The cardiac atria secrets polypeptide hormones usually called natriuretic peptides (NPs). These substances play a relevant role in the blood pressure regulation. The objective of the study was to estimate the effects of aging on the secretory apparatus of NPs in cardiomyocytes of the right atrium. Twenty male Wistar rats were studied: 10 young animals aged 3 months old (237 ± 27 g; mean ± SD) and 10 old animals aged 20 months old (450 ± 68 g; mean ± SD). The systolic blood pressure was verified instants before the moment of the euthanasia. Electron micrographs were prepared to quantify the area and density of the NP granules and the relative volumes of the endoplasmic reticulum, Golgi complex, and mitochondria. In addition, the number of pores per 10 μm of karyotheca was another variable evaluated. The significance of the results between the two groups evaluated was analyzed by the Studentʼs t test (p < 0.05). The cardiomyocytes obtained from animals of the old group showed decreased in sectional area and density of secretory granules of NP and lower relative volume of endoplasmic reticulum, Golgi complex, and mitochondria compared with the young rats. Moreover, the quantitative density of nuclear pores was significantly lower compared with the youngers.

Conclusion

Aging causes hypotrophy of the cardiomyocytes of right atrium, similar to what occurs in ventricular cardiomyocytes.

中文翻译：

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衰老对大鼠右心房心肌细胞分泌装置的影响。

心脏心房分泌通常称为利钠肽（NP）的多肽激素。这些物质在血压调节中起着重要作用。这项研究的目的是评估衰老对右心房心肌细胞中NPs分泌装置的影响。研究了20只雄性Wistar大鼠：10只3个月大的小动物（237±27 g；平均值±SD）和10只20个月大的老动物（450±68 g；平均值±SD）。在安乐死时刻之前即刻检查收缩压。制备电子显微照片以量化NP颗粒的面积和密度以及内质网，高尔基复合体和线粒体的相对体积。此外，每10μm核生果的孔数是另一个评估变量。t检验（p <0.05）。与年轻大鼠相比，从老年组动物获得的心肌细胞的横截面积和NP分泌颗粒密度降低，内质网，高尔基复合体和线粒体的相对体积降低。此外，与年轻人相比，核孔的定量密度明显更低。

结论

衰老引起右心房心肌细胞的肥大，类似于在心室心肌细胞中发生的情况。