MorphologyMorphologyМорфология1026-35432949-2556Eco-Vector63192010.17816/morph.631920Original Study ArticlesОригинальные исследованияResearch ArticleElectron microscopy study of left ventricular cardiomyocytes in adult rats born pretermЭлектронно-микроскопическое исследование кардиомиоцитов левого желудочка половозрелых крыс, рождённых недоношенными性成熟早产大鼠左心室心肌细胞的电子显微镜研究https://orcid.org/0000-0002-2530-11129476-3329IvanovaVera V.ИвановаВера ВладимировнаIvanovaVera V.
Russian Federation

Cand. Sci. (Biology)

канд. биол. наук

Cand. Sci. (Biology)

ivvera92@rambler.ruhttps://orcid.org/0000-0002-9764-43924919-2033MiltoIvan V.МильтоИван ВасильевичMiltoIvan V.
Russian Federation

Dr. Sci. (Biology), Assistant Professor

д-р биол. наук, доцент

Dr. Sci. (Biology), Assistant Professor

milto_bio@mail.ruSiberian State Medical UniversityСибирский государственный медицинский университетSiberian State Medical UniversitySeversk Biophysical Research CenterСеверский биофизический научный центрSeversk Biophysical Research Center2707202404092024162163711305202419062024Copyright ©; 2024, Eco-VectorCopyright ©; 2024, Эко-ВекторCopyright ©; 2024,2024Eco-VectorЭко-Векторhttps://creativecommons.org/licenses/by-nc-nd/4.0/https://j-morphology.com/1026-3543/article/view/631920

BACKGROUND: Preterm birth is a risk factor for the early development of cardiovascular diseases. Thus far, based on the results of clinical studies, the ultrastructural features of cardiomyocytes in adolescents and adults born prematurely can be identified. Thus, experiments aimed at studying the effects of preterm birth on the ultrastructure of cardiomyocytes in the late postnatal period of ontogenesis are relevant.

AIM: To identify the ultrastructural features of left ventricular cardiomyocytes in preterm adult rats.

MATERIALS AND METHODS: The study was conducted on full-term (n=4, pregnancy duration 22 days) and preterm (n=4, pregnancy duration 21 days) male Wistar rats. Preterm labor was induced by mifepristone injection to pregnant rats. Preterm and full-term offspring were removed from the experiment on day 180 of the postnatal period of ontogenesis. Fragments of the left ventricle of the heart of preterm and full-term rats were used for the ultrastructural studies of the cardiomyocytes (electron transmission microscopy). Electron microphotographs of longitudinal sections of contractile cardiomyocytes were used to determine the relative areas of the nucleus, cytoplasm, myofibrils, and mitochondria.

RESULTS: The structure of the cardiomyocytes of preterm and full-term rats on postnatal day 180 was fundamentally similar. However, the relative area of the nuclei of cardiomyocytes in preterm rats was lower (p=0.02), and the relative area of the cytoplasm was higher (p=0.02) than that in full-term animals. Exclusively, in the cytoplasm of preterm rats, perinuclear swelling of the cytoplasm, thinning of myofibrils, and signs of mitochondrial damage, such as destruction of mitochondrial membranes, concentric organization of mitochondrial cristae, and dissociation of mitochondrial clusters, were observed.

CONCLUSION: Preterm birth has chronic negative effects on the ultrastructure of cardiomyocytes. The observed ultrastructural changes lead to the disruption of energy production in the cardiomyocytes in the late postnatal period of ontogenesis of preterm rats.

Обоснование. Преждевременное рождение является фактором риска раннего развития заболеваний сердечно-сосудистой системы. На сегодняшний день по результатам клинических исследований невозможно составить представление о структурных особенностях кардиомиоцитов подростков и взрослых, рождённых недоношенными. Актуальным в этой связи является экспериментальное исследование влияния преждевременного рождения на ультраструктуру кардиомиоцитов в отдалённом постнатальном периоде онтогенеза.

Цель исследования — выявление ультраструктурных особенностей кардиомиоцитов левого желудочка у недоношенных половозрелых крыс.

Материалы и методы. Исследование проведено на доношенных (n=4, продолжительность беременности 22 сут) и недоношенных (n=4, продолжительность беременности 21 сут) самцах крыс линии Вистар. Преждевременные роды стимулировали введением беременным крысам мифепристона. Преждевременно рождённое и доношенное потомство выводили из эксперимента на 180-е сутки постнатального периода онтогенеза. Фрагменты левого желудочка сердца недоношенных и доношенных крыс использовали для ультраструктурного исследования кардиомиоцитов (трансмиссионная электронная микроскопия). На электронограммах продольных срезов сократительных кардиомиоцитов определены относительные площади ядра, цитоплазмы, миофибрилл, митохондрий.

Результаты. Строение кардиомиоцитов недоношенных и доношенных крыс на 180-е сутки постнатального периода принципиально схоже. Однако относительная площадь ядер кардиомиоцитов недоношенных крыс ниже (p=0,02), а цитоплазмы ― выше (p=0,02), чем у доношенных животных. Исключительно в цитоплазме недоношенных крыс наблюдаются перинуклеарное набухание цитоплазмы, истончение миофибрилл, а также признаки повреждения митохондрий, такие как деструкция митохондриальных мембран, концентрическая организация крист митохондрий, диссоциация кластеров митохондрий.

Заключение. Преждевременное рождение оказывает пролонгированное негативное влияние на ультраструктуру кардиомиоцитов. Наблюдаемые структурные изменения приводят к нарушению энергопродукции в кардиомиоцитах недоношенных крыс в отдалённом постнатальном периоде онтогенеза.

论证。早产是心血管系统疾病早期发展的危险因素。迄今为止，还无法根据临床研究结果了解早产青少年和成人心肌细胞的结构特征。因此，通过实验研究早产对出生后远期本体发育阶段心肌细胞超微结构的影响具有重要意义。

本研究旨在确定性早熟大鼠左心室心肌细胞的超微结构特征。

材料和方法。该研究在足月（n=4，妊娠22天）和早产（n=4，妊娠21天）雄性Wistar大鼠中进行。对怀孕大鼠施用米非司酮诱发早产。在出生后个体发育的第180天，早产和足月后代被排除在实验之外。利用早产大鼠和早衰大鼠的左心室切片对心肌细胞进行超微结构研究（透射电子显微镜）。细胞核、细胞质、肌纤维和线粒体的相对面积是在收缩心肌细胞纵切面的电子图上确定的。

结果。出生后第180天早产和足月大鼠心肌细胞的结构基本相似。但是，但早产大鼠心肌细胞核相对面积低于足月动物(p=0.02),而胞质的相对面积比早产动物高（p=0.02）。细胞质核周肿胀、肌纤维变细以及线粒体损伤的迹象，如线粒体膜破坏、线粒体嵴同心组织、线粒体簇解离等，只在早产大鼠的细胞质中观察到。

结论。早产对心肌细胞超微结构有长期的负面影响。观察到的结构变化导致早产大鼠的心肌细胞在出生后的远期能量生成受损。

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