Related Experiment Video
Updated: Aug 12, 2026
Myocardial Infarction and Functional Outcome Assessment in Pigs
Published on: April 25, 2014
Time course of endothelial dysfunction and myocardial injury during coronary arterial occlusion
G E Viehman1, X L Ma, D J Lefer
1Department of Physiology, Jefferson Medical College, Thomas Jefferson University, Philadelphia, Pennsylvania 19107.
Insights
Permanent myocardial ischemia impairs coronary endothelial function over time, with significant reductions in vasorelaxation after 4.5 hours. Myocardial damage and neutrophil accumulation were delayed, indicating endothelial dysfunction precedes significant tissue injury.
Area of Science:
- Cardiovascular Physiology
- Vascular Biology
- Ischemic Heart Disease Research
Background:
- Myocardial ischemia without reperfusion is a critical condition affecting heart muscle and blood vessels.
- Understanding the temporal effects on the coronary endothelium and myocardium is vital for developing therapeutic strategies.
Purpose of the Study:
- To investigate the time-dependent effects of permanent myocardial ischemia on coronary vascular endothelium and myocardium in a feline model.
- To assess the functional changes in vasodilation and structural integrity of the coronary arteries and heart muscle.
Main Methods:
- Anesthetized cats underwent occlusion of the left anterior descending (LAD) coronary artery for varying durations (1.5-6.0 hours).
- Coronary ring responsiveness to endothelium-dependent (acetylcholine, A23187) and independent (sodium nitrite) vasodilators was measured.
- Transmission electron microscopy and myeloperoxidase activity were used to evaluate endothelial and myocardial damage, and neutrophil infiltration.
Main Results:
- Endothelial-dependent vasorelaxation to acetylcholine significantly decreased after 4.5 hours of ischemia (33% of control) and remained low at 6.0 hours (31% of control).
- Endothelium-independent vasodilation was minimally affected, with only a moderate decrease in response to sodium nitrite after 6.0 hours.
- Minimal endothelial damage was observed via electron microscopy, while significant myocardial damage and neutrophil accumulation were delayed until after 4.5 hours of ischemia.
Conclusions:
- Coronary endothelial dysfunction, particularly impaired vasodilation, occurs relatively early during permanent myocardial ischemia.
- Significant myocardial damage and inflammatory cell infiltration follow the initial endothelial dysfunction.
- These findings highlight the progressive nature of ischemic injury and the critical role of endothelial function in its early stages.
Abstract:
The time course of the effects of permanent myocardial ischemia without reperfusion on the coronary vascular endothelium and myocardium were investigated in anesthetized cats. The left anterior descending (LAD) coronary artery was occluded for 1.5, 3.0, 4.5, or 6.0 h. Coronary rings from the ischemic LAD and the nonischemic left circumflex (LCX) arteries were tested for their responsiveness to the endothelium-dependent vasodilators acetylcholine (ACh, 0.1-100 nM) and the calcium ionophore A23187 (1-1,000 nM), and the endothelium-independent vasodilator sodium nitrite (NaNO2, 0.1-100 microM). Vasorelaxation was not significantly impaired in response to ACh after 1.5 h of ischemia and only moderately impaired after 3.0 h of ischemia (63 +/- 5% of control). However, after 4.5 h of ischemia the ACh-induced response was decreased to 33 +/- 4% of control and further declined to 31 +/- 4% of control after 6.0 h (P less than 0.001 from 1.5 h). There was no significant decrease in LCX ring vasorelaxant responses to vasodilators at all times, and the LAD rings only showed a moderately decreased response to NaNO2 after 6.0 h of ischemia (82 +/- 4% relaxation, P less than 0.05). Transmission electron microscopy revealed very little endothelial damage at 4.5 and 6.0 h, with only some subendothelial swelling noted. Damage to the myocardium did not become significant until after 4.5 h of ischemia, and cardiac myeloperoxidase activity, indicative of neutrophil accumulation, was not significant at any time.(ABSTRACT TRUNCATED AT 250 WORDS)
Related Concept Videos
01:20Blood Studies for Cardiovascular System I: Cardiac Biomarkers
The essential diagnostic tools for detecting myocardial necrosis and monitoring individuals suspected of having acute coronary syndrome (ACS) include:
Troponins
Troponins, particularly cardiac troponins I and T, are the most precise and sensitive markers of myocardial injury. They are detectable within 4-6 hours of myocardial injury and remain...
01:21Myocarditis I: Introduction
01:26Coronary Artery Disease II: Pathophysiology
01:30Acute Coronary Syndrome I: Introduction
01:19Acute Coronary Syndrome II: Pathophysiology and Clinical Manifestations
01:30Acute Coronary Syndrome III: Diagnostic Studies