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Peroxisomes (microbodies) in the myocardium of rodents and primates. A comparative Ultrastructural cytochemical study
Abstract:
The occurrence of peroxisomes (microbodies), their cytochemical characteristics and their ultrastructural relationship to the neighboring organelles were investigated in the ventricular myocardium of four rodent (rat, rabbit, gerbil, and guinea pig) and two primate (Macaca java and Tupaya) species. The hearts were fixed by vascular perfusion with glutaraldehyde and incubated in alkaline diaminobenzidine media for visualization of catalase. The electron-dense reaction product of catalase was found in the myocardium of all examined species and was localized in 0.2--0.5 mum oval particles, surrounded by a single limiting membrane and located usually at the junction of I and A bands. The peroxisomes in the hearts of gerbil and Macaca java were especially long and tortuous. A close spatial association was found between the myocardial peroxisomes and mitochondria, lipid droplets, and the membranes of sarcoplasmic reticulum, especially the so-called junctional sarcoplasmic reticulum. These observations demonstrate the consistent occurrence of peroxisomes in the heart of various mammalian species and suggest that peroxisomes have important metabolic and physiological functions in myocardium.
Insights
Peroxisomes, crucial organelles, are consistently found in the mammalian heart. These microbodies play vital roles in myocardial metabolism and physiology across various species.
Area of Science:
- Cardiovascular Biology
- Cell Biology
- Histology
Background:
- Peroxisomes (microbodies) are organelles with diverse metabolic functions.
- Their presence and role in the heart muscle (myocardium) are not fully understood.
- Investigating peroxisomes in mammalian hearts can reveal insights into cardiac physiology.
Purpose of the Study:
- To investigate the occurrence and ultrastructural characteristics of peroxisomes in the ventricular myocardium of various mammalian species.
- To determine the cytochemical features and spatial relationships of myocardial peroxisomes with other organelles.
- To elucidate the potential metabolic and physiological significance of peroxisomes in the heart.
Main Methods:
- Comparative ultrastructural and cytochemical analysis of myocardial tissue from six mammalian species (four rodents, two primates).
- Vascular perfusion fixation with glutaraldehyde.
- Diaminobenzidine (DAB) staining for catalase visualization to identify peroxisomes.
Main Results:
- Peroxisomes were consistently identified in the myocardium of all examined species.
- These organelles, characterized by catalase activity, were typically 0.2–0.5 µm in diameter and oval.
- Peroxisomes exhibited close spatial associations with mitochondria, lipid droplets, and sarcoplasmic reticulum, particularly junctional sarcoplasmic reticulum.
Conclusions:
- Peroxisomes are a consistent feature of mammalian ventricular myocardium.
- The observed ultrastructural relationships suggest active interactions between peroxisomes and other cellular components.
- These findings indicate that peroxisomes likely play significant metabolic and physiological roles in the heart muscle.