2(+)- atp酶信使RNA （mRNA）是相同的。最后，利用互补DNA克隆和肌浆网Ca2(+)- atp酶特异性单克隆抗体，通过点印迹分析研究Ca2(+)- atp酶基因在mRNA和蛋白水平上的相对表达水平。在轻度肥厚中，左心室Ca2(+)- atp酶mRNA和蛋白浓度与假手术组相比没有变化（mRNA, 93.8 +/- 10.6%，假手术组，NS；蛋白，105.5 +/- 14%，假手术组，NS）。重度肥厚时，Ca2(+)- atpase mRNA和蛋白浓度分别降至68.7 +/- 12.9%和80.1 +/- 15.5% (p < 0.001和p < 0.05)，而每左心室mRNA和酶的总量没有变化或略有增加。严重肥厚心脏的缓慢松弛速度至少可以部分解释为Ca2(+)- atp酶基因表达的缺乏增加和Ca2+泵密度的相对减少。（摘要删节为400字）
The reduction in Ca2+ concentration during diastole and relaxation occurs differently in normal hearts and in hypertrophied hearts secondary to pressure overload. We have studied some possible molecular mechanisms underlying these differences by examining the function of the sarcoplasmic reticulum and the expression of the gene encoding its Ca2(+)-ATPase in rat hearts with mild and severe compensatory hypertrophy induced by abdominal aortic constriction. Twelve sham-operated rats and 31 operated rats were studied 1 month after surgery. Eighteen animals exhibited mild hypertrophy (left ventricular wt/body wt less than 2.6) and 13 animals severe hypertrophy (left ventricular wt/body wt greater than 2.6). During hypertrophy we observed a decline in the function of the sarcoplasmic reticulum as assessed by the oxalate-stimulated Ca2+ uptake of homogenates of the left ventricle. Values decreased from 12.1 +/- 1.2 nmol Ca2+/mg protein/min in sham-operated rats to 9.1 +/- 1.5 and 6.7 +/- 1.1 in rats with mild and severe hypertrophy, respectively (p less than 0.001 and p less than 0.001, respectively, vs. shams). This decrease was accompanied by a parallel reduction in the number of functionally active CA2(+)-ATPase molecules, as determined by the level of Ca2(+)-dependent phosphorylated intermediate: 58.8 +/- 7.4 and 48.1 +/- 13.5 pmol P/mg protein in mild and severe hypertrophy, respectively, compared with 69.7 +/- 8.2 in shams (p less than 0.05 and p less than 0.01, respectively, vs. shams). Using S1 nuclease mapping, we observed that the Ca2(+)-ATPase messenger RNA (mRNA) from sham-operated and hypertrophied hearts was identical. Finally, the relative level of expression of the Ca2(+)-ATPase gene was studied by dot blot analysis at both the mRNA and protein levels using complementary DNA clones and a monoclonal antibody specific to the sarcoplasmic reticulum Ca2(+)-ATPase. In mild hypertrophy, the concentrations of Ca2(+)-ATPase mRNA and protein in the left ventricle were unchanged when compared with shams (mRNA, 93.8 +/- 10.6% vs. sham, NS; protein, 105.5 +/- 14% vs. sham, NS). in severe hypertrophy, the concentration of Ca2(+)-ATPase mRNA decreased to 68.7 +/- 12.9% and that of protein to 80.1 +/- 15.5% (p less than 0.001 and p less than 0.05, respectively), whereas the total amount of mRNA and enzyme per left ventricle was either unchanged or slightly increased. The slow velocity of relaxation of severely hypertrophied heart can be at least partially explained by the absence of an increase in the expression of the Ca2(+)-ATPase gene and by the relative diminution in the density of the Ca2+ pumps.(ABSTRACT TRUNCATED AT 400 WORDS)