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Updated: Dec 26, 2025
Preparation of Highly Coupled Rat Heart Mitochondria
Published on: September 23, 2010
Mitochondria in the Nuclei of Rat Myocardial Cells
Chupalav M Eldarov1, Irina M Vangely1, Valeriya B Vays1
1A.N. Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, 119991 Moscow, Russia.
Abstract:
Electron microscopic study of cardiomyocytes taken from healthy Wistar and OXYS rats and naked mole rats (Heterocephalus glaber) revealed mitochondria in nuclei that lacked part of the nuclear envelope. The direct interaction of mitochondria with nucleoplasm is shown. The statistical analysis of the occurrence of mitochondria in cardiomyocyte nuclei showed that the percentage of nuclei with mitochondria was roughly around 1%, and did not show age and species dependency. Confocal microscopy of normal rat cardiac myocytes revealed a branched mitochondrial network in the vicinity of nuclei with an organization different than that of interfibrillar mitochondria. This mitochondrial network was energetically functional because it carried the membrane potential that responded by oscillatory mode after photodynamic challenge. We suggest that the presence of functional mitochondria in the nucleus is not only a consequence of certain pathologies but rather represents a normal biological phenomenon involved in mitochondrial/nuclear interactions.
Insights
Mitochondria were found within the nuclei of cardiac cells in multiple species, suggesting a normal biological role in mitochondrial-nuclear interactions, not just pathology.
Area of Science:
- Cell Biology
- Mitochondrial Biology
- Cardiac Physiology
Background:
- Mitochondria are crucial for cellular energy production.
- Their presence within the nucleus is typically associated with pathological conditions.
- The normal biological role of intranuclear mitochondria remains largely unexplored.
Purpose of the Study:
- To investigate the presence and characteristics of mitochondria within cardiomyocyte nuclei.
- To determine if intranuclear mitochondria represent a normal biological phenomenon or a pathological artifact.
- To explore the functional implications of mitochondria in close proximity to the nucleus.
Main Methods:
- Electron microscopy was used to examine cardiomyocyte ultrastructure in Wistar rats, OXYS rats, and naked mole rats (Heterocephalus glaber).
- Confocal microscopy was employed to visualize mitochondrial networks near nuclei in rat cardiac myocytes.
- Mitochondrial membrane potential was assessed using photodynamic challenges to evaluate energetic functionality.
Main Results:
- Mitochondria were observed within cardiomyocyte nuclei lacking portions of the nuclear envelope, indicating direct nucleoplasm interaction.
- Approximately 1% of cardiomyocyte nuclei contained mitochondria, with no significant age or species dependency observed.
- A distinct, energetically functional branched mitochondrial network was identified near nuclei, differing from interfibrillar mitochondria.
Conclusions:
- The presence of functional mitochondria within cardiomyocyte nuclei appears to be a normal biological phenomenon.
- These intranuclear mitochondria may play a role in mitochondrial-nuclear interactions.
- This finding challenges the view of intranuclear mitochondria as solely indicative of pathology.
