Related Experiment Videos
Cellular morphometric changes in cat hearts subjected to three hours of regional ischaemia
1Department of Anatomy, University of Bergen, Norway.
Insights
Left anterior descending coronary artery occlusion in cats caused mitochondrial swelling and cytoplasmic edema in ischemic and border zones. Even normally perfused areas showed signs of damage, indicating widespread cardiac effects.
Area of Science:
- Cardiovascular Science
- Cardiac Pathophysiology
- Mitochondrial Biology
Background:
- Myocardial ischemia, resulting from left anterior descending coronary artery (LAD) occlusion, is a critical condition affecting heart muscle.
- Understanding the cellular and subcellular changes during ischemia is crucial for developing therapeutic strategies.
- Previous studies have focused on the ischemic zone, but effects on border and normally perfused regions require further investigation.
Purpose of the Study:
- To investigate the morphological changes in myocardial tissue, including mitochondria and cytoplasm, following LAD occlusion.
- To compare the effects of ischemia on the ischemic zone, border zone, and normally perfused myocardium.
- To assess the extent of cellular damage and edema in different myocardial regions.
Main Methods:
- Induction of LAD occlusion for three hours in anesthetized open-chest cats (n=7).
- Collection of myocardial biopsies from normal, border, and ischemic zones, identified by fluorescein staining and blood flow measurements.
- Sham-operated cats (n=7) served as controls.
- Quantitative morphometry using standard point counting techniques to determine fractional volumes of mitochondria, myofibrils, and cytoplasm, and to analyze mitochondrial outer membrane integrity.
Main Results:
- A distinct border zone showed greater mitochondrial swelling compared to the ischemic zone.
- The ischemic zone exhibited more pronounced cytoplasmic edema and a higher percentage of damaged cells than the border zone.
- The ischemic zone had the highest water content.
- Cytoplasmic edema was also observed in the normally perfused (normal) zone of LAD-occluded cats compared to controls, indicating systemic effects.
Conclusions:
- LAD occlusion leads to significant mitochondrial and cytoplasmic alterations in ischemic and border zones.
- The study highlights a gradient of damage, with the ischemic zone being most severely affected, followed by the border zone.
- Importantly, LAD occlusion impacts even normally perfused myocardial regions, suggesting a broader pathophysiological response beyond the immediate ischemic area.
Abstract:
The left anterior descending coronary artery (LAD) was occluded for three hours in seven anaesthetized open chest cats. Seven cats served as sham operated controls. Biopsies were collected from the mid-myocardium of the normal, border and ischaemic zones as defined by fluorescein staining and verified by blood flow measurements with radiolabelled microspheres. In the sham operated hearts the biopsies were taken from the mid-myocardium of the lateral wall of the left ventricle. Fractional volumes of mitochondria, myofibrils and remaining cytoplasm as well as data on the outer mitochondrial membrane were obtained by standard point counting techniques. In the LAD occluded hearts we observed a morphologically distinct lateral border zone characterized by a greater swelling of the mitochondria than in the ischaemic zone. However, in this group a more marked oedema of the cytoplasm and a greater percentage of heavily damaged cells were observed in the ischaemic than in the border zone. The ischaemic zone also had the largest water content. Furthermore, cytoplasmic oedema occurred in the normal zone of the LAD occluded cats when compared with the sham operated controls. This indicates that LAD occlusion also affects the normally perfused parts of the heart.