Related Experiment Videos
Connective tissue changes in early ischemia of porcine myocardium: an ultrastructural study
Abstract:
Scanning electron microscopy and transmission electron microscopy were used together with tannic acid and ruthenium-red staining to examine connective tissue damage caused by acute myocardial ischemia for 20, 40 and 120 min in pig hearts. The microsphere blood flow technique revealed that blood flow was approximately 0.02 ml/min/g in inner, middle and outer thirds of the ischemic zone. After 20 min of occlusion of the left anterior descending coronary artery, the collagen network and microfilaments became irregularly arranged. After 40 min of occlusion, ruthenium-red positive glycoprotein material around the collagen fibrils and elastin began to disappear. After 2 h occlusion, the collagen fibrils and microfilaments had separated from the basement membrane. Collagen fibrils, elastic fibers, and microfilaments were broken down and were found in decreased quantities. These results have revealed that the connective tissue remains intact during the first 20 min of coronary occlusion despite zero blood flow and mild cellular changes but does undergo prominent alterations after 40 min of occlusion.
Insights
Connective tissue in pig hearts remains intact during the initial 20 minutes of acute myocardial ischemia. However, significant damage to collagen and microfilaments occurs after 40 minutes of coronary occlusion.
Area of Science:
- Cardiovascular Biology
- Connective Tissue Research
- Ischemic Pathology
Background:
- Acute myocardial ischemia leads to significant cellular damage.
- The role of connective tissue alterations in ischemic heart disease requires further investigation.
- Understanding the temporal changes in cardiac connective tissue is crucial for developing therapeutic strategies.
Purpose of the Study:
- To investigate the ultrastructural changes in cardiac connective tissue following acute myocardial ischemia in a porcine model.
- To determine the timeline of connective tissue damage in response to coronary artery occlusion.
Main Methods:
- Utilized scanning electron microscopy (SEM) and transmission electron microscopy (TEM).
- Employed tannic acid and ruthenium-red staining for enhanced visualization of tissue components.
- Assessed myocardial blood flow using the microsphere technique.
- Examined pig hearts subjected to 20, 40, and 120 minutes of left anterior descending coronary artery occlusion.
Main Results:
- Blood flow in the ischemic zone reduced to approximately 0.02 ml/min/g.
- After 20 minutes of ischemia, collagen networks and microfilaments showed irregular arrangement.
- By 40 minutes, ruthenium-red positive glycoprotein material around collagen and elastin diminished.
- After 120 minutes, collagen fibrils and microfilaments detached from the basement membrane, with evidence of breakdown and reduced quantities of collagen fibrils, elastic fibers, and microfilaments.
Conclusions:
- Cardiac connective tissue integrity is maintained during the first 20 minutes of acute myocardial ischemia, despite absent blood flow.
- Prominent connective tissue alterations, including collagen and microfilament degradation, become evident after 40 minutes of coronary occlusion.
- These findings highlight a critical time window for intervention in acute myocardial ischemia, focusing on preserving connective tissue structure and function.