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Electron microscopic study of left ventricular cardiomyocyte mitochondriom in rats subjected to head-down tilt
T V Lipina1, M V Shornikova, Yu S Chentsov
1Department of Cell Biology and Histology, Biological Faculty, M. V. Lomonosov Moscow State University.
Abstract:
The mitochondriom of left-ventricular cardiomyocytes in rats subjected to head-down tilt was studied at the electron microscopic level. The ultrastructure of individual mitochondria was disturbed and the number of intermitochondrial contacts in the perinuclear zone increased after 30-day head-down tilt. These parameters did not return to normal over 30 days after 30-day tilt. Repeated 14-day head-down tilt led to a more pronounced increase in the number of intermitochondrial contacts, mitochondria with abnormal ultrastructure were still observed.
Insights
Head-down tilt in rats disrupts cardiomyocyte mitochondria, increasing abnormal structures and intermitochondrial contacts. These changes persist long-term, indicating significant cardiac cell damage from prolonged or repeated tilt exposure.
Area of Science:
- Cardiovascular Physiology
- Cell Biology
- Mitochondrial Research
Background:
- Head-down tilt simulates microgravity effects on the cardiovascular system.
- Cardiac mitochondria are crucial for cardiomyocyte energy production and function.
- Understanding cellular adaptations to simulated microgravity is vital for space exploration and terrestrial health.
Purpose of the Study:
- To investigate the impact of head-down tilt on the ultrastructure of cardiac mitochondria in rat left ventricles.
- To assess the reversibility of observed mitochondrial changes after cessation of head-down tilt.
- To evaluate the effects of repeated head-down tilt exposure on mitochondrial morphology and contacts.
Main Methods:
- Electron microscopy was used to examine the ultrastructure of mitochondria in left-ventricular cardiomyocytes.
- Rats were subjected to prolonged (30-day) and repeated (14-day) head-down tilt protocols.
- Mitochondrial morphology, intermitochondrial contacts, and perinuclear alterations were quantified.
Main Results:
- A 30-day head-down tilt induced mitochondrial ultrastructural disturbances and increased intermitochondrial contacts near the nucleus.
- These mitochondrial abnormalities persisted for 30 days after the tilt period, showing limited recovery.
- Repeated 14-day head-down tilt exposures resulted in a more significant increase in intermitochondrial contacts and persistent abnormal mitochondrial structures.
Conclusions:
- Head-down tilt significantly impairs cardiac mitochondrial ultrastructure and increases intermitochondrial contacts in a persistent manner.
- The observed mitochondrial damage suggests a potential mechanism for cardiac dysfunction under simulated microgravity conditions.
- Repeated or prolonged exposure exacerbates these detrimental effects on cardiomyocyte mitochondria, highlighting the need for countermeasures.
