Navaratnam V, Woodward J M, Skepper J N
Department of Anatomy, University of Cambridge, England.
J Anat. 1989 Apr;163:261-73.
The ontogenesis of specific heart granules and of the related natriuretic peptide activity in heart muscle was studied in fetal and neonatal rats and golden hamsters by ultrastructural analysis including immunogold labelling for ANP-28 and by radioimmunoassay. In both species, immunoreactive granules first appear in the myocardial sleeve of the embryonic heart tube during the looping stages which precede chamber formation and the peptide becomes detectable by radioimmunoassay two or three days later by which time the chambers are identifiable. Granule density and ANP concentration in the rat are higher than in the hamster at all stages of development. Almost all atrial myocytes express ANP in fetal hearts whereas, in the ventricular wall, cells containing immunoreactive granules are scattered. The density of granules in atrial myocytes increases during further stages of fetal and neonatal development, while it decreases markedly even in those ventricular myocytes which are immunoreactive. Changes in the ultrastructural appearance of ventricular SHG suggest that the mode of production of ANP changes in ventricular myocytes after birth but does not change in atrial cells. There is no correlation between the distribution of immunoreactive ventricular myocytes and that of the conducting system. In both species, the concentration of ANP in the atrial well is higher than ventricular levels from the outset and the disparity becomes exaggerated with development till, in six months old adult animals, the atrial to ventricular concentration ratio is about 3 x 10(3):1 in the rat and 1.5 x 10(3): 1 in the hamster. In the hamster, a distinct gradient of ANP concentration between the right and left atria is already established in the early fetal period and it becomes enhanced in the neonatal period. In the rat, however, a slight difference becomes discernible only after birth.
通过包括抗心钠素 - 28免疫金标记的超微结构分析和放射免疫测定法，对胎鼠和新生大鼠以及金黄地鼠心肌中特异性心脏颗粒的个体发生和相关利钠肽活性进行了研究。在这两个物种中，免疫反应性颗粒首先出现在胚胎心脏管的心肌套中，在腔室形成之前的环化阶段，而肽在两到三天后通过放射免疫测定法可检测到，此时腔室已可识别。在发育的所有阶段，大鼠的颗粒密度和心钠素浓度均高于地鼠。在胎儿心脏中，几乎所有心房肌细胞都表达心钠素，而在心室壁中，含有免疫反应性颗粒的细胞是分散的。在胎儿和新生儿发育的进一步阶段，心房肌细胞中的颗粒密度增加，而即使在那些具有免疫反应性的心室肌细胞中，颗粒密度也明显降低。心室致密核心颗粒超微结构外观的变化表明，出生后心室肌细胞中心钠素的产生方式发生了变化，但心房细胞中没有变化。免疫反应性心室肌细胞的分布与传导系统的分布之间没有相关性。在这两个物种中，心房中的心钠素浓度从一开始就高于心室水平，并且随着发育这种差异变得更加明显，直到在六个月大的成年动物中，大鼠的心房与心室浓度比约为3×10³:1，地鼠为1.5×10³:1。在地鼠中，胎儿早期右心房和左心房之间的心钠素浓度就已经形成明显梯度，并且在新生儿期增强。然而，在大鼠中，只有在出生后才可以看出轻微差异。
