Rumyantsev P P, Borisov A
Institute of Cytology, Acad. Sci. USSR, Leningrad.
Biomed Biochim Acta. 1987;46(8-9):S610-5.
Following 30 repeated 3H-thymidine (3HTdr) injections to rats beginning from days 13 and 21 after birth ca. 20 and 10% of labeled nuclei were observed in the left and right atria, respectively, while in both ventricles cumulative labeling of myocytes was nearly ten times lower. In rats of the same age with experimental myocardial infarction of the left ventricle the number of myonuclei labeled after 30-fold 3HTdr injections increased in atria up to 40-50%, in the perinecrotic area of the left ventricle up to 8-11% and in myofibers of the left and right ventricles located far from the necrotic focus up to 3-4 and 2-3%, respectively. In some of the rats subendocardial and/or subepicardial layers of the surviving left ventricular tissue contained up to 15-35% of labeled myonuclei. Thus, the reproduction capacity of ventricular myocytes in neonates is significantly higher than in adults. Reactive proliferation of cardiomyocytes in the atria of young rats, as opposed to adults, starts on day 3 rather than day 5 after infarction, however the DNA synthesis reactivation is of the same order as found in similar experiments on adult rats. The cultivation in vitro does not eliminate the specificity of the atrial myocytes behavior, their proliferation intensity being 5-7 times higher than that of ventricular ones. Active DNA synthesis and subsequent acytokinetic mitoses of atrial myocytes lead to a significant increase in the number of binucleated cells both after infarction and in vitro.
从出生后第13天和第21天开始，对大鼠进行30次重复的3H-胸腺嘧啶核苷（3HTdr）注射后，分别在左心房和右心房观察到约20%和10%的标记核，而在两个心室中，心肌细胞的累积标记率几乎低10倍。在同龄的左心室实验性心肌梗死大鼠中，30次3HTdr注射后标记的肌核数量在心房中增加到40%-50%，在左心室坏死周边区域增加到8%-11%，在远离坏死灶的左、右心室肌纤维中分别增加到3%-4%和2%-3%。在一些大鼠中，存活的左心室组织的心内膜下和/或心外膜下层含有高达15%-35%的标记肌核。因此，新生儿心室肌细胞的增殖能力明显高于成年人。与成年大鼠不同，幼鼠心房中心肌细胞的反应性增殖在梗死后第3天而非第5天开始，然而DNA合成的重新激活与成年大鼠类似实验中的情况相同。体外培养并未消除心房肌细胞行为的特异性，其增殖强度比心室肌细胞高5-7倍。心房肌细胞活跃的DNA合成及随后的无胞质分裂导致梗死后和体外双核细胞数量显著增加。
